Updated on 2022/03/30

写真a

 
TAKEOKA, Yukikazu
 
Organization
Graduate School of Engineering Molecular and Macromolecular Chemistry 2 Associate professor
Graduate School
Graduate School of Engineering
Undergraduate School
School of Engineering Chemistry and Biotechnology
Title
Associate professor
Contact information
メールアドレス

Degree 1

  1. 工学博士 ( 上智大学 ) 

Research Areas 13

  1. Others / Others  / Softmaterials

  2. Others / Others  / Polymer/Textile Materials

  3. Others / Others  / Properties of Polymer

  4. Nanotechnology/Materials / Bio chemistry

  5. Nanotechnology/Materials / Fundamental physical chemistry

  6. Nanotechnology/Materials / Inorganic compounds and inorganic materials chemistry

  7. Nanotechnology/Materials / Inorganic/coordination chemistry

  8. Nanotechnology/Materials / Green sustainable chemistry and environmental chemistry

  9. Nanotechnology/Materials / Polymer chemistry

  10. Nanotechnology/Materials / Functional solid state chemistry

  11. Nanotechnology/Materials / Polymer materials

  12. Nanotechnology/Materials / Organic functional materials

  13. Nanotechnology/Materials / Energy chemistry

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Current Research Project and SDGs 1

  1. Functionalized Softmaterials

Research History 3

  1. Nagoya University   Graduate School of Engineering Molecular and Macromolecular Chemistry 2   Associate professor

    2017.4

  2. Research associate of Yokohama National University

    1998.7 - 2004.3

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    Country:Japan

  3. Research associate of Massachusetts Institute of Technology

    1996.4 - 1998.6

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    Country:Japan

Education 3

  1. Sophia University   Graduate School, Division of Humanities and Social Sciences

    - 1996

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    Country: Japan

  2. Sophia University   Graduate School, Division of Humanities and Social Sciences

    - 1996

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    Country: Japan

  3. Sophia University   Faculty of Science and Engineering   Department of Applied Chemistry

    - 1991

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    Country: Japan

Professional Memberships 3

  1. 日本化学会

  2. 高分子学会

  3. 日本化学会

Awards 12

  1. 市村学術賞功績賞

    2016   市村財団   白色と黒色の材料から作る様々な色の色材の開発

    竹岡敬和

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    Award type:Award from publisher, newspaper, foundation, etc.  Country:Japan

  2. 市村学術賞功績賞

    2016   市村財団   白色と黒色の材料から作る様々な色の色材の開発

    竹岡敬和

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    Award type:Honored in official journal of a scientific society, scientific journal  Country:Japan

  3. 高分子学会三菱化学賞

    2015.9   高分子学会  

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    Country:Japan

  4. 永井科学技術財団学術賞

    2014.3   永井科学技術財団  

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    Country:Japan

  5. 花王研究奨励賞

    2009.6   花王芸術財団  

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    Country:Japan

  6. 平成19年度 コニカミノルタ画像科学奨励賞

    2007   コニカミノルタ画像科学振興財団  

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    Country:Japan

  7. 第55回コロイドおよび界面化学討論会ポスター賞

    2002  

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    Country:Japan

  8. 財団法人「手島工業教育資金団」手島記念研究賞(手島工業技術研究賞)

    2001  

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    Country:Japan

  9. 日本MRS学会 2001年度奨励賞

    2001  

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    Country:Japan

  10. 日本MRS学会 2000年度奨励賞

    2000  

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    Country:Japan

  11. 上原生命科学記念財団ポストドクトラルフェロー

    1996  

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    Country:Japan

  12. The 1995 JORGE HELLER Journal of Controlled Release/CRS OUTSTANDING PAPER AWARD (1995)(1995年度JORGE HELLER Journal of Controlled Release

    1995  

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Papers 250

  1. Angle-Independent Structural Colored Materials

    TAKEOKA Yukikazu

    NIHON GAZO GAKKAISHI (Journal of the Imaging Society of Japan)   Vol. 60 ( 5 ) page: 520 - 527   2021.10

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:The Imaging Society of Japan  

    <p>From the perspective of biodiversity conservation, in the 21st century, environmentally friendly manufacturing is required to achieve the SDGs (sustainable development goals). Among the colored materials that make our lives colorful and rich, such as dyes and pigments, those that are harmful to human health and the environment need to be changed to safe materials. In nature, we are already using safe, low-fading structural colored materials that exhibit a variety of hues, without the use of toxic compounds and heavy metals. In this article, I would like to introduce bright angle-independent structural colored materials that use only safe and inexpensive white and black materials.</p>

    DOI: 10.11370/isj.60.520

    CiNii Research

  2. Functional polymethacrylate composite elastomer filled with multilayer graphene and silica particles

    Asai F., Seki T., Takeoka Y.

    Carbon Trends   Vol. 4   2021.7

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Carbon Trends  

    In this work, a three-component composite elastomer consisting of poly(di(ethylene glycol)methyl ether methacrylate) (PMEO2MA), 110 nm spherical silica particles and multilayer graphene (MLG) is fabricated and its various functions brought about by the characteristic morphology formed by silica particles and MLG are clarified. The presence of silica particles greatly improved the dispersibility of MLG in PMEO2MA, allowing more MLG to be filled. The relative dielectric constant (ε) of the composite elastomers can be increased by increasing the amount of MLG while suppressing the increase in dielectric loss tangent (tanδ). The thermal conductivity of the composite elastomer peak in the middle of the increase in MLGs when the silica particles are not filled, whereas the silica particle-filled system is able to fill the MLGs up to a higher volume fraction and shows higher thermal conductivity. The dynamic viscoelasticity analysis of the composite elastomers shows that the filling effect of MLG is more remarkable in the composite elastomer containing 40 vol% silica particles. The loss factor of vibration damping is found to be larger in the 40 vol% SiO2 - 2.8 vol% MLG composite elastomer over a wider frequency range than in the non-MLG samples.

    DOI: 10.1016/j.cartre.2021.100064

    Scopus

  3. Optical properties of photonic ball consisting of SiO<sub>2</sub> colloidal particles Ⅱ

    Ohnuki Ryosuke, Yoshioka Shinya, Takeoka Yukikazu, Sakai Miki

    Meeting Abstracts of the Physical Society of Japan   Vol. 74.1 ( 0 ) page: 3135 - 3135   2019

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:The Physical Society of Japan  

    DOI: 10.11316/jpsgaiyo.74.1.0_3135

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  4. Angular dependence of reflection in photonic balls

    Ryosuke Ohnuki, Shinya Yoshioka, Miki Sakai, Yukikazu Takeoka

    Meeting Abstracts of the Physical Society of Japan   Vol. 74.2 ( 0 ) page: 2767 - 2767   2019

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:The Physical Society of Japan  

    DOI: 10.11316/jpsgaiyo.74.2.0_2767

    CiNii Research

  5. Optical properties of photonic ball consisting of SiO<sub>2</sub> colloidal particles

    Ohnuki Ryosuke, Yoshioka Shinya, Takeoka Yukikazu, Sakai Miki, Seki T., Naoi Yui

    Meeting Abstracts of the Physical Society of Japan   Vol. 73.2 ( 0 ) page: 2558 - 2558   2018

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:The Physical Society of Japan  

    DOI: 10.11316/jpsgaiyo.73.2.0_2558

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  6. 角度依存性のない構造発色性材料

    竹岡 敬和

    科学と工業   Vol. 1   page: 246 - 251   2016

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    Language:English   Publishing type:Research paper (scientific journal)  

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  7. Fusion Materials for Biomimetic Structurally Colored Materials Reviewed

    竹岡 敬和

    Polymer Journal   Vol. 47   page: 106 - 113   2015

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  8. コロイド粒子集合体と光との相互作用

    竹岡 敬和

    化学と工業   Vol. 印刷中   2015

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    Language:English   Publishing type:Research paper (scientific journal)  

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  9. 高分子ゲルの靱性と伸張性の向上~架橋点が自由に動くポリロタキサン架橋剤を用いた柔軟性の高い刺激応答性高分子ゲルの構築とその物性

    竹岡 敬和

    MATERIAL STAGE   Vol. 15   page: 1 - 4   2015

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    Language:English   Publishing type:Research paper (scientific journal)  

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  10. 白い粒子と黒い粒子からカラフルな色をつくる

    竹岡 敬和

    塗装工学   Vol. 50   page: 76 - 83   2015

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    Language:English   Publishing type:Research paper (scientific journal)  

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  11. 白い粒子と黒い粒子からカラフルな色をつくる

    竹岡 敬和

    塗装工学   Vol. 50   page: 76 - 83   2015

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    Language:English   Publishing type:Research paper (scientific journal)  

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  12. コロイド粒子集合体と光との相互作用~角膜から学ぶ角度依存性の少ない構造発色性材料の構築~

    竹岡 敬和

    化学と工業   Vol. 68   page: 502 - 504   2015

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  13. Extremely stretchable thermosensitive hydrogels by introducing slide-ring polyrotaxane cross-linkers and ionic groups into the polymer network International journal

    Abu Bin Imran, Kenta Esaki, Hiroaki Gotoh, Takahiro Seki, Kohzo Ito, Yasuhiro Sakai, Yukikazu Takeoka

    NATURE COMMUNICATIONS   Vol. 5   page: 5124   2014.10

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:NATURE PUBLISHING GROUP  

    Stimuli-sensitive hydrogels changing their volumes and shapes in response to various stimulations have potential applications in multiple fields. However, these hydrogels have not yet been commercialized due to some problems that need to be overcome. One of the most significant problems is that conventional stimuli-sensitive hydrogels are usually brittle. Here we prepare extremely stretchable thermosensitive hydrogels with good toughness by using polyrotaxane derivatives composed of alpha-cyclodextrin and polyethylene glycol as cross-linkers and introducing ionic groups into the polymer network. The ionic groups help the polyrotaxane cross-linkers to become well extended in the polymer network. The resulting hydrogels are surprisingly stretchable and tough because the cross-linked alpha-cyclodextrin molecules can move along the polyethylene glycol chains. In addition, the polyrotaxane cross-linkers can be used with a variety of vinyl monomers; the mechanical properties of the wide variety of polymer gels can be improved by using these cross-linkers.

    DOI: 10.1038/ncomms6124

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  14. Production of Colourful Pigments Consisting of Amorphous Arrays of Silica Particles International journal

    Shinya Yoshioka, Yukikazu Takeoka

    CHEMPHYSCHEM   Vol. 15 ( 11 ) page: 2209 - 15   2014.8

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    It is desirable to produce colourful pigments that have anti-fading properties and are environmentally friendly. In this Concept, we describe recently developed pigments that exhibit such characteristics. The pigments consist of amorphous arrays of submicron silica particles, and they exhibit saturated and angle-independent structural colours. Variously coloured pigments can be produced by changing the size of the particles, and the saturation of the colour can be controlled by incorporating small amounts of black particles. We review a simple analysis that is useful for interpreting the angular independence of the structural colours and discuss the remaining tasks that must be accomplished for the realistic application of these pigments.

    DOI: 10.1002/cphc.201402095

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  15. 青い色を示す鳥の羽を模倣した角度依存性のない構造発色材料 Reviewed

    竹岡 敬和

    日本ゴム協会誌   Vol. 印刷中   2014

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  16. クリスチャンセンフィルター効果を利用した刺激に応じて色を変える相分離型発色材料

    竹岡 敬和

    「"自己組織化"がもたらす材料科学の新境地」機能材料   Vol. 33   page: 32 - 37   2013

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  17. クリスチャンセンフィルター効果を利用した刺激に応じて色を変える相分離型発色材料

    竹岡 敬和

    機能材料   Vol. 33   page: 32 - 37   2013

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  18. Structurally Coloured Secondary Particles Composed of Black and White Colloidal Particles International journal

    Yukikazu Takeoka, Shinya Yoshioka, Midori Teshima, Atsushi Takano, Mohammad Harun-Ur-Rashid, Takahiro Seki

    SCIENTIFIC REPORTS   Vol. 3   page: 2371   2013

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:NATURE PUBLISHING GROUP  

    This study investigated the colourful secondary particles formed by controlling the aggregation states of colloidal silica particles and the enhancement of the structural colouration of the secondary particles caused by adding black particles. We obtained glossy, partially structurally coloured secondary particles in the absence of NaCl, but matte, whitish secondary particles were obtained in the presence of NaCl. When a small amount of carbon black was incorporated into both types of secondary particles, the incoherent multiple scattering of light from the amorphous region was considerably reduced. However, the peak intensities in the reflection spectra, caused by Bragg reflection and by coherent single wavelength scattering, were only slightly decreased. Consequently, a brighter structural colour of these secondary particles was observed with the naked eye. Furthermore, when magnetite was added as a black particle, the coloured secondary particles could be moved and collected by applying an external magnetic field.

    DOI: 10.1038/srep02371

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  19. An amorphous array of poly(N-isopropylacrylamide) brush-coated silica particles for thermally tunable angle-independent photonic band gap materials International journal

    Yoshie Gotoh, Hiromasa Suzuki, Naomi Kumano, Takahiro Seki, Kiyofumi Katagiri, Yukikazu Takeoka

    NEW JOURNAL OF CHEMISTRY   Vol. 36 ( 11 ) page: 2171 - 2175   2012.11

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

    We precisely prepared thermo-responsive fine core-shell particles consisting of submicron sized silica particles as cores and high-density polymer brushes of thermo-responsive poly(N-isopropylacrylamide) (PNIPA) as shells. The shells were grown by atom transfer radical polymerisation from the initiator that was modified on the surface of the cores. These core-shell particles tend to aggregate in water, even at lower temperatures than the lower critical solution temperature of linear PNIPA. Nevertheless, along with PNIPA in water, changes in the particle size are dependent on water temperature. In accordance with these properties, the amorphous array of the core-shell particles exhibits temperature-reversible changes in the position and the strength of the photonic band gap that does not depend on angle.

    DOI: 10.1039/c2nj40368d

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  20. ゲル微粒子懸濁溶液が示す角度依存性のない構造色

    竹岡 敬和

    機能材料   Vol. 32   page: 25 - 28   2012

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  21. コロイドアモルファス集合体が示す角度依存性のない構造発色

    竹岡 敬和

    化学工業   Vol. 63   page: 57 - 61   2012

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  22. ゲル微粒子懸濁溶液が示す角度依存性のない構造色

    竹岡 敬和

    機能材料   Vol. 32   page: 25 - 28   2012

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  23. Tunable Angle-Independent Structural Color from a Phase-Separated Porous Gel International journal

    Naomi Kumano, Takahiro Seki, Masahiko Ishii, Hiroshi Nakamura, Yukikazu Takeoka

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 50 ( 17 ) page: 4012 - 5   2011.4

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-BLACKWELL  

    DOI: 10.1002/anie.201008182

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  24. Multicolor Polymer-Dispersed Liquid Crystals International journal

    Naomi Kumano, Takahiro Seki, Masahiko Ishii, Hiroshi Nakamura, Tomonari Umemura, Yukikazu Takeoka

    ADVANCED MATERIALS   Vol. 23 ( 7 ) page: 884 - +   2011.2

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:WILEY-BLACKWELL  

    The potential of a self-assembled phase-separated macroporous polymer film filled with an appropriate solvent for application in a functional multicolor polymer-dispersed liquid crystal (PDLC) display is explored. The findings demonstrate that a phase-separated porous MMAA-BIS polymer network filled with mixed LCs of 5CB and 5PCH can exhibit changes in structural color covering the whole visible region and an opaque milky color upon temperature variation. This system may be available for energy-saving multicolor displays.

    DOI: 10.1002/adma.201003660

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  25. Versatile Self-Assembled Hybrid Systems with Exotic Structures and Unique Functions Reviewed

    竹岡 敬和

    Current Opinion in Colloid & Interface Science   Vol. 16   page: 482 - 490   2011

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  26. Characteristics of disperse poly(N-isopropylacrylamide) brushes on silicon surfaces by Atom transfer radical polymerization Reviewed

    竹岡 敬和

    Transactions of the Materials Research Society Japan   Vol. 35   page: 845 - 848   2010

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  27. Recent advances in hydrogels in terms of fast stimuli responsiveness and superior mechanical performance Reviewed

    竹岡 敬和

    Polymer Journal   Vol. 42   page: 839 - 851   2010

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  28. Dual Tuning of the Photonic Band-Gap Structure in Soft Photonic Crystals International journal

    Masaki Honda, Takahiro Seki, Yukikazu Takeoka

    ADVANCED MATERIALS   Vol. 21 ( 18 ) page: 1801 - +   2009.5

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    A dually tunable photonic crystal composed of thermosensitive gel particles confined in a pH-sensitive inverse-opal gel is reported. The position of the photonic band-gap can be thermally regulated, while its intensity is dramatically changed by pH. Reversible, independent, and extensive switching of the position and intensity of the photonic band-gap could be achieved using independent external stimuli.

    DOI: 10.1002/adma.200801258

    Web of Science

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  29. Structural Colored Liquid Membrane without Angle Dependence International journal

    Yukikazu Takeoka, Masaki Honda, Takahiro Seki, Masahiko Ishii, Hiroshi Nakamura

    ACS APPLIED MATERIALS & INTERFACES   Vol. 1 ( 5 ) page: 982 - 6   2009.5

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    We have demonstrated for the first time that condensed gel particle suspensions in amorphous-like states display structural color with low angle dependence. This finding is in contrast to the common understanding that a periodic dielectric structure is fundamental to photonic band gap (PBG) production, and it validates the theory that a "tight bonding model" that is applicable to semiconductor systems can also be applied to photonic systems. More practically, this structural colored suspension represents a promising new material for the manufacture of reflective full-color displays with a wide viewing angle and nonfading color materials. This liquid system shows promise as a display material because electronic equipment used for display systems can easily be filled with the liquid in the same way that liquid crystals are currently used.

    DOI: 10.1021/am900074v

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  30. Electrochromism based on structural colour changes in a polyelectrolyte gel International journal

    Kazuhide Ueno, Junji Sakamoto, Yukikazu Takeoka, Masayoshi Watanabe

    JOURNAL OF MATERIALS CHEMISTRY   Vol. 19 ( 27 ) page: 4778 - 4783   2009

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

    Electrochromism based on structural colours was demonstrated by employing a simple system composed of a two-electrode cell, a salt-free organic solvent, and a nanostructured electroactive soft material. A polyelectrolyte gel, poly(HEMA-co-MAPTA-PF6), with an inverse-opal structure was prepared by using a polystyrene close-packed colloidal crystal as a template. The resulting gel swollen in binary organic solvents exhibited monochromatic structural colours. The structural colour of the gel was altered over the entire visible light region by changing the solvent polarity. Moreover, the structural colour could be tuned by applying a relatively low voltage, where the change in the lattice constant of the inverse-opal along the gel thickness direction, triggered by an electrodragging force on the polyelectrolyte gel under the electric field, was responsible for the colour change. The present system offers a novel concept for full-colour electrochromic materials, and the system can be tuned to exhibit the full range of colours by using single materials.

    DOI: 10.1039/b900261h

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  31. Fabrication of mechanically improved hydrogels using a movable cross-linker based on vinyl modified polyrotaxane International journal

    Abu Bin Imran, Takahiro Seki, Toshiyuki Kataoka, Masatoshi Kidowaki, Kohzo Ito, Yukikazu Takeoka

    CHEMICAL COMMUNICATIONS   ( 41 ) page: 5227 - 9   2008.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

    This manuscript describes the preparation of new slide-ring gels by using a polyrotaxane as a cross-linker.

    DOI: 10.1039/b810290b

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  32. Photoregulated Wormlike Motion of a Gel International journal

    Shu-ichi Shinohara, Takahiro Seki, Takamasa Sakai, Ryo Yoshida, Yukikazu Takeoka

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 47 ( 47 ) page: 9039 - 43   2008

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    DOI: 10.1002/anie.200803046

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  33. An electro- and thermochromic hydrogel as a full-color indicator International journal

    Kazuhide Ueno, Kazuki Matsubara, Masayoshi Watanabe, Yukikazu Takeoka

    ADVANCED MATERIALS   Vol. 19 ( 19 ) page: 2807 - +   2007.10

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    Electric-field-triggered "two-state switching" between two arbitrary structural colors (see figure) in the entire visible region at certain temperatures is shown by a stimuli-responsive chromic hydrogel. The external rapid tuning in the structural color of this hydrogel is successfully achieved by introducing a periodically ordered interconnecting porous structure.

    DOI: 10.1002/adma.200700159

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  34. ゲルの体積相転移

    竹岡 敬和

    高分子 56     page: 26 - 27   2007

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  35. デルの体積相転移

    竹岡 敬和

    高分子 56     page: 26 - 27   2007

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  36. Design of novel microactuator made of self-oscillating gel by assembling the microbeads and controlling their crosslinking structures

    Sakai T., Kinoshita M., Takeoka Y., Seki T., Yoshida R.

    Polymer Preprints, Japan   Vol. 55 ( 2 ) page: 4538 - 4539   2006.12

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Polymer Preprints, Japan  

    We have prepared the self-oscillating polymer and gels composed of poly(N-isopropylacrylamide) in which ruthenium tris(2,2'-bipyridine) (Ru(bpy)3), a catalyst for the Belousov-Zhabotinsky (BZ) reaction, is covalently bonded to the polymer chain. They change the conformation rhythmically and periodically without external stimuli in closed system. In order to investigate crosslinking effect of the polymers, phase transition behaviors of the linear polymer and the nano-gel beads were analyzed by measuring the transmittance and fluorescence intensity. Furthermore, by arraying the gel beads on the substrate surface, we designed the nano-conveyer which enables to transport substances added on the surface with the propagation of chemical waves induced by the BZ reaction. Artificial worm-like gel having gradient structure was also obtained by unidirectional photopolymerization.

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  37. Preparation and optical properties of ordered arrays of glucose-responsible submicrogel particles trapped in inverse opal polystyrene

    Honda M., Takeoka Y., Seki T., Kataoka K.

    Polymer Preprints, Japan   Vol. 55 ( 2 ) page: 4583 - 4584   2006.12

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Polymer Preprints, Japan  

    First, we obtained a closest-packing photonic crystal that acts as a photonic crystal composed of monodisperse silica particles 300 nm in diameter. A styrene monomer containing an initiator was infiltrated into the crystal and was polymerized so as to trap the crystalline structure. The composite film was soaked in HF solution to remove the silica particles completely. Then the resulting inverse opal polystyrene film with interconnecting porous structure could serve as a template to obtain glucose-responsible nanogel particles. We found that the intensity of Bragg diffraction is altered by the existence of glucose due to the swelling of the embedded nanogel particles. Such behavior was dependent on the glucose concentration.

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  38. Photomechanical effect of azobenzene liquid crystalline gel impregnated with low molecular weight liquid crystals

    Hayata Y., Nagano S., Takeoka Y., Seki T.

    Polymer Preprints, Japan   Vol. 55 ( 2 )   2006.12

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Polymer Preprints, Japan  

    Azobenzene liquid crystalline gels were prepared by photopolymerization in the Isotropic state. The LC gels with porous structure were prepared by the method to infiltrate a monomer mixture into the closest-packing silica colloid crystals at 100°C. The composite film was soaked in HF solution to remove the silica particles completely. Both porous liquid crystalline gels and non-porous gels were impregnated with 5 CB. We confirmed the photo-induced volume change for both LC gel systems. The effect of introduction of porous structure will be discussed.

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  39. Selective surface modification of PNIPA gel surface by imprinting method

    Ueda A., Takeoka Y., Seki T.

    Polymer Preprints, Japan   Vol. 55 ( 2 ) page: 4573 - 4574   2006.12

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Polymer Preprints, Japan  

    In recent years, the study of the surface properties of gels have become the focus of much interest due to their function similarity to living body and biocompatibility. We think that the establishment of the innovative approach to the method bring a creation of custom-made surface-functionalized gels. In this study, we obtained surface-functionalized gels by an approach to introduce sulfonic acid group to the surface of a gel by molecularly imprinting method (Scheme 1). To elucidate the presence of the sulfonic acid group on the surface of the gel, we attempted the adsorption test of amino-group modified fluorescence microbeads onto the surface of the gel. The microbeads equably adsorbed on the surface of the gel prepared by this method.

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  40. Design of functional surface by arraying self-oscillationg nano-gel beads

    Sakai T., Takeoka Y., Seki T., Yoshida R.

    Polymer Preprints, Japan   Vol. 55 ( 1 )   2006.10

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    We have prepared the self-oscillating polymer and gels composed of poly(N-isopropylacrylamide) in which ruthenium tris(2,2′-bipyridine) (Ru(bpy)s), a catalyst for the BelousovZhabotinsky (BZ) reaction, is covalently bonded to the polymer chain. The periodic conformational or swelling-deswelling changes of the polymer and nano-gel beads were measured as the optical transmittance changes of the solution. In order to investigate crosslinking effect of the polymers, phase transition behaviors of the linear polymer and the nano-gel beads were analyzed by measuring the transmittance and fluorescence intensity. Furthermore, by arraying the gel beads on the substrate surface, we designed the nano-conveyer which enables to transport substances added on the surface with the propagation of chemical waves induced by the BZ reaction.

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  41. Preparation of crosslinked azobenzene liquid crystalline polymer films and their direct evaluation by UV-Vis absorption spectrum

    Hayata Y., Nagano S., Takeoka Y., Seki T.

    Polymer Preprints, Japan   Vol. 55 ( 1 )   2006.10

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    Crosslinked side-chain liquid crystalline polymers films containing azobenzene moieties were prepared by photopolymerization in the liquid crystalline state. Due to the small amount of azobenzene moieties introduced, the liquid crystalline phase transition and photoisomerization behavior of this film could be directly evaluated by UV-Vis absorption spectrum.

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  42. Preparation and optical properties of ordered arrays of glucose-responsible nanogel particles trapped in inverse opal polystyrene

    Honda M., Takeoka Y., Seki T., Kataoka K.

    Polymer Preprints, Japan   Vol. 55 ( 1 )   2006.10

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    First, we obtained a closest-packing photonic crystal that acts as a photonic crystal composed of monodisperse silica particles 300 nm in diameter. A styrene monomer containing an initiator was infiltrated into the crystal and was polymerized so as to trap the crystalline structure, The composite film was soaked in HF solution to remove the silica particles completely. Then the resulting inverse opal polystyrene film with interconnecting porous structure could serve as a template to obtain glucose-responsible nanogel particles. We found that the intensity of Bragg diffraction is altered by the existence of glucose due to the swelling of the embedded nanogel particles. Such behavior was dependent on the glucose concentration.

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  43. Patterning of NIPA gel surface by surface imprinting method

    Ueda A., Takeoka Y., Seki T.

    Polymer Preprints, Japan   Vol. 55 ( 1 )   2006.10

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    We fabricated the patterning of sulfonic acid groups on the surface of NIPA gel by surface imprinting method as following procedures: 1) amino-terminated SAMs was formed onto a silicon substrate. 2) UV light was irradiated on an amino-terminated SAMs through a photomask. 3) a vinyl monomer having sulfonic acid group was electrostatically coupled with the amino group of the SAMs. 4) A gel is prepared on the vinyl monomer modified silicon substrate by free-radical polymerization. We attempted the adsorption test of amino-group modified fluorescence microbeads onto the surface of the gel (figure 2). These results indicate that the surface modified gel membrane with sulfonic acid can be fabricated from this surface molecularly imprinting method.

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  44. Swelling behavior of polyrotaxane gels exhibiting structural colors

    Murayama H., Nagano S., Ito K., Takeoka Y., Seki T.

    Polymer Preprints, Japan   Vol. 55 ( 1 )   2006.10

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    A new type of gel called topological gel having mobile cross-links can be obtained by using polyrotaxanes as gel components. In the present study, polyrotaxane gels with inverse opal structures were prepared by templating a colloidal crystal of silica. The preparative conditions such as selection of crosslinking reagent, temperature, solvent are investigated in detail. As the consequence, polyrotaxane gels showing a structural color were obtained. The reflection wavelength was exactly correlated with the degree of swelling.

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  45. ゲル微粒子集積体の構築とその光学的挙動

    竹岡 敬和

    ケミカルエンジニアリング (印刷中)     2006

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  46. コロイド結晶をテンプレートとした構造色ゲルの作製とセンサーデバイスへの応用

    竹岡 敬和

    ポリマーフロンティア21 (印刷中)     2006

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  47. Design of nano-oscillation using self-oscillating polymer and the analysis of cooperative effects

    Sakai T., Takeoka Y., Seki T., Yoshida R.

    Polymer Preprints, Japan   Vol. 54 ( 2 ) page: 4755 - 4756   2005.12

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Polymer Preprints, Japan  

    We have prepared the self-oscillating polymer and gels composed of poly(N-isopropylacrylamide) in which ruthenium tris(2,2′-bipyridine) (Ru(bpy) 3), a catalyst for the Belousov-Zhabotinsky (BZ) reaction, is covalently bonded to the polymer chain. The periodic conformational or swelling-deswelling changes of the polymer and nano-gel beads were measured as the optical transmittance changes of the solution. In order to investigate crosslinking effect of the polymers, phase transition behaviors of the linear polymer and the nano-gel beads were analyzed by measuring the transmittance and fluorescence intensity. Furthermore, by arraying the gel beads on the substrate surface, we designed the nano-conveyer which enables to transport substances added on the surface with the propagation of chemical waves induced by the BZ reaction.

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  48. Proposal of multicolor electrochromic polymer gels

    Ueno K., Matsubara K., Watanabe M., Takeoka Y.

    Polymer Preprints, Japan   Vol. 54 ( 2 ) page: 4709 - 4710   2005.12

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    Periodically ordered macroporous gels having ionized groups, which can exhibit a monochromatic structural color and undergo a drastic change in the color in response to external stimuli, were prepared by thermally induced radical copolymerization of N-isopropylacrylamide (NIPA) and methacrylic acid (MAAc) using a close-packed silica colloidal crystal as a template. The temperature and pH sensitive optical properties were investigated by reflection spectroscopy. Furthermore, we demonstrated that such pH sensitive optical properties could be manipulated by local pH change induced by water electrolysis. In other words, the electrochromism resulting from the change in structural color was successfully achieved. It was also explored that multicolor electrochromism of the porous gel could be actualized by temperature control of the solution together with the application of sufficient voltage. Moreover, the dynamic optical properties were investigated by the analysis of the diffraction peaks and the actual observation of the volume change behavior. The optical dynamics was critically influenced by the volume change anisotropy of the porous gels.

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  49. Photo-control of spatio-temporal oscillation in a gel system with light-sensitive Belousov-Zhabotinsky reaction

    Shinohara S., Nagano S., Takeoka Y., Seki T., Yoshida R.

    Polymer Preprints, Japan   Vol. 54 ( 1 )   2005.12

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    A gel that is prepared by the copolymerization of ruthenium complex as a light sensitive catalyst for the Belousov-Zhabotinsky (BZ) reaction and N-isopropylacrylamide has been known to convert spatio-temporal chemical oscillation into physical motion with the BZ-reaction. We are concerned about the control of the physical motion using the light sensitive BZ-reaction. The physical motion was observed with the change in the structural colors that depend on the swelling of the gel. For the alteration in the physical motion by light irradiation, the spectral changes with the structural colors and the images will be reported.

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  50. Electrically induced structural color change in periodically ordered porous gels having ionized groups

    Ueno K., Matsubara K., Takeoka Y., Watanabe M.

    Polymer Preprints, Japan   Vol. 54 ( 1 )   2005.12

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    Periodically ordered porous gels having immobilized ionic groups were prepared using a close-packed colloidal crystal as a template. The optical properties of the porous gels were dynamically measured by reflection spectroscopy, when dc voltage of 1.80 V was applied between the electrodes in an aqueous solution, onto one of which the porous gels were placed. In this study, the porous hydrogels composed of thermo- and pH-sensitive building blocks were used. The porous hydrogels could drastically convert their optical properties in response to the local pH change induced by water electrolysis due to the voltage application. Moreover, we could precisely control such optical properties with altering temperature of the solution concurrently with applying the voltage.

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  51. Structural colored gel

    Takeoka Y.

    Polymer Preprints, Japan   Vol. 54 ( 2 ) page: 4702 - 4704   2005.12

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    "Smart" porous gels with different optical behaviors were synthesized by quantitative adjustment of the cross-linker in pre-gel solutions. A periodically ordered interconnecting porous structure could be created in the gels by using a closest-packing silica colloidal crystal as a template. The interconnecting porosity provides fast response to changes in temperature through the reversible swelling and shrinking of the gels, while the periodically ordered mesoscopic structure endows the porous gels with structural color, which can be tuned by simply changing the amount of the cross-linker in the pre-gel solutions.

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  52. Synthesis of photo-responsive porous poly(NIPA) gel and evaluation of its optical properties

    Matsubara K., Watanabe M., Takeoka Y.

    Polymer Preprints, Japan   Vol. 54 ( 1 )   2005.12

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    A thermosensitive inverse-opal-type porous gel having pendant azobenzene groups, prepared by using a closest-packing SiO2 colloidal crystal as a template, can reversibly change its structural color in response to thermo- and photo-stimuli in water. With varying temperature, the peak values, λmax, of the reflection spectra for the porous gel continuously shifted until the gel network expansion reaches a new equilibrium state, because the gel underwent an isotropic volume change. In contrast, upon UV irradiation from the normal to the gel surface, a new λmax possessing a wavelength longer than that in the dark appeared at constant temperatures, accompanied by the photoinduced volume change of the gel. The change in the λmax could be reversed to the original state by exposure to Vis light through a different process of the variation in the λmax upon the UV irradiation. We concluded that the photo-responsive porous gel undergoes a photoinduced bistable volume change by photo-stimuli. This system enables to convert a two-state isomerization model of the azobenzene molecules into the two-state volume and/or lattice constant change of the porous gel having the azobenzene groups.

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  53. Surface modification of gel by molecularly imprinting method

    Ueda A., Takeoka Y., Seki T.

    Polymer Preprints, Japan   Vol. 54 ( 1 )   2005.12

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    We fabricated a surface modified gel membrane by a molecularly imprinting method as following procedures: 1) a number of amino-terminated SAMs were formed onto a glass substrate by CVD method. 2) a vinyl monomer having sulfonic acid group was electrostatically coupled with the amino group of the SAMs. 3) A gel is prepared on the vinyl monomer modified glass substrate by free-radical polymerization. We are planning on observing the surface state of the gel by a contact angle measurement, XPS and a fluorescent maicrobeads adsorption method.

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  54. 構造色を示すゲル〜鋳型を用いたゲルの機能化〜

    竹岡 敬和

    現代化学 412     page: 24 - 31   2005

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  55. 発色性ゲルから観測される色の制御

    竹岡 敬和

    化学工業 10     page: 53 - 57   2005

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  56. Structural Colored Gel

    TAKEOKA Yukikazu

      Vol. 54 ( 4 ) page: 258 - 263   2005

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  57. Simple and precision design of porous gel as a visible indicator for ionic species and concentration

    H Saito, Y Takeoka, M Watanabe

    CHEMICAL COMMUNICATIONS   ( 17 ) page: 2126 - 7   2003.9

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    Here we report the design and synthesis of a novel porous gel for an ionic visible indicator. The rapid-responsive porous gel which reveals color changes depending on a potassium ion concentration was prepared using a templating technique.

    DOI: 10.1039/b304306a

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  58. Production of intergeneric hybrid calli from C-3 and C-4 species of Amaranthaceae through protoplast fusion

    Mastuti R, Miyake H, Taniguchi T, Takeoka Y

    JAPANESE JOURNAL OF CROP SCIENCE   Vol. 66 ( 3 ) page: 456 - 465   1997.9

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  59. Ultrastructural studies on the fusion product between protoplasts of mung bean and adzuki bean

    Mikaye IH, Taniguchi T, Takeoka Y

    JAPANESE JOURNAL OF CROP SCIENCE   Vol. 65 ( 2 ) page: 330 - 339   1996.6

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  60. RELATIONSHIPS BETWEEN VASCULAR BUNDLES OF PANICLE NECK INTERNODE AND CHARACTERS OF HEAD UNDER DIFFERENT PLANTING DENSITIES AND NITROGEN FERTILIZERS APPLIED IN ORYZA-SATIVA L

    CUI HJ, JIN RZ, TAKEOKA Y

    JAPANESE JOURNAL OF CROP SCIENCE   Vol. 64 ( 2 ) page: 216 - 220   1995.6

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  61. Bioinspired Color Elastomers Combining Structural, Dye, and Background Colors

    Pei Shi, Eiji Miwa, Jialei He, Miki Sakai, Takahiro Seki, Yukikazu Takeoka

    ACS Applied Materials & Interfaces   Vol. 13 ( 46 ) page: 55591 - 55599   2021.11

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society ({ACS})  

    DOI: 10.1021/acsami.1c19471

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  62. Mechanical Properties of Homogeneous Polymer Networks Prepared by Star Polymer Synthesis Methods

    Yusuke Baba, Guohao Gao, Mitsuo Hara, Takahiro Seki, Kotaro Satoh, Masami Kamigaito, Taiki Hoshino, Kenji Urayama, Yukikazu Takeoka

    Macromolecules   Vol. 54 ( 22 ) page: 10468 - 10476   2021.11

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    DOI: 10.1021/acs.macromol.1c01680

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  63. Detailed Analysis of Peripheral Reflection from a Photonic Ball

    Ryosuke Ohnuki, Miki Sakai, Yukikazu Takeoka, Shinya Yoshioka

    Advanced Photonics Research     page: 2100131 - 2100131   2021.10

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Wiley  

    DOI: 10.1002/adpr.202100131

  64. Morphologically Diverse Micro- and Macrostructures Created via Solvent Evaporation-Induced Assembly of Fluorescent Spherical Particles in the Presence of Polyethylene Glycol Derivatives. International journal

    Mina Han, Ikue Abe, Kazunori Matsuura, Yukikazu Takeoka, Takahiro Seki

    Molecules (Basel, Switzerland)   Vol. 26 ( 14 )   2021.7

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    The creation of fluorescent micro- and macrostructures with the desired morphologies and sizes is of considerable importance due to their intrinsic functions and performance. However, it is still challenging to modulate the morphology of fluorescent organic materials and to obtain insight into the factors governing the morphological evolution. We present a facile bottom-up approach to constructing diverse micro- and macrostructures by connecting fluorescent spherical particles (SPs), which are generated via the spherical assembly of photoisomerizable azobenzene-based propeller-shaped chromophores, only with the help of commercially available polyethylene glycol (PEG) derivatives. Without any extra additives, solvent evaporation created a slow morphological evolution of the SPs from short linear chains (with a length of a few micrometers) to larger, interconnected networks and sheet structures (ranging from tens to >100 µm) at the air-liquid interface. Their morphologies and sizes were significantly dependent on the fraction and length of the PEG. Our experimental results suggest that noncovalent interactions (such as hydrophobic forces and hydrogen bonding) between the amphiphilic PEG chains and the relatively hydrophobic SPs were weak in aqueous solutions, but play a crucial role in creating the morphologically diverse micro- and macrostructures. Moreover, short-term irradiation with visible light caused fast morphological crumpling and fluorescence switching of the obtained structures.

    DOI: 10.3390/molecules26144294

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  65. Nonturbid Fast Temperature-Responsive Hydrogels with Homogeneous Three-Dimensional Networks by Two Types of Star Polymer Synthesis Methods

    DoWoo Kwon, Yuto Jochi, Yuumi Okaya, Takahiro Seki, Kotaro Satoh, Masami Kamigaito, Taiki Hoshino, Kenji Urayama, Yukikazu Takeoka

    Macromolecules   Vol. 54 ( 12 ) page: 5750 - 5764   2021.6

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    Temperature-responsive polymer gel can rapidly and reversibly switch its various physical properties and has been used in practical applications including reservoirs for drug delivery systems, cell sheet preparation base materials for regenerative medicine, and switching elements for microchannels. However, the sudden volume shrinkage in the gel with rapid temperature change may cause the formation of a skin layer and the macrophase separation phenomenon of the polymer network. Due to this phenomenon, it usually takes a very long time to reach a thermodynamically stable shrunken state of the gel. By adjusting the heterogeneity of the network structure of the conventional temperature-responsive polymer gel and the monomer arrangement of the polymer, the polymer gel may shrink faster without causing skin layer formation or macrophase separation phenomenon. In this study, almost ideal homogeneous temperature-responsive polymer gels could be synthesized by combining two types of synthetic methods for well-defined star-shaped polymers, i.e., the core-first method with a multifunctional initiator and linking method with a divinyl compound as the cross-linker, using a polymerization system with extremely high living fashion to afford polymer chains with narrow molecular weight distributions. As a result, the temperature-responsive polymer gels derived from N-isopropylacrylamide (NIPA) with almost uniform network structure were successfully prepared, in which the number of polymer chains bonded to the cross-linking points and the molecular weight between them are quite uniform. Due to the high living fashion of the polymerization used in this method, a temperature-responsive copolymer gel composed of NIPA and other hydrophilic monomers could also be synthesized. The polymer gel consisting of star-shaped block polymers of NIPA and dimethylacrylamide (DMA) responded much faster than that with an uncontrolled network structure and uncontrolled monomer sequence distribution, which shrank completely in less than 1/60 time as fast with optical transparency and without either skin layer formation or macrophase separation of the polymer network during shrinkage.

    DOI: 10.1021/acs.macromol.1c00446

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  66. Silica Nanoparticle Reinforced Composites as Transparent Elastomeric Damping Materials

    Fumio Asai, Takahiro Seki, Taiki Hoshino, Xiaobin Liang, Ken Nakajima, Yukikazu Takeoka

    ACS Applied Nano Materials   Vol. 4 ( 4 ) page: 4140 - 4152   2021.4

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    Inspired by the structure of the cornea, which is the transparent front part of the eye, we developed a transparent and tough silica composite elastomer consisting of poly[di(ethylene glycol)methyl ether methacrylate] (PMEO(2)MA) and 110 nm spherical silica particles without using an organic cross-linking agent. While filler composite elastomers, such as reinforced rubbers, have complex compositions containing multiple additives (dispersants, plasticizers, vulcanizing agents, etc.), the composition of our composite elastomer is very simple. With an increased amount of silica particles, the fracture energy of the composite elastomer (20.2 MJ m(-3)) was improved by 25 times compared to that of unfilled PMEO(2)MA (0.8 MJ m(-3)). Nanoscale mapping using atomic force microscopy elucidated the presence of an interface layer (IL) of approximately 15 nm thickness with a high elastic modulus near the silica particles in the composite elastomer. The fracture energy of the composite elastomer was found to be a maximum when the particle surface distance was approximately 30 nm. This particle surface distance meant that the ILs were just in contact with each other. The surface charge density and Hansen solubility parameter of the silica particles indicated the ionization of silanol groups and interactions caused by hydrogen bonding between polymer chains and the silica surface. The array of silica particles embedded with intervals of a few nanometers was expected to be able to effectively dissipate deformation energy as heat due to shear strain and friction between the particle surface and polymer matrices. Measurements of the vibration-damping properties revealed that the loss factor of the composite elastomer was significantly higher than that of the unfilled elastomer, indicating that the composite elastomer in this study could be applied as an interlayer film for laminated glass in automotive and architectural applications.

    DOI: 10.1021/acsanm.1c00472

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  67. Stimuli-Responsive Structural Colored Gel That Exhibits the Three Primary Colors of Light by Using Multiple Photonic Band Gaps Acquired from Photonic Balls

    Yumiko Ohtsuka, Miki Sakai, Takahiro Seki, Ryosuke Ohnuki, Shinya Yoshioka, Yukikazu Takeoka

    ACS Applied Materials & Interfaces   Vol. 12 ( 48 ) page: 54127 - 54137   2020.12

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    DOI: 10.1021/acsami.0c17687

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  68. Tough and 3D-Printable Poly(2-methoxyethyl Acrylate)-Silica Composite Elastomer with Anti-Platelet Adhesion Property. Reviewed International journal

    Fumio Asai, Takahiro Seki, Ayae Sugawara-Narutaki, Kazuhide Sato, Jérémy Odent, Olivier Coulembier, Jean-Marie Raquez, Yukikazu Takeoka

    ACS applied materials & interfaces   Vol. 12 ( 41 ) page: 46621 - 46628   2020.10

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    Poly(2-methoxyethyl acrylate) (PMEA) has attracted attention as a biocompatible polymer that is used as an antithrombotic coating agent for medical devices, such as during artificial heart and lung fabrication. However, PMEA is a viscous liquid polymer with low Tg, and its physical strength is poor even if a cross-linker is used, so it is difficult to make tough and freestanding objects from it. Here, we design and fabricate a biocompatible elastomer made of tough, self-supporting PMEA-silica composites. The toughness of the composite elastomer increases as a function of silica particle filling, and the stress at break of it is improved from 0.3 MPa to 6.7 MPa. The fracture energy of the composite elastomer with 39.5 vol% silica particles is up to 15 times higher than that of the cross-linked PMEA with no silica particles and the material demonstrates stress-strain behavior that is similar to that of biological soft tissue, which exhibits nonlinear elasticity. In addition, the composite elastomer shows the potential to be an antithrombotic property, while the results of the platelet adhesion test of the composite elastomer show that the number of adhered platelets is not significantly affected by the silica addition. Since the composite elastomer can be rapidly 3D-printed into complex geometries with high resolution features, it is expected to contribute to the development of medical devices from readily available materials.

    DOI: 10.1021/acsami.0c11416

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  69. Composite Elastomer Exhibiting a Stress-Dependent Color Change and High Toughness Prepared by Self-Assembly of Silica Particles in a Polymer Network Reviewed International journal

    Eiji Miwa, Kenta Watanabe, Fumio Asai, Takahiro Seki, Kenji Urayama, Jérémy Odent, Jean-Marie Raquez, Yukikazu Takeoka

    ACS Applied Polymer Materials   Vol. 2 ( 9 ) page: 4078 - 4089   2020.9

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    DOI: 10.1021/acsapm.0c00703

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  70. Robust Structurally Colored Coatings Composed of Colloidal Arrays Prepared by the Cathodic Electrophoretic Deposition Method with Metal Cation Additives Reviewed International journal

    Kiyofumi Katagiri, Kensuke Uemura, Ryo Uesugi, Naoki Tarutani, Kei Inumaru, Tetsuo Uchikoshi, Takahiro Seki, Yukikazu Takeoka

    ACS Applied Materials & Interfaces   Vol. 12 ( 36 ) page: 40768 - 40777   2020.9

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    Structurally colored coatings composed of colloidal arrays of monodisperse spherical particles have attracted great attention owing to their versatile advantages, such as low cost, resistance to fading, and low impacts on the environment and human health. However, the weak mechanical stability is considered to be a major obstacle for their practical applications as colorants. Although several approaches based on the addition of polymer additives to enhance the adhesion of particles have been reported, the challenge remains to develop a strategy for the preparation of structurally colored coatings with extremely high robustness using a simple process. Here, we have developed a novel approach to fabricate robust structurally colored coatings by cathodic electrophoretic deposition. The addition of a metal salt, i.e., Mg(NO3)(2), to the coating dispersion allows SiO2 particles to have a positive charge, which enables the electrophoresis of SiO2 particles toward the cathode. At the cathode, Mg(OH)(2) codeposits with SiO2 particles because OH- ions are generated by the decomposition of dissolved oxygen and NO3- ions. The mechanical stability of the colloidal arrays obtained by this process is remarkably improved because Mg(OH)(2) facilitates the adhesion of the particles and substrates. The brilliant structural color is maintained even after several cycles of the sandpaper abrasion test. We have also demonstrated the coating on a stainless steel fork. This demonstration reveals that our approach enables a homogeneous coating on a complicated surface. Furthermore, the high durability of the coating is clarified because the coating did not peel off even when the fork was stuck into a plastic eraser. Therefore, the coating technique developed here will provide an effective method for the pervasive application of the structural color as a colorant.

    DOI: 10.1021/acsami.0c10588

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  71. Monodisperse Silica Nanoparticle-Carbon Black Composite Microspheres as Photonic Pigments Reviewed International journal

    Miki Sakai, Hyunji Kim, Yusuke Arai, Takuya Teratani, Youhei Kawai, Yuichi Kuwahara, Keisuke Abe, Yasuhiro Kuwana, Katsuji Ikeda, Kazuhiko Yamada, Yukikazu Takeoka

    ACS APPLIED NANO MATERIALS   Vol. 3 ( 7 ) page: 7047 - 7056   2020.7

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    The development of nonbleachable colorants made of safe and inexpensive materials is a scientifically important task in view of future environmental and biological impacts. In this study, the conditions under which spherical colloidal crystals (photonic balls) formed mainly of sub-micron-sized monodispersed silica fine particles and carbon black exhibit vivid structural coloring were systematically investigated. The (111) plane of the face-centered cubic colloidal crystal formed by the silica particles is mainly oriented on the surface of the photonic balls formed from monodispersed silica particles. As a result, light in a specific wavelength region is reflected from the photonic balls according to the Bragg condition. When silica particles with diameters of 221, 249, and 291 nm are used, the peaks of the Bragg reflections generated from the photonic balls occur at 495, 562, and 647 nm, respectively; each photonic ball exhibits the ability to produce blue, green, and red colors. In particular, when a black background is used, a vivid structural color is observed from each photonic ball, and it is possible to reproduce all colors using the three primary colors of light by changing the mixture ratio of these photonic balls. The introduction of a small amount of carbon black into the photonic balls makes it possible to reproduce the additive color mixture by the three primary colors of light even when the background color is white. We report that safe and nonbleachable coloring materials with controlled nanosized periodic structures and micrometer-sized geometric structures can be developed using three types of photonic balls consisting of safe and inexpensive silica fine particles with/without carbon black.

    DOI: 10.1021/acsanm.0c01366

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  72. Optical Characterization of the Photonic Ball as a Structurally Colored Pigment Reviewed International journal

    Ryosuke Ohnuki, Miki Sakai, Yukikazu Takeoka, Shinya Yoshioka

    LANGMUIR   Vol. 36 ( 20 ) page: 5579 - 5587   2020.5

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    A photonic ball is a spherical colloidal crystal. Because it can exhibit vivid structural colors, many attempts have been made to apply it as a structurally colored pigment. However, the optical properties of the photonic ball are complicated because different crystal planes can be involved in the coloration mechanism, depending on the size of the constituent colloidal particles. In this paper, we report a comparative study of photonic balls consisting of silica particles with sizes ranging from 220 to 500 nm. We first analyze the reflectance spectra acquired in a nearly backscattering geometry and confirm that Bragg diffraction from different crystal planes causes several spectral peaks. Second, the angular dependence of reflection is experimentally characterized and theoretically analyzed with appropriate models. These analyses and a comparison with a planar colloidal crystal reveal that the spherical shape plays an essential role in the minor iridescence of photonic balls. We finally discuss a method to enhance color saturation by incorporating small light-absorbing particles. We also discuss the iridescence of the photonic ball under directional and ambient illumination conditions.

    DOI: 10.1021/acs.langmuir.0c00736

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  73. Highly Transparent and Tough Filler Composite Elastomer Inspired by the Cornea Reviewed International journal

    Kenta Watanabe, Eiji Miwa, Fumio Asai, Takahiro Seki, Kenji Urayama, Tomotaka Nakatani, So Fujinami, Taiki Hoshino, Masaki Takata, Chang Liu, Koichi Mayumi, Kohzo Ito, Yukikazu Takeoka

    ACS MATERIALS LETTERS   Vol. 2 ( 4 ) page: 325 - 330   2020.4

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    We propose a strategy to develop a colorless, transparent, and tough composite elastomer inspired by the cornea, which is the transparent front portion of the eyeball. The composite elastomer, in which 34 vol % hard silica particles with a uniform particle size are dispersed as a filler in a low-crosslinking polymer network exhibits a fracture energy that is similar to 13.5 times higher than that of a system without the silica particles. This strategy also makes the elastomer optically transparent, because the light scattered by each silica particle that forms an ordered structure in the polymer network is cancelled by interference. This research may pave the way for the development of optically transparent and durable materials for applications such as advanced medical devices and soft robots.

    DOI: 10.1021/acsmaterialslett.9b00520

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  74. Improvement of mechanical properties of elastic materials by chemical methods International journal

    Yukikazu Takeoka, Sizhe Liu, Fumio Asai

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   Vol. 21 ( 1 ) page: 817 - 833   2020.2

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    Elastomers such as gels and rubbers play various roles in our lives. Elastomers, which guarantee the safety of airplanes and automobiles and the stability of buildings, are materials that have made the lives of people in the twentieth century extremely convenient. The existence of macromolecules, that is, giant molecules, has been clarified; the development of synthetic macromolecules has progressed; and understanding of elastomers has progressed. By introducing new ideas, it has become possible to obtain tough and hard elastomers, which was difficult under conventional ideas. In this paper, we will explain the development from the classical theory of elastomers to current efforts.

    DOI: 10.1080/14686996.2020.1849931

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  75. Precise Synthesis of a Homogeneous Thermoresponsive Polymer Network Composed of Four-Branched Star Polymers with a Narrow Molecular Weight Distribution Reviewed International journal

    Yuumi Okaya, Yuto Jochi, Takahiro Seki, Kotaro Satoh, Masami Kamigaito, Taiki Hoshino, Tomotaka Nakatani, So Fujinami, Masaki Takata, Yukikazu Takeoka

    Macromolecules   Vol. 53 ( 1 ) page: 374 - 386   2020.1

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    In this study, the synthesis of a star-shaped polymer with a narrow molecular weight distribution and subsequent formation of a homogeneous polymer network composed of the star-shaped polymer were realized by combining single-electron transfer living radical polymerization, click reaction, and amide bond formation with a condensing agent, which are toolized reactions. First, a 4-armed star polymer consisting of N-isopropylacrylamide was synthesized by living radical polymerization using N,N'-ethylenebis (2,2-dichloroacetamide) as a 4-branched initiator. By this polymerization method, a terminal Cl 4-branched star poly(N-isopropylacrylamide) (PNIPA) with a narrow molecular weight distribution could be obtained, but it was found that the reaction activity of the polymer terminal was lost in the process of purification and isolation. Therefore, after obtaining the terminal Cl 4-branched star PNIPA by living radical polymerization, an azide reaction was carried out in one pot without purification and isolation of the star-shaped polymer. As a result, the azide group was successfully introduced to all ends of the star-shaped polymer. By introducing a carboxyl group or an amino group into the 4-branched star polymer with azide groups using a click reaction, two types of 4-branched star polymers with different end groups were obtained. Equal amounts of both 4-branched star polymers were mixed at a polymer concentration equal to or higher than the overlapping concentration, and as a result of forming an amide bond with a condensing agent, a polymer gel was obtained. The swelling behaviors of the polymer gel indicate that almost no unreacted carboxyl group or amino group was present in the obtained polymer gel. That is, it was found that both 4-branched star polymers reacted efficiently to form a polymer network. In addition, structural observation of the polymer network by the small-angle X-ray scattering method showed that a polymer gel consisting of a network of uniform size was obtained. As mentioned above, we succeeded in constructing a polymer gel consisting of a homogeneous network structure using a temperature responsive 4-branched star polymer as the building block. The living radical polymerization method, the click reaction, and the amide formation by condensation reaction used in this study can be applied not only to the NIPA used here but also to various other monomers. If the construction of a precise network structure is realized by many polymers and the relation with the functional expression derived from the structure is clarified, it will be possible to design the network structure in accordance with the usage of the polymer gel.

    DOI: 10.1021/acs.macromol.9b01616

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  76. Characterization of Colloidal Amorphous Arrays Prepared by Uniaxial Pressure Application Reviewed International journal

    Yui Naoi, Takahiro Seki, Ryosuke Ohnuki, Shinya Yoshioka, Yukikazu Takeoka

    LANGMUIR   Vol. 35 ( 43 ) page: 13983 - 13990   2019.10

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    We prepared a colloidal amorphous array by applying uniaxial pressure to a powder of monodispersed colloidal silica particles. Pellet-shaped samples were obtained that exhibit different structural colors depending on the diameter of the particles. We characterized the optical properties of the arrays by measuring the angle-dependent scattering spectrum wherein several spectral peaks were observed. The peak at the longest wavelength was caused by the short-range order of the particle arrangement. Interestingly, this peak exhibited a smaller shift in wavelength than that observed in similar samples prepared by several different methods. The other spectral peaks were thought to originate from Mie scattering, which produces a color when the diameter of the colloidal particles is appropriately chosen. Our results showed that uniaxial pressure application can be a suitable method to prepare structurally colored pigments with low angle dependence.

    DOI: 10.1021/acs.langmuir.9b02622

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  77. Colorful Photonic Pigments Prepared by Using Safe Black and White Materials Reviewed International journal

    Miki Sakai, Takahiro Seki, Yukikazu Takeoka

    ACS SUSTAINABLE CHEMISTRY & ENGINEERING   Vol. 7 ( 17 ) page: 14933 - 14940   2019.9

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    The methods used to prepare vivid color materials that have supported our rich lifestyle are due for review, with the goal of using chemical substances that minimize the significant adverse effects on human health and the environment. In this research, we found that pigments of various colors can be obtained by utilizing submicron-sized amorphous silica fine particles and a complex of iron and tannic acid (Fe-TA complex), which are used for foods, cosmetics, etc. Silica fine particles with uniform submicron particle size appear as a white powder. When silica fine particles form spherical colloidal crystals with short-range order, long-distance order, and periodicity or form colloidal amorphous arrays with only short-range order, the fine particle arrays strongly scatter light with a specific wavelength in all directions. If the wavelength is in the visible light region, these arrays can be used as color materials displaying colors with low angle dependence. However, such arrays formed only from silica fine particles can appear whitish when observed with the naked eye because of noncoherent multiple scattering of light from the interior. Introducing a black Fe-TA complex inside the arrays reduces the effect of the noncoherent multiple scattering of light, and the arrays exhibit bright colors. Safe and inexpensive pigments exhibiting various hues and saturations can be obtained by controlling the size of the silica fine particles, the form of the fine particle arrays, and the incorporated state of the Fe-TA complex. By including TA, the mechanical stability of fine particle arrays and their adhesion to glass substrates are improved, and therefore, the fine particle arrays can be used as coating films.

    DOI: 10.1021/acssuschemeng.9b03165

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  78. Development of angle-independent color material using colloidal amorphous array Reviewed International journal

    Yui Naoi, Takahiro Seki, Shinya Yoshioka, Yukikazu Takeoka

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   Vol. 688 ( 1 ) page: 105 - 113   2019.7

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    Color materials utilizing physical phenomena such as scattering, diffraction, and interference of light have drawn attention as alternatives to organic dyes that fade by light and some inorganic pigments that are highly toxic. For example, a color material exhibiting structural color caused by a fine structure with a size that is on the order of the wavelength can be prepared using only human body or environmentally friendly materials. If the fine structure is kept stable, the structural colored material can be a nonfading color material. We know that a conventional structural colored material exhibits a property that the hue greatly changes depending on the light irradiation direction and the viewing direction. Recent studies have shown that colloidal amorphous arrays obtained with spherical colloidal particle aggregates with short-range order have almost no angle dependence of the hue under natural light where light is irradiated from all directions. However, the structural color generated from the colloidal amorphous array exhibits angle dependence on the hue under the condition that light is irradiated only from one direction. In this study, we found a light scattering peak, in the scattering spectrum observed from the colloidal amorphous array, showing no angle dependence at all on the shorter wavelength side than the light scattering peak caused by the existence of the short-range order. By exploiting this scattering phenomenon, we will explain the possibility of producing a color material with no angle dependence on the hue even under the condition that light is irradiated only from one direction.

    DOI: 10.1080/15421406.2019.1651075

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  79. Grating Diffraction or Bragg Diffraction? Coloration Mechanisms of the Photonic Ball Reviewed International journal

    Ryosuke Ohnuki, Shinji Isoda, Miki Sakai, Yukikazu Takeoka, Shinya Yoshioka

    ADVANCED OPTICAL MATERIALS   Vol. 7 ( 13 )   2019.7

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    The coloration mechanism of the photonic ball is investigated, which is a spherical aggregation of submicrometer-sized colloidal particles. An interesting optical property is reported for photonic balls with colloidal particles larger than 400 nm: a ring-like iridescent reflection appears on the peripheral part of the ball when observed under an optical microscope. Previous studies considered grating diffraction or Bragg diffraction separately to explain this iridescence. Here, it is shown from detailed structural and optical investigations that both diffraction mechanisms are important. In particular, Bragg diffraction explains the presence of a specific color for the photonic ball when observed with the naked eye in contrast to the iridescence seen under the microscope. The essential idea of the optical analysis is to combine the Bragg diffraction that occurs in the 3D periodic structure with the grating diffraction that originates from the surface with a 2D periodicity. The macroscopic color is almost independent of the angle of observation because of this unique reflection mechanism; hence, the photonic ball can be a suitable candidate for the structurally colored pigment.

    DOI: 10.1002/adom.201900227

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  80. Optically transparent, high-toughness elastomer using a polyrotaxane cross-linker as a molecular pulley Reviewed

    Hiroaki Gotoh, Chang Liu, Abu Bin Imran, Mitsuo Hara, Takahiro Seki, Koichi Mayumi, Kohzo Ito, Yukikazu Takeoka

    SCIENCE ADVANCES   Vol. 4 ( 10 ) page: eaat7629   2018.10

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    An elastomer is a three-dimensional network with a cross-linked polymer chain that undergoes large deformation with a small external force and returns to its original state when the external force is removed. Because of this hyperelasticity, elastomers are regarded as one of the best candidates for the matrix material of soft robots. However, the comprehensive performance required of matrix materials is a special challenge because improvement of some matrix properties often causes the deterioration of others. For example, an improvement in toughness can be realized by adding a large amount of filler to an elastomer, but to the impairment of optical transparency. Therefore, to produce an elastomer exhibiting optimum properties suitable for the desired purpose, very elaborate, complicated materials are often devised. Here, we have succeeded in creating an optically transparent, easily fabricated elastomer with good extensibility and high toughness by using a polyrotaxane (PR) composed of cyclic molecules and a linear polymer as a cross-linking agent. In general, elastomers having conventional cross-linked structures are susceptible to breakage as a result of loss of extensibility at high cross-linking density. We found that the toughness of the transparent elastomer prepared using the PR cross-linking agent is enhanced along with its Young's modulus as cross-linking density is increased.

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  81. Spontaneous synthesis of a homogeneous thermoresponsive polymer network composed of polymers with a narrow molecular weight distribution

    Jochi Yuto, Seki Takahiro, Soejima Takamasa, Satoh Kotaro, Kamigaito Masami, Takeoka Yukikazu

    NPG ASIA MATERIALS   Vol. 10   page: 840-848   2018.8

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    DOI: 10.1038/s41427-018-0074-x

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  82. Bioinspired Color Materials Combining Structural, Dye, and Background Colors

    Sakai Miki, Seki Takahiro, Takeoka Yukikazu

    SMALL   Vol. 14 ( 30 )   2018.7

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    DOI: 10.1002/smll.201800817

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  83. Spontaneous Preparation of Monodispersed, Structural Colored, Spherical Particles by Rotational Stirring

    Teshima Midori, Suzuki Motoki, Seki Takahiro, Takeoka Yukikazu

    CHEMNANOMAT   Vol. 4 ( 7 ) page: 621-625   2018.7

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    DOI: 10.1002/cnma.201800102

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  84. Environment and human friendly colored materials prepared using black and white components

    Takeoka Yukikazu

    CHEMICAL COMMUNICATIONS   Vol. 54 ( 39 ) page: 4905-4914   2018.5

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    DOI: 10.1039/c8cc01894d

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  85. Structural Coloration of a Colloidal Amorphous Array is Intensified by Carbon Nanolayers

    Takeoka Yukikazu, Iwata Masanori, Seki Takahiro, Nueangnoraj Khanin, Nishihara Hirotomo, Yoshioka Shinya

    LANGMUIR   Vol. 34 ( 14 ) page: 4282-4288   2018.4

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    DOI: 10.1021/acs.langmuir.8b00242

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  86. Angle-independent structural colored materials by black and white components

    Takeoka Yukikazu

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   Vol. 255   page: .   2018.3

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  87. Preparation of angle-independent color materials by applying Mie resonances

    Naoi Yui, Takeoka Yukikazu, Seki Takahiro

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   Vol. 255   page: .   2018.3

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  88. Simple preparation of magnetic field-responsive structural colored Janus particles

    Teshima Midori, Seki Takahiro, Takeoka Yukikazu

    CHEMICAL COMMUNICATIONS   Vol. 54 ( 21 ) page: 2607-2610   2018.3

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    DOI: 10.1039/c7cc09464g

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  89. Angle-independent structural colored materials by black and white components Reviewed

    Yukikazu Takeoka

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   Vol. 255   page: .   2018.3

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  90. Preparation of angle-independent color materials by applying Mie resonances Reviewed

    Yui Naoi, Yukikazu Takeoka, Takahiro Seki

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   Vol. 255   page: .   2018.3

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  91. Structurally colored coating films with tunable iridescence fabricated via cathodic electrophoretic deposition of silica particles Reviewed

    Kiyofumi Katagiri, Kensuke Uemura, Ryo Uesugi, Kei Inumaru, Takahiro Seki, Yukikazu Takeoka

    RSC ADVANCES   Vol. 8 ( 20 ) page: 10776 - 10784   2018

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    In recent years, colloidal arrays of submicrometer-sized monodisperse particles used as structurally colored coatings have drawn great attention due to their non-bleaching properties and low impact on human health and the environment. In this paper, structurally colored coating films were fabricated using monodisperse SiO2 particles via the cathodic electrophoretic deposition (EPD) technique. The addition of a strong polycation, poly(diallyldimethylammonium chloride) (PDDA), enables the cathodic EPD of SiO2 particles and carbon black (CB) additives. Optimizing the quantities of PDDA and CB results in the appearance of vivid structural color from the coating films. The arrangement of the particle array is controllable by varying the pH of the water added to the coating sols for EPD. Structurally colored coating films with and without iridescence, i.e., angular dependence, can be fabricated on demand by a simple operation of the EPD process. In addition, the coating film prepared by cathodic EPD displayed high abrasion resistance because PDDA acts not only as a charge control agent but also as a binder.

    DOI: 10.1039/c8ra01215f

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  92. Angle-independent colored materials based on the Christiansen effect using phase-separated polymer membranes

    Takeoka Yukikazu

    POLYMER JOURNAL   Vol. 49 ( 3 ) page: 301-308   2017.3

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    DOI: 10.1038/pj.2016.117

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  93. Highly Responsive Hydrogel out of Poly(N-isopropyl acryalamide) Grafted Polyrotaxane as Building Block Designed by Living Radical polymerization and Click Chemistry Reviewed

    Yasumoto, A., Gotoh, H., Gotoh, Y., Imran, A. B., Seki, T., Sakai, Y., Ito, K., Takeoka, Y.

    Macromolecules   Vol. 50   page: 364-374   2017

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    DOI: 10.1021/acs.macromol.6b01955

  94. Structural color coating films composed of an amorphous array of colloidal particles via electrophoretic deposition Reviewed

    Katagiri, K.,* Tanaka, Y., Uemura K., Inumaru, K., Seki, T., Takeoka, Y.

    NPG Asia Materials   Vol. 9   page: e355   2017

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    DOI: 10.1038/am.2017.13

  95. Bio-inspired Bright Structurally Coloured Colored Colloidal Amorphous Array Enhanced by Controlling Thickness and Black Background Reviewed

    Ogawa, K., Hara, M., Nagano, S., Seki, T., Takeoka, Y.

    Advanced Materials   Vol. 29   page: 1605050(1-8)   2017

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    DOI: 10.1002/adma.201605050

  96. Photo-tunable Christiansen Colour Filter Using Photoisomerization of Stilbene Reviewed

    Ogawa, K., Hara, M., Nagano, S., Seki, T., Takeoka, Y.

    Chem. Lett.   Vol. 46   page: 1386-1389   2017

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    DOI: 10.1246/cl.170603

  97. Various Structural Colored Pigments Prepared by White and Black Fine Particles

    TAKEOKA Yukikazu

    Journal of the Japan Society of Colour Material   Vol. 90 ( 11 ) page: 393-397 - 397   2017

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    &lt;p&gt;Because safety to the environment and people is respected, safe and inexpensive non-fading colored materials are required. In this review, I will explain how to prepare a material displaying a vivid structural color by using a fine structure that is a comparable to the wavelength size of visible light and a black substance.&lt;/p&gt;

    DOI: 10.4011/shikizai.90.393

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  98. 白と黒の材料から作られるカラフルな色材:—鮮やかな構造色の発現には,微細構造と黒色物質の存在が重要—

    竹岡 敬和

    化学と教育   Vol. 65 ( 12 ) page: 640-643 - 643   2017

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    &lt;p&gt;自然界には,大きく分けて二種類の発色方法がある。染料や顔料を用いた発色と,光の波長サイズの微細構造を利用した発色である。人類は,多くの染料や顔料を自然界から集め,それを人工的に作る方法を身につけてきた。そのおかげで,現在の我々の生活は様々な色にあふれた豊かな環境にある。しかし,21世紀になってからは,人間や環境に対して,より負荷の低い安全な素材を用いた,高耐久性,高機能性を有する色材が求められるようになり,微細構造を利用した発色材料,つまり,構造発色性材料が注目されている。本稿では,自然にある構造発色性材料を取り上げ,これまでにあまり理解されていなかった構造発色性について説明する。&lt;/p&gt;

    DOI: 10.20665/kakyoshi.65.12_640

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  99. Molecular Weight Dependency of Polyrotaxane-cross-linked Polymer Gel Extensibility Reviewed

    Ohmori, K., Imran, A. B., Seki, T., Liu, C., Mayumi, K., Ito, K., Takeoka, Y.

    Chemical Communications   Vol. 52   page: 13757-13759   2016

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  100. Preparation of Structural Coloring Material using Functional Black Substance

    TAKEOKA Yukikazu

    Hosokawa Powder Technology Foundation ANNUAL REPORT   Vol. 24 ( 0 ) page: 66-69 - 69   2016

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    &lt;p&gt;Generally, we have an image that the structural colored material changes its hue depending on the direction of light irradiation and the viewing direction. I found that structural colored materials of various hues without angle dependence could be prepared from white and black materials. As a material, silica, titanium oxide, magnetite, and polymers can be used. We can obtain non-toxic and non-fading color materials at low cost using our materials, because the structural colored materials are composed of environment and people-friendly inexpensive materials. Moreover, because black materials exhibiting various functions such as conductivity, magnetic properties, photo-responsiveness, etc., functional colored materials utilizing these functions may be obtained.&lt;/p&gt;

    DOI: 10.14356/hptf.14110

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  101. Stimulus-responsive colored materials for sensing and display devices

    Yukikazu Takeoka

    Springer Series in Materials Science   Vol. 229   page: 33 - 50   2016

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    In this chapter, two types of angle-independent colored systems are described that are achieved without using dyes and pigments: one is a colloidal amorphous array composed of fine colloidal particles, and the other is a phase-separated colored material based on the Christiansen effect. Stimuli-responsive systems using these materials are also introduced.

    DOI: 10.1007/978-3-319-24990-2_2

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  102. Molecular weight dependency of polyrotaxane-cross-linked polymer gel extensibility Reviewed

    Kana Ohmori, Imran Abu Bin, Takahiro Seki, Chang Liu, Koichi Mayumi, Kohzo Ito, Yukikazu Takeoka

    CHEMICAL COMMUNICATIONS   Vol. 52 ( 95 ) page: 13757 - 13759   2016

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    This work investigates the influence of the molecular weight of polyrotaxane (PR) cross-linkers on the extensibility of polymer gels. The polymer gels, which were prepared using PR cross-linkers of three different molecular weights but the same number of cross-linking points per unit volume of gel, have almost the same Young's modulus. By contrast, the extensibility and rupture strength of the polymer gels are substantially increased with increasing molecular weight of the PR cross-linker.

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  103. Thermally Tunable Hydrogels Displaying Angle-Independent Structural Colors Reviewed

    Yumiko Ohtsuka, Takahiro Seki, Yukikazu Takeoka

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 54 ( 51 ) page: 15368 - 15373   2015.12

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    We report the preparation of thermally tunable hydrogels displaying angle-independent structural colors. The porous structures were formed with short-range order using colloidal amorphous array templates and a small amount of carbon black (CB). The resultant porous hydrogels prepared using colloidal amorphous arrays without CB appeared white, whereas the hydrogels with CB revealed bright structural colors. The brightly colored hydrogels rapidly changed hues in a reversible manner, and the hues varied widely depending on the water temperature. Moreover, the structural colors were angle-independent under diffusive lighting because of the isotropic nanostructure generated from the colloidal amorphous arrays.

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  104. Thermally Tunable Angle-independent Structurally Coloured Hydrogels Reviewed

    Ohtsuka, Y., Seki, T., Takeoka, Y

    Angew. Chem. Int. Ed.     page: in press   2015.12

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  105. Thermally Tunable Angle-independent Structurally Coloured Hydrogels Reviewed

    Ohtsuka, Y, Seki, T, Takeoka, Y

    Angew. Chem. Int. Ed.     page: in press   2015.12

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  106. Making colors from black and white

    Takeoka Yukikazu

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   Vol. 250   page: .   2015.8

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  107. Making colors from black and white Reviewed

    Yukikazu Takeoka

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   Vol. 250   page: .   2015.8

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  108. Fusion materials for biomimetic structurally colored materials Reviewed

    Yukikazu Takeoka

    POLYMER JOURNAL   Vol. 47 ( 2 ) page: 106 - 113   2015.2

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    This review addresses recent developments in structurally colored materials composed of submicrometer-sized fine particles, where the structural color is not angle-dependent. Recently, studies on colloidal crystals of submicrometer-sized fine particles for structurally colored materials applications have drawn great attention. Materials researchers have become aware that many living things exhibit bright structural colors that arise from amorphous arrays of particles, pores and fibers, and are now engaged in research related to this phenomenon. In particular, colloidal amorphous arrays composed of submicrometer-sized fine particles, which can display vivid structural color without angle dependence, have become a popular topic of study within recent years. In this paper, I review the possibility of using colloidal amorphous arrays as stimuli-responsive colored materials based on the properties of colloidal amorphous arrays that have been elucidated in recent experimental investigations.

    DOI: 10.1038/pj.2014.125

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  109. Fusion Materials for Biomimetic Structurally Colored Materials Invited Reviewed

    Y. Takeoka

    Polymer Journal   Vol. 47   page: 106-113   2015

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  110. Preparation of Structurally Colored, Monodisperse Spherical Assemblies Composed of Black and White Colloidal Particles using a Micro Flow-Focusing Device Reviewed

    Midori Teshima, Takahiro Seki, Ryuji Kawano, Shoji Takeuchi, Shinya Yoshioka, Yukikazu Takeoka

    J. Materials Chemistry C,   Vol. 3   page: 769-777   2015

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  111. Facile morphological control of fluorescent nano/microstructures via self-assembly and phase separation of trigonal azobenzenes showing aggregation-induced emission enhancement in polymer matrices Reviewed

    Han, M., Takeoka, Y., Seki, T.

    J. Materials Chemistry C,   Vol. 3   page: 4093-4098   2015

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    DOI: 10.1039/C5TC00462D

  112. Facile morphological control of fluorescent nano/microstructures via self-assembly and phase separation of trigonal azobenzenes showing aggregation-induced emission enhancement in polymer matrices

    Han Mina, Takeoka Yukikazu, Seki Takahiro

    JOURNAL OF MATERIALS CHEMISTRY C   Vol. 3 ( 16 ) page: 4093-4098   2015

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    DOI: 10.1039/c5tc00462d

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  113. Preparation of structurally colored, monodisperse spherical assemblies composed of black and white colloidal particles using a micro-flow-focusing device Reviewed

    Midori Teshima, Takahiro Seki, Ryuji Kawano, Shoji Takeuchi, Shinya Yoshioka, Yukikazu Takeoka

    JOURNAL OF MATERIALS CHEMISTRY C   Vol. 3 ( 4 ) page: 769 - 777   2015

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    It is very annoying when colors fade over time from exposure to bright light. A structurally colored material is a strong candidate for the fabrication of non-fading colored materials composed of environmentally friendly and non-toxic chemicals. We demonstrate that by using a micro-flow-focusing device, monodisperse spherical assemblies displaying various structural colors in air can be prepared from a suspension containing environmentally friendly white and black colloidal particles: monodisperse submicron-sized SiO2 colloidal particles and black magnetite colloidal particles. The average size of the monodisperse spherical assemblies can be controlled by changing the amount of SiO2 colloidal particles used in the preparation of the suspension. The hue of the monodisperse spherical assemblies can be varied by simply altering the size of the SiO2 colloidal particles. These monodisperse spherical assemblies exhibit either iridescent or non-iridescent structural colors, depending on the aggregation state of the SiO2 colloidal particles, which can be controlled by the presence or absence of an electrolyte. Moreover, the saturation of the colors produced by the monodisperse spherical assemblies can be altered by modifying the amount of magnetite colloidal particles that is added. Our results should offer new possibilities for structurally colored materials for future application in pigments and test agents.

    DOI: 10.1039/c4tc01929f

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  114. Colorful-pigment production with amorphous arrays of silica particles Invited Reviewed

    S. Yoshioka, Y. Takeoka

    ChemPhysChem     2014.6

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    DOI: doi.org/10.1002/cphc.201402095

  115. Light-induced Saturation Change in the Angle-independent Structural Coloration of Colloidal Amorphous Arrays Reviewed

    Hirashima, R., Seki, T., Katagiri, K., Akuzawa, Y., Torimoto, T., Takeoka, Y.

    J. Materials Chemistry C,   Vol. 2   page: 344-348   2014.1

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  116. Extremely stretchable thermosensitive hydrogels prepared by introducing polyrotaxane-based slide-ring cross-linkers and ionic groups into the polymer network Reviewed

    Abu Bin Imran, Kenta Esaki, Hiroaki Gotoh, Takahiro Seki, Kohzo Ito, Yasuhiro Sakai, Yukikazu Takeoka

    Nature Communications   Vol. 5   page: 5124:1-8   2014

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  117. Angle-independent Structural Coloured Materials inspired by Blue Feather Barbs

    TAKEOKA Yukikazu

    NIPPON GOMU KYOKAISHI   Vol. 87 ( 6 ) page: 226-230 - 230   2014

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    In this review, I introduce the microstructures and optical properties of angle-independent structurally coloured barbs of blue birds, then describe the fabrication and the optical nature of the artificially prepared imitations of such biological systems.

    DOI: 10.2324/gomu.87.226

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  118. Light-induced saturation change in the angle-independent structural coloration of colloidal amorphous arrays Reviewed

    Ryoko Hirashima, Takahiro Seki, Kiyofumi Katagiri, Yuki Akuzawa, Tsukasa Torimotoa, Yukikazu Takeoka

    JOURNAL OF MATERIALS CHEMISTRY C   Vol. 2 ( 2 ) page: 344 - 348   2014

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    Light-induced saturation changes in the angle-independent structural coloration of a colloidal amorphous array mainly composed of submicron-sized fine spherical silica particles including a tiny amount of titanium oxide nanoparticles were investigated using a photoelectrochemical reaction of the Ag/Ag+ system, which can exhibit a change in the brightness of the black color.

    DOI: 10.1039/c3tc31438c

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  119. Production of Colored Pigments with Amorphous Arrays of Black and White Colloidal Particles Reviewed

    Yukikazu Takeoka, Shinya Yoshioka, Atsushi Takano, Shigeo Arai, Khanin Nueangnoraj, Hirotomo Nishihara, Midori Teshima, Yumiko Ohtsuka, Takahiro Seki

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 52 ( 28 ) page: 7261 - 7265   2013.7

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    Sprayed: Pigments with various angle-independent colors were prepared by a spray method (see picture), which is a remarkably simple method using submicrometer-sized silica particles and carbon black. The use of a polyelectrolyte that adheres to the particles can stabilize the structure of the colloidal amorphous arrays to create highly stressable, nonfading pigments. Copyright © 2013 WILEY-VCH Verlag GmbH &amp
    Co. KGaA, Weinheim.

    DOI: 10.1002/anie.201301321

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  120. 角度依存性のない構造発色材料 (有機エレクトロニクス)

    竹岡 敬和

    電子情報通信学会技術研究報告 : 信学技報   Vol. 112 ( 410 ) page: 1-5   2013.1

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  121. 角度依存性のない構造発色材料

    竹岡 敬和

    電気学会研究会資料. DEI, 誘電・絶縁材料研究会   Vol. 2013 ( 1 ) page: 1-5   2013.1

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  122. Stimuli-Responsive Opals: Colloidal Crystals and Colloidal Amorphous Arrays for Use in Functional Structurally Colored Materials Invited Reviewed

    Takeoka, Y.

    J. Materials Chemistry C,   Vol. 1   page: 6059-6074   2013.1

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  123. Producing Coloured Pigments with Amorphous Arrays of Black and White Colloidal Particles Reviewed

    Takeoka, Y., Yoshioka, S., Takano, A., Arai, S., Khanin, N., Nishihara, H., Teshima, M., Ohtsuka, Y., Seki, T.

    Angew. Chem. Int. Ed.   Vol. 52   page: 7261-7265   2013.1

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  124. Structurally Coloured Secondary Particles Composed of Black and White Colloidal Particles Reviewed

    Takeoka, Y., Yoshioka, S., Teshima, M., Takano, A., Harun-Ur-Rashid, M., Seki, T.

    Sci. Rep.   Vol. 3   page: 2371-1-7   2013.1

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  125. Producing Coloured Pigments with Amorphous Arrays of Black and White Colloidal Particles Reviewed

    Takeoka, Y, Yoshioka, S, Takano, A, Arai, S, Khanin, N, Nishihara, H, Teshima, M, Ohtsuka, Y, Seki, T

    Angew. Chem. Int. Ed.   Vol. 52   page: 7261-7265   2013.1

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  126. Applications of Stimuli-Sensitive Inverse Opal Gels

    Takeoka Yukikazu

    RESPONSIVE PHOTONIC NANOSTRUCTURES: SMART NANOSCALE OPTICAL MATERIALS   ( 5 ) page: 150 - 189   2013

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    DOI: 10.1039/9781849737760-00150

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  127. Stimuli-responsive opals: colloidal crystals and colloidal amorphous arrays for use in functional structurally colored materials Reviewed

    Yukikazu Takeoka

    JOURNAL OF MATERIALS CHEMISTRY C   Vol. 1 ( 38 ) page: 6059 - 6074   2013

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    Two distinct types of colloidal particle aggregated states exist in opal, namely, the colloidal crystal and the colloidal amorphous array. Today, these aggregates can be artificially prepared and are now studied as non-fading structurally colored materials as a result of our better understanding of their optical properties. Additionally, by applying the aggregates as stimuli-responsive materials, we can fabricate stimuli-responsive structurally colored systems that change their hue and saturation in response to external stimuli. In this review, the conditions necessary for fabricating stimuli-responsive structurally colored systems using the two types of aggregates present in opal are explained.

    DOI: 10.1039/c3tc30885e

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  128. Angle-independent structural coloured amorphous arrays Reviewed

    Yukikazu Takeoka

    JOURNAL OF MATERIALS CHEMISTRY   Vol. 22 ( 44 ) page: 23299 - 23309   2012.11

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    We are able to observe a colour due to the interference of light from microstructures composed of different refractive index materials that is comparable to the visible wavelength of light; such a colour is called a structural colour. Because structural colour is fadeless and no energy is lost from the colour mechanism, structurally coloured materials are expected to be used for energy-saving reflective displays and sensors. Previously, however, the word "iridescence" rather than "structural colour" was used to describe the property of a surface that appears to change colour as the viewing angle or the angle of light illumination changes. Thus, people who are aware of the concept of interference colour have a strong impression that all structurally coloured materials change hue when viewed from different angles, as indicated by the term "iridescence." In fact, most artificial structurally coloured materials that we and other groups have studied so far change their hue depending on the viewing and light illumination angles because these structural colours are derived from Bragg reflection. Such angle dependence presents a barrier for developing displays and sensors using structurally coloured materials. Therefore, my group has been working to develop angle-independent structural coloured materials. The latest most notable ones are amorphous array systems. In this review, I first introduce the microstructures and optical properties of low-angle-dependent structurally coloured amorphous arrays in biological systems, then describe the fabrication and the optical nature of the artificially prepared imitations of such biological systems, and finally, present the related theoretical studies.

    DOI: 10.1039/c2jm33643j

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  129. Photoinduced Volume Transition in Liquid Crystalline Polymer Gels Swollen by a Nematic Solvent Reviewed

    Yuki Hayata, Shusaku Nagano, Yukikazu Takeoka, Takahiro Seki

    ACS MACRO LETTERS   Vol. 1 ( 11 ) page: 1357 - 1361   2012.11

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    Nematic liquid crystalline (LC) cross-linked polymer gel sheets containing 3 mol % azobenzene (Az) unit were prepared and swollen by a nematic solvent of 4'-pentyl-4-cyanobiphenyl (5CB). This 5CB-swollen gel sheet exhibited a discontinuous volume change around the nematic-isotoropic phase transition temperature of the LC gel (T-NI(G)). UV irradiation at a temperature slightly lower than T-NI(G) provoked a large volume transition (expansion) due to a loss of nematic order within the gel sheet caused by the trans-to-cis photoisomerization of Az. The volume was reverted by irradiation with 436 run light By templating the colloidal crystal film of monodispersed silica particles, a LC gel sheet possessing a microporous structure was also prepared. Due to the facilitated diffusion of 5CB the microporous LC gel exhibited significant enhancements,in the extent and rate of the photoinduced volume transition.

    DOI: 10.1021/mz300447j

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  130. Angle-independent Structural Coloured Amorphous Arrays

    Y. Takeoka

    J. Materials Chemistry   Vol. 22   page: 23299-23309   2012.4

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  131. Angle-independent Structural Coloured Amorphous Arrays

    Y. Takeoka

    J. Materials Chemistry   Vol. 22   page: 23299-23309   2012.4

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  132. Fabrication of mono-dispersed spherical assemblies and these structural colors by using microflow device International journal

    Midori Teshima, Yukikazu Takeoka, Takahiro Seki, Ryuji Kawano, Shinya Yoshioka, Shoji Takeuchi

    Proceedings of the 16th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2012     page: 644 - 646   2012.1

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    Structural colors are caused by the interaction of visible light with micro structures of the substances, on a length scale comparable to optical wavelength. We pay marked attention to the structural colored materials because of these less fading and low environment burden compared with the colored materials using dyes. This report shows that we fabricated monodispersed spherical assembly (MDSA) composed of submicron silica particles as a structural color material by using a micro flow focusing device (MFFD). Moreover, we will introduce the improvement for the coloration of the spherical assembly by magnetic particles.

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  133. Amorphous Array of Poly(N-isopropylacrylamide) Brush-Coated Silica Particles for Thermally Tunable Angle-Independent Photonic Band Gap Materials

    Gotoh, Y., Suzuki, H., Kumano, N., Seki, T., Katagiri, K., Takeoka, Y.

    New Journal of Chemistry   Vol. 36   page: 2171-2175   2012

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  134. Versatile self-assembled hybrid systems with exotic structures and unique functions Reviewed

    Takashi Nakanishi, Masanobu Naito, Yukikazu Takeoka, Kazunori Matsuura

    CURRENT OPINION IN COLLOID & INTERFACE SCIENCE   Vol. 16 ( 6 ) page: 482 - 490   2011.12

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    In this review article, we describe recent progress about exotic self-assembled systems with various dimensions including biomolecules, supramolecules, unique hydrophobic amphiphiles. polymers, nano-clusters. and colloidal particles. Construction of robust biomolecular assemblies with exotic structures, such as ring and hollow capsule, is achieved by rational designs of symmetric biomolecular conjugates. In addition, we comprehensively summarized leading-edge topics on optical/topological properties of self-assembled hybrid systems, such as circularly polarized luminescence or structural color. The preparation of colloidal amorphous array with photonic band gap-induced angle-independent structural color is also achieved in consideration of the following situations: i) two-body sphere-sphere potential, ii) disorder packing using different sizes of colloidal particles, and iii) softness of colloidal particles. Lastly, we demonstrated useful utilizations of exotic self-assembled objects. Flakelike microparticles were transcribed into various nano-flake metals and applied as temperature indicator for the local heating of an addictive. All findings described here show meaningful hybrid strategies in self-assembly techniques and their functionalization as well as materialization. (C) 2011 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.cocis.2011.08.003

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  135. Tunable Angle-Independent Structural Colour from Phase Separated Porous Gel Reviewed

    Kumano, N., Seki, T., Ishii, M., Nakamura, H., Takeoka, Y.

      Vol. 50   page: 4012-4015   2011

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  136. Versatile Self-Assembled Hybrid Systems with Exotic Structures and Unique Functions Invited Reviewed

    Nakanishi, T., Naito, M., Takeoka, Y., Matsuura, K.

    Current Opinion in Colloid and Interface Science   Vol. 16   page: 482-490   2011

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  137. Multi-Colour Polymer Dispersed Liquid Crystal Reviewed

    Kumano, N., Seki, T., Ishii, M., Nakamura, H., Umemura, T., Takeoka, Y.

    Adv. Mater.   Vol. 23   page: 884-888   2011

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  138. Precise Synthesis and Physicochemical Properties of High-Density Polymer Brushes designed with Poly(N-isopropylacrylamide) Reviewed

    Hiromasa Suzuki, Huda Muhammad Nurul, Takahiro Seki, Taisuke Kawamoto, Hisashi Haga, Kazushige Kawabata, Yukikazu Takeoka

    MACROMOLECULES   Vol. 43 ( 23 ) page: 9945 - 9956   2010.12

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    A high-density polymer brush of poly(N-isopropylacrylamide) (PNIPA) was precisely prepared following carefully selected procedures, which included selecting the underlying substrate, preparing its surface, and grafting PNIPA on the substrate. As a result, the graft density and the dried thickness of the brush reached more than 0.5 chains/nm(2) and 200 nm, respectively, for the best combination of each procedure. This high-density polymer brush showed gradual collapse with increasing temperature in water, which must be attributed to both the low swelling and the low shrinking abilities of the brush that result from the physically constrained state of the polymers. The contact angle of the air bubbles underneath the high-density polymer brush also gradually decreased up to around 25 degrees C in water with increasing temperature, which indicates that the hydrophilicity of the surface decreases as it does in typical PNIPA-grafted membranes and gels. Starting at the lower critical solution temperature of free PNIPA in water, approximately 32 degrees C, the value of the contact angle started to increase dramatically, and it became constant when the solution temperature exceeded 40 degrees C. Ultimately, the surface exhibited a mostly hydrophilic nature at higher temperatures. The temperature-dependent contact angles can be interpreted by assuming that the terminally chlorinated alkyl groups of the elongated PNIPAs can be positioned on the surfaces or hidden in the vicinity of the membranes, depending on the temperature of the solution.

    DOI: 10.1021/ma101439f

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  139. Recent advances in hydrogels in terms of fast stimuli responsiveness and superior mechanical performance

    Imran Abu Bin, Seki Takahiro, Takeoka Yukikazu

    Polymer journal   Vol. 42 ( 11 ) page: 839-851   2010.11

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  140. Recent advances in hydrogels in terms of fast stimuli responsiveness and superior mechanical performance

    Bin Imran Abu, Seki Takahiro, Takeoka Yukikazu

    POLYMER JOURNAL   Vol. 42 ( 11 ) page: 839-851   2010.11

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    DOI: 10.1038/pj.2010.87

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  141. Poly(N-isopropylacrylamide) Gel Prepared Using a Hydrophilic Polyrotaxane-Based Movable Cross-Linker Reviewed

    Abu Bin Imran, Takahiro Seki, Kohzo Ito, Yukikazu Takeoka

    MACROMOLECULES   Vol. 43 ( 4 ) page: 1975 - 1980   2010.2

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    A novel type of thermosensitive polymer gel was fabricated using a hydrophilic polyrotaxane as a movable cross-linker and N-isopropylacrylamide (NIPA) as a monomer. An optical transparence, mechanical softness, abnormal swelling capacity, and unprecedentedly fast thermosensitivity are among the salient features of this new polyNIPA gel in comparison with typical polyNIPA gels prepared by bifunctional cross-linker Such as N,N'-methylenebisacrylamide (TN gels) and a previously reported polyNIPA gel using a hydrophobic polyrotaxane as a cross-linker. Whereas TN gels can take more than a day to undergo full deswelling in response to sudden temperature change, Our new gel collapses in similar to 10 min. The hydrophilicity and movability of the cross-linker contribute to these unprecedented properties of this thermosensitive polyNIPA gel. Moreover, this new type of cross-linker can be applied to any of the conventional gels made by radical polymerization and will likely improve the stimuli responses and mechanical properties of the gels.

    DOI: 10.1021/ma902349j

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  142. Angle-Independent Structural Color in Colloidal Amorphous Arrays Reviewed

    Mohammad Harun-Ur-Rashid, Abu Bin Imran, Takahiro Seki, Masahiko Ishi, Hiroshi Nakamura, Yukikazu Takeoka

    CHEMPHYSCHEM   Vol. 11 ( 3 ) page: 579 - 583   2010.2

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    DOI: 10.1002/cphc.200900869

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  143. Angle-Independent Structural Color in Colloidal Amorphous Arrays Reviewed

    Harun-Ur-Rashid, M., Imran, A. B., Seki, T., Ishii, M., Nakamura, H., Takeoka, Y.

    ChemPhysChem.   Vol. 11   page: 579-583   2010

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  144. Characteristics of disperse poly(N-isopropylacrylamide) brushes on silicon surfaces by Atom transfer radical polymerization

    Huda, M.N., Seki, T., Suzuki, H., Kabir, A.N.M.H., Rashid, H.U., Takeoka, Y.

    Transactions of the Materials Research Society Japan   Vol. in press.   2010

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  145. Hydrophobic and hydrophilic polyrotaxane based movable cross-linkers for thermo-sensitive poly(N-isopropylacrylamide) gels Reviewed

    Imran, A. B., Seki, T., Ito, K., Takeoka, Y.

    Transactions of the Materials Research Society Japan   Vol. in press.   2010

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  146. Facile synthesis of sliding poly(NIPA) gels using a vinyl modified polyrotaxane as a Cross-linker Reviewed

      Vol. in press.   2010

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  147. Poly(N-isopropylacrylamide) gel prepared using a hydrophilic polyrotaxane-based movable cross-linker Reviewed

    Imran, A. B., Seki, T., Ito, K., Takeoka, Y.

    Macromolecules   Vol. 43   page: 1975-1980   2010

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  148. Characteristics of High-Density Poly(<i>N</i>-isopropylacrylamide) (PNIPA) Brushes on Silicon Surface by Atom Transfer Radical Polymerization

    Huda M.Nurul, Seki Takahiro, Suzuki Hiromasa, Kabir A.N.M Hamidul, Rashid M. Harunur, Takeoka Yukikazu

    Transactions of the Materials Research Society of Japan   Vol. 35 ( 4 ) page: 845-848 - 848   2010

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    High-density poly(<i>N</i>-isopropylacrylamide) (PNIPA) brushes were synthesized on silicon surfaces by surface initiated ATRP at various polymerization conditions. Polymerization was achieved using CuCl/tris(2-(dimethylamino)ethyl)amine (Me<sub>6</sub>TREN) as a catalytic system in DMSO at 20℃. The linear evolution of number average molecular weight (<i>M</i><sub>n</sub>) versus monomer conversion, the increase in layer thickness with polymerization time and relatively low molecular weight distribution (~ 1.2) indicate a well-controlled manner of polymerization. The average value of grafting density of PNIPA brushes was around 0.48 chain/nm<sup>2</sup>: We obtained high-density PNIPA brushes. During the measurement of air bubble contact angle under the surface of the PNIPA brushes in water, the surface property of PNIPA brushes shows an interesting phenomenon, which is antithetic to that of typical PNIPA gel. With the increase of temperature from 10℃, the surfaces of the PNIPA brushes gradually change to more hydrophobic natures. But as temperature approaches the LCST, the brush surfaces turned back to hydrophilic state. This might be the effect of the change in the surface morphology of the polymer brushes and/or the change in physical state of the terminal end groups of the polymer, depending on temperature.

    DOI: 10.14723/tmrsj.35.845

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  149. Facile synthesis of sliding poly(NIPA) gels using a vinyl modified polyrotaxane as a cross-linker

    Bin Imran Abu, Seki Takahiro, Ito Kohzo, Takeoka Yukikazu

    Transactions of the Materials Research Society of Japan   Vol. 35 ( 4 ) page: 841-844 - 844   2010

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    A unique hydrogel has been synthesized using supramolecular polyrotaxane as the starting material. Sparsely dispersed α-cyclodextrins threaded into long polyethylene glycol axle (Mw=35000) trapped with a stable capping agent, 1-adamantanamine of polyrotaxane (PR) unit was used for this purpose. The modification of the hydroxyl groups of α-CDs of the PR by a vinyl monomer containing an active isocyanate group at one end resulted in the formation of a stable carbamate bond with hydroxyl groups to give the modified polyrotaxane based cross-linker (MPR). Polymer gels were designed using MPR as a cross-linker and N-isopropylacrylamide, NIPA as a monomer and transparent, very soft, flexible, fast responsive and mechanically improved polymer gels could be obtained. The polymer chains can slide and rotate about the movable cross-linker in the gel network, which potentially improves the properties of the gels over conventional chemically cross-linked polymer gel.

    DOI: 10.14723/tmrsj.35.841

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  150. Hydrophobic and hydrophilic polyrotaxane based movable cross-linkers for thermo-sensitive poly(<i>N</i>-isopropylacrylamide) gels

    Imran Abu Bin, Seki Takahiro, Ito Kohzo, Takeoka Yukikazu

    Transactions of the Materials Research Society of Japan   Vol. 35 ( 2 ) page: 291-297 - 297   2010

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    A novel hydrogel has been fabricated using vinyl modified polyrotaxane as a cross-linker. A sparsely dispersed propylene oxide modified α-cyclodextrins which were threaded into the long polyethylene glycol (Mw = 35000) and were trapped by bulky 1-adamantanamine molecules was used as a hydrophilic polyrotaxane, HPR. HPR was modified by a small amount 2-acryloyloxyethylisocyanate monomer to obtain a water soluble polyrotaxane-based movable cross-linker, MHPR. Polymer gels, prepared by free radical polymerization of thermo-sensitive monomer <i>N</i>-isopropylacrylamide (NIPA) in presence of MHPR cross-linker, gave transparent, soft and flexible, mechanically strong and fast thermo-sensitive gels. The gel changes its volume isotropically and reaches rapidly to the equilibrium shrunken state after a temperature jump. The hydrophilicity of the cross-linker retains the homogeneity in the gel network and restricts the formation of aggregated globules, which permits the poly(NIPA) chains along with macrocycles to move or rotate freely inside the gel networks under deformation. The movability of the cross-links can strongly minimize their localized stress during deformation. The fascinating characteristics of the gel was compared and contrasted with the gels prepared using using hydrophobic polyrotaxane-based multifunctional and bi-functional <i>N,N’</i>-methylene-bis-acrylamide cross-linkers.

    DOI: 10.14723/tmrsj.35.291

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  151. Characteristics of disperse poly(N-isopropylacrylamide) brushes on silicon surfaces by Atom transfer radical polymerization

    Huda, M.N, Seki, T, Suzuki, H, Kabir, A.N.M.H, Rashid, H.U, Takeoka, Y

    Transactions of the Materials Research Society Japan   Vol. in press.   2010

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  152. Hydrophobic and hydrophilic polyrotaxane based movable cross-linkers for thermo-sensitive poly(N-isopropylacrylamide) gels Reviewed

    Imran, A. B, Seki, T, Ito, K, Takeoka, Y

    Transactions of the Materials Research Society Japan   Vol. in press.   2010

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  153. Facile synthesis of sliding poly(NIPA) gels using a vinyl modified polyrotaxane as a Cross-linker Reviewed

      Vol. in press.   2010

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  154. Confined Stimuli-Responsive Polymer Gel in Inverse Opal Polymer Membrane for Colorimetric Glucose Sensor Reviewed

    Masaki Honda, Kazunori Kataoka, Takahiro Seki, Yukikazu Takeoka

    LANGMUIR   Vol. 25 ( 14 ) page: 8349 - 8356   2009.7

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    We developed a totally synthetic colorimetric glucose-sensing system that is composed of glucose-responsive hydrogel particles confined in all inverse opal polymer membrane. This system exhibits structural color on the basis of Bragg diffraction arising from the 3-D ordered structure with periodicity on the order of the wavelength of visible light. The volume of the hydrogel particles reversibly changes as the glucose concentration varies in the separated pores of the inverse opal polymer membrane; this system reveals a reversible change in the color appearance and the peak intensity of the reflection spectra with the variation in the glucose concentration. By careful design of the system, we can detect the important range of glucose concentration around the threshold value for diagnosing diabetes mellitus by using the colorimetric glucose-sensing system.

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  155. Structural Colored Gel Invited Reviewed

    Takeoka, Y.

    J. Photopolymer Sci. & Tech.   Vol. 22   page: 123 - 132   2009

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  156. Electrochromism based on structural clour changes in a polyelectrolyte gel Reviewed

    Ueno, K., Sakamoto, J., Takeoka, Y. Watanabe, M.

    J. Mater. Chem.   Vol. 1   page: 4778-4783   2009

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  157. Structural Coloured Liquid Membrane without Angle-Dependence Reviewed

    Takeoka, Y. Honda, M., Seki, T., Ishii, M., Nakamura, H.

    ACS Applied Materials & Interfaces   Vol. 1   page: 982-986   2009

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  158. Template Synthesis for Stimuli-Responsive Angle Independent Structural ColoredSmart Materials Reviewed

    Harun-Ur-Rashid, M., Imran, A. B., Seki, T., Ishii, M., Nakamura, H., Takeoka, Y.

    Transactions of the Materials Research Society Japan   Vol. in press   2009

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  159. Confined Stimuli-Responsive Polymer Gel in Inverse Opal Polymer Membrane for Colorimetric Glucose sensor Reviewed

    Honda, M., Kataoka, K., Seki, T., Takeoka, Y.

    Langmuir   Vol. 25   page: 8349-8356   2009

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  160. *Dual Tuning of Photonic Band Gap Structure in Soft Photonic Crystal Reviewed

    Honda, M., Seki, T., Takeoka, Y.

    Adv. Mater.   Vol. 21   page: 1801-1804   2009

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  161. Structural Colored Gels for Tunable Soft Photonic Crystals Invited Reviewed

    Rashid, H.-u., Seki, T., Takeoka, Y.

    The Chemical Record   Vol. 9   page: 87-105   2009

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  162. Several Aggregation States Composed of Colloidal Particles: Application to Structural Colored Materials(<Special Issue>The Front Line of Pseudo-Crystalline Structures Formed by Complex Polymers)

    Takeoka Yukikazu

    Journal of the Japanese Association for Crystal Growth   Vol. 36 ( 1 ) page: 49-54 - 54   2009

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    Here, I show the fundamental optical behaviors of aggregation states of colloidal particles: colloidal crystal, colloidal amorphous, and colloidal quasi-crystal.

    DOI: 10.19009/jjacg.36.1_49

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  163. Structural Colored Gel

    Takeoka Yukikazu

    JOURNAL OF PHOTOPOLYMER SCIENCE AND TECHNOLOGY   Vol. 22 ( 2 ) page: 123-132   2009

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  164. Structural Colored Gel Reviewed

    Yukikazu Takeoka

    JOURNAL OF PHOTOPOLYMER SCIENCE AND TECHNOLOGY   Vol. 22 ( 2 ) page: 123 - 132   2009

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    A periodically ordered interconnecting porous structure can be embodied in a chemical gel by using a closest-packed colloidal crystal as a template. The interconnecting porosity not only provides a quick response but also endows the porous gel with structural color arising from coherent Bragg optical diffraction. The structural color revealed by porous gels can be regulated by several techniques, and thus it is feasible to obtain desirable, smart, soft materials. The swelling parameter of the polymer chains in the polymer network in response to the environment may be recognized through the variation in the color of the structural colored gel by using the fine colloidal crystal. The role of the volume interactions between the polymer chains in the gel can be estimated by simply measuring the length of the gel, based on the assumption that the subchains in the polymer network under the preparation conditions behave as unperturbed Gaussian coils. This means that it is possible to determine the change at the molecular level in the gel such as the swelling parameter of the polymer chains in the polymer network in response to the environment with the naked eye only when the gel is fabricated from specific a pre-gel solution and a colloidal crystal. The linear expansion factor of the subchains was assessed by comparing the positions of the diffraction peak (lambda(max)) in a given situation and the Gaussian state at temperatures lower than the LCST of the porous gel. The periodically ordered structure with a size corresponding to the wavelength of optical light allows us to detect the behavior of polymer chains through the structural color. This review focuses on the synthesis of the structural colored porous gel and on the visualizing conformations of subchains by creating optical wavelength-sized periodically ordered structure in hydrogel. The main portion of this article was previously published in Langmuir.(19)

    DOI: 10.2494/photopolymer.22.123

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  165. Structural Colored Gels for Tunable Soft Photonic Crystals Reviewed

    Mohammad Harun-Ur-Rashid, Takahiro Seki, Yukikazu Takeoka

    CHEMICAL RECORD   Vol. 9 ( 2 ) page: 87 - 105   2009

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    A periodically ordered interconnecting porous structure can be embodied in chemical gels by using closest-packed colloidal crystals as templates. The interconnecting porosity not only provides a quick response but also endows the porous gels with structural color arising from coherent Bragg optical diffraction. The structural colors revealed by porous gels can be regulated by several techniques, and thus, it is feasible to obtain desirable, smart, soft materials. A well-known thermosensitive monomer, N-isopropylacrylamide (NIPA), and other minor monomers were used to fabricate various structural colored gels. The selection of minor monomers depended on the targeted properties. This review focuses on the synthesis of templates, structural colored porous gels, and the applications of structural colored gel as smart soft materials for tunable photonic crystals. (D 2009 The Japan Chemical journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 87-105; 2009: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20169

    DOI: 10.1002/tcr.20169

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  166. Template Synthesis for Stimuli-Responsive Angle Independent Structural Colored Smart Materials

    Harun-Ur-Rashid Mohammad, Imran Abu Bin, Seki Takahiro, Takeoka Yukikazu, Ishii Masahiko, Nakamura Hiroshi

    Transactions of the Materials Research Society of Japan   Vol. 34 ( 2 ) page: 333-337 - 337   2009

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    Like other conventional smart materials, structural color showing smart materials inherit physical and chemical characteristics imposed by the templates. Smart Material such as structural colored gel made of photonic crystal (PC) as template, exhibits angle dependent structural color because the color arises from the Bragg optical diffraction of light from crystal planes. But angle independent or low angle dependent structural color is required for devising of display with a wide viewing angle. To meet this purpose we prepared photonic glass (PG) from silica colloidal spheres. This PG is able to exhibit structural color, which is stable against the change of the angle of view and the angle of illumination. The transmittance spectrum evidences the angle independence of the structural color of PG. The Fast Fourier Transformation and the autocorrelation function prove that we prepared an amorphous material. The existence of short range order helps PG to exhibit angle independent structural color.

    DOI: 10.14723/tmrsj.34.333

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  167. Template Synthesis for Stimuli-Responsive Angle Independent Structural ColoredSmart Materials Reviewed

    Harun-Ur-Rashid, M, Imran, A. B, Seki, T, Ishii, M, Nakamura, H, Takeoka, Y

    Transactions of the Materials Research Society Japan   Vol. in press   2009

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  168. Chromic slide-ring gel based on reflection from photonic bandgap Reviewed

    Harumi Murayama, Abu Bin Imran, Shusaku Nagano, Takahiro Seki, Masatoshi Kidowaki, Kohzo Ito, Yukikazu Takeoka

    MACROMOLECULES   Vol. 41 ( 5 ) page: 1808 - 1814   2008.3

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    Here we report on a chromic slide-ring gel consisting of polyrotaxane by using a close-packed colloidal crystal as a template. In the slide-ring gel, the polymer chains with bulky end groups are not covalently cross-linked like chemical gels nor do they interact attractively like physical gets, but are topologically interlocked by figure-of-eight cross-links. The slide-ring gel has freely movable cross-links, which have a pulley effect on tensile deformation. This effect improves the mechanical properties of polymer gels. In this work, this physically and mechanically optimized polymer gel was used to make stimuli-responsive photonic band gap materials. Our gel exhibits solvatochromic behavior based on the change in structural color.

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  169. *Photoregulated Worm-like Motion of Gel Reviewed

    Shinohara, S., Seki, T., Sakai, T., R. Yoshida, Takeoka, Y.

    Angew. Chem. Int. Ed.   Vol. 97   page: 9039-9043   2008

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  170. *Fabrication of Mechanically Improved Hydrogels Using Movable Cross-linker Based on Vinyl Modified Polyrotaxane Reviewed

    Imran, A. B., Seki, T., Kataoka, T., Kidowaki, M., Ito, K., Takeoka, Y.

    Chemical Communications     page: 5227-5229   2008

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  171. Chemical and Optical Control of Peristaltic Actuator Based on Self-Oscillating Porous Gel Reviewed

    Shinohara, S., Seki, T., Sakai, T., R. Yoshida, Takeoka, Y.

    Chemical Communications   Vol. 4735-4737   2008

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  172. Chromic Slide-Ring Gel based on Reflection from Photonic Bandgap Reviewed

    Murayama, H., Imran, A. B., Nagano, S., Seki, T., Kidowaki, M., Ito, K., Takeoka, Y.

    Macromolecules   Vol. 41   page: 1808-1814   2008

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  173. Chemical and optical control of peristaltic actuator based on self-oscillating porous gel Reviewed

    Shu-ichi Shinohara, Takahiro Seki, Takamasa Sakai, Ryo Yoshida, Yukikazu Takeoka

    CHEMICAL COMMUNICATIONS   Vol. 4735-4737 ( 39 ) page: 4735 - 4737   2008

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    We demonstrate the chemical and optical control of the self-sustaining peristaltic motion of a structural colored porous hydrogel.

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  174. Photoregulated wormlike motion of a gel Reviewed

    Shinohara Shu-ichi, Seki Takahiro, Sakai Takamasa, Yoshida Ryo, Takeoka Yukikazu

    Angewandte Chemie   Vol. 120 ( 47 ) page: 9179   2008

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  175. Photochromic gels

    TAKEOKA Yukikazu

    Photochemistry   Vol. 38 ( 2 ) page: 126-129   2007.9

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  176. Organized monolayer of thermosensitive microgel beads prepared by double-template polymerization Reviewed

    Takamasa Sakai, Yukikazu Takeoka, Takahiro Seki, Ryo Yoshida

    LANGMUIR   Vol. 23 ( 17 ) page: 8651 - 8654   2007.8

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    A 2D close-packed array of thermosensitive microgel beads was prepared by the double-template polymerization method. First, a 2D colloidal crystal of silica beads with 10 mu m diameter was obtained by the solvent evaporation method. This monolayer of colloidal crystals can serve as the first template for the preparation of macroporous polystyrene. The macroporous polystyrene trapping the crystalline order can be used as a negative template for fabricating gel beads arrays. A functional surface using thermosensitive poly(N-isopropylacrylamide) gel beads array was fabricated by the double-template polymerization method.

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  177. Photoresponsive slide-ring gel Reviewed

    Taiga Sakai, Harumi Murayama, Shusaku Nagano, Yukikazu Takeoka, Masatoshi Kidowaki, Kohzo Ito, Takahiro Seki

    ADVANCED MATERIALS   Vol. 19 ( 15 ) page: 2023 - +   2007.8

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    Slide-ring topological gels with mobile cross-linking units are a new class of soft materials that exhibit distinct features differing from those of conventional chemically or physically crosslinked gels. Photoresponsive behavior arising from the dynamic nature of the cross-linkers is demonstrated for a slide-ring, gel prepared by adding azobenzene units to the mobile a-cyclodextrin units of a poly(ethylene oxide)based polyrotaxane (see figure).

    DOI: 10.1002/adma.200700457

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  178. Biform structural colored hydrogel for observation of subchain conformations Reviewed

    Yukikazu Takeoka, Takahiro Seki

    MACROMOLECULES   Vol. 40 ( 15 ) page: 5513 - 5518   2007.7

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    We prepared a biform structural colored thermosensitive gel using both a close-packed colloidal crystal and a wing of a morpho butterfly. The porous portion of the gel obtained by the close-packed colloidal crystal as a template exhibits a change in "structural color" according to the volume when the water temperature is altered. Meanwhile, the portion where tiny scales of the wing are strewn on the surface of the gel (a morpho gel) also reveals "structural color", but irrespective of the volume change. The reflection spectrum from "the morpho gel" portion provides the standard value of the peak position, lambda(max,0), indicating that the subchains in the gel are Gaussian chains. Consequently, we can estimate the linear expansion factor alpha of the subchains by comparing the peak positions of the reflection spectra from the porous gel, lambda(max), and from the morpho gel, lambda(max,0): lambda(max)/lambda(max,0) similar to alpha. We can detect the change in the conformation of subchains in the gel in response to the external perturbations surrounding the gel with the naked eye and/or spectroscopic methods through the comparison of the both structural colors.

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  179. Organized Thermosensitive Microgel Bead Monolayer Prepared by Double Template Polymerization

    SAKAI Takamasa, TAKEOKA Yukikazu, SEKI Takahiro, YOSHIDA Ryo

      Vol. 64 ( 1 ) page: 45-49   2007.1

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  180. Volume Phase Transition of Gel (1978 : Toyoichi Tanaka)

    NAGAYAMA Kuniaki, TAKEOKA Yukikazu

    Kobunshi   Vol. 56 ( 1 ) page: 26-27 - 27   2007.1

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    DOI: 10.1295/kobunshi.56.26

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  181. *Thermally-Adjustable Multicolor Photochromic Hydrogel Reviewed

    Matsubara, K., Watanabe, M., Takeoka, Y.

    Angew. Chem. Int. Ed.   Vol. 46   page: 1688-1692   2007

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  182. Organized monolayer of thermosensitive microgel beads prepared bydouble template polymerization Reviewed

    Sakai, T., Takeoka, Y., Seki, T., Yoshida, R.

    Langmuir   Vol. 23   page: 8651-8654   2007

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  183. Photoresponsive Slide-Ring Gel Reviewed

    Sakai, T. Murayama, H., Nagano, S., Takeoka, Y., Kidowaki, M., Ito, K., Seki, T.

    Adv. Mater.   Vol. 23   page: 8651-8654   2007

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  184. Biform Structural Colored Hydrogel For Observation of Subchain Conformations Reviewed

    Takeoka, Y., Seki, T.

    Macromolecules   Vol. 40   page: 5513-5518   2007

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  185. 二段階鋳型重合法を用いた温度応答型ゲル微粒子単層組織化膜の作製 Reviewed

    酒井崇匡、竹岡敬和、関 隆広、吉田 亮

    高分子論文集   Vol. 64   page: 45-49   2007

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  186. *Electro- and Thermo- chromic Hydrogel as Full-color Indicator Reviewed

    Ueno, K., Matsubara, K., Watanabe, M., Takeoka, Y.

    Adv. Mater.   Vol. 19   page: 2807-2812   2007

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  187. Organized thermosensitive microgel bead monolayer prepared by double template polymerization Reviewed

    Takamasa Sakai, Yukikazu Takeoka, Takahiro Seki, Ryo Yoshida

    KOBUNSHI RONBUNSHU   Vol. 64 ( 1 ) page: 45 - 49   2007

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    A 2D close-packed array of thermosensitive microgel beads was prepared by a double template polymerization method. Firstly, colloidal crystals of silica beads were obtained by solvent evaporation method. A concave and rather flat meniscus was formed at liquid-air interface by using O-rings. This monolayer of colloidal crystal can serve as the first template for preparation of macroporous polystyrene. The macroporous polymer template that trapped the crystalline order was soaked in pre-gel solution as the second template, and then polymerization was carried out in the pores. By etching the surrounding polystyrene template, we obtained a 2D monolayer of thermosensitive microgel beads. The 2D monolayer of the gel beads may be utilized as a functional surface for several applications to optical device and biomaterials.

    DOI: 10.1295/koron.64.45

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  188. A thermally adjustable multicolor photochromic hydrogel

    Matsubara Kazuki, Watanabe Masayoshi, Takeoka Yukikazu

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 46 ( 10 ) page: 1688-1692   2007

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    DOI: 10.1002/anie.200603554

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  189. A thermally adjustable multicolor photochromic hydrogel

    Matsubara Kazuki, Watanabe Masayoshi, Takeoka Yukikazu

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 46 ( 10 ) page: 1688-1692   2007

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    DOI: 10.1002/anie.200603554

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  190. A thermally adjustable multicolor photochromic hydrogel

    Matsubara Kazuki, Watanabe Masayoshi, Takeoka Yukikazu

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 46 ( 10 ) page: 1688-1692   2007

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    DOI: 10.1002/anie.200603554

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  191. Organized thermosensitive microgel bead monolayer prepared by double template polymerization

    Sakai Takamasa, Takeoka Yukikazu, Seki Takahiro, Yoshida Ryo

    KOBUNSHI RONBUNSHU   Vol. 64 ( 1 ) page: 45-49   2007

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  192. 二段階鋳型重合法を用いた温度応答型ゲル微粒子単層組織化膜の作製 Reviewed

    酒井崇匡, 竹岡敬和, 関 隆広, 吉田 亮

    高分子論文集   Vol. 64   page: 45-49   2007

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  193. Visualizing conformations of subchains by creating optical wavelength-sized periodically ordered structure in hydrogel Reviewed International journal

    Yukikazu Takeoka, Takahiro Seki

    LANGMUIR   Vol. 22 ( 24 ) page: 10223 - 10232   2006.11

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    Thick single-crystalline fcc colloidal crystals exhibiting structural color are obtained by a solvent evaporation method from silica colloidal particle suspensions. A periodically ordered interconnecting porous structure can be imprinted in thermosensitive N-isopropylacrylamide (NIPA) gels by using the colloidal crystals as templates. The porous structure endows a structural color to the NIPA gels. We find that the peak position of the reflection spectra from the porous gels (lambda(max)') is expressed as a function of the swelling degree and is synchronized with the change in the swelling degree. The color can be precisely tuned by simply changing the amount of the monomer and the cross-linker in the pre-gel solutions. We can estimate the linear expansion factor alpha (>= 1) of the subchains by comparing the peak position at a given situation (lambda(max)') and the reference state (lambda(max,0)'), in which the subchains behave as Gaussian coils. Creating the periodically ordered structure, which is similar in size to the wavelength of optical light, in the gels allows us to determine the behavior of polymer chains by observing the structural color.

    DOI: 10.1021/la061945i

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  194. Visualizing Conformations of Subchains in Structural Colored Gel

    TAKEOKA Yukikazu

    MEMBRANE   Vol. 31 ( 6 ) page: 296-301 - 301   2006.11

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    We prepared porous polymer gels using a colloidal crystal as a template. The porous structure endows a structural
    color to polymer gels. We found that the peak position of the reflection spectra from the porous gels (λmax) is
    expressed as a function of the swelling degree, and is synchronized with the change in the swelling degree. We can
    estimate the linear expansion factor α of the subchains by comparing the peak position at a given situation (λmax)
    and the reference state (λmax, 0), in which the subchains behave as Gaussian coils. Creating the periodically ordered structure, which is similar in size to the wavelength of optical light, in the gels allows us to determine the behavior of polymer chains by observing the structural color.

    DOI: 10.5360/membrane.31.296

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  195. Preparations and optical properties of. ordered arrays of submicron gel particles: Interconnected state and trapped state International journal

    M Kumoda, M Watanabe, Y Takeoka

    LANGMUIR   Vol. 22 ( 9 ) page: 4403 - 4407   2006.4

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    Two types of thermosensitive opal-structured hydrogel systems, "interconnected" and "trapped" gel particle arrays, were newly developed by extremely simple methods using silica colloidal crystal as a template. Although both systems diffract visible light following Bragg's law combined with Snell's law, the temperature dependences of their optical properties were quite different. The "interconnected" array exhibited a reversible change in the peak values of the reflection spectra, mainly determined by the swelling ratio of the hydrogel, as a function of the water temperature. Since the swelling ratio is dominant over the peak value, we can observe water temperature through the color of the interconnected type of gel membrane. The "trapped" array revealed a reversible change in the peak intensity of the reflection spectra with the change in temperature, whereas no change in the peak position was observed. We can interpret this phenomenon in the following ways. As the rise in temperature causes a decrease in the water content of the NIPA gel particles, the gel particles becomes stickier on the cavity wall of polystyrene PPM. This may induce a disturbance in the ordered array of the gel particles and form many layers of rough surfaces in the inverse opal structure of the PPM. This situation may lead to the stronger diffused reflection of light from the gel particles, resulting in the decrease in peak intensity at higher temperatures.

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  196. Visualizing Conformations of Subchains by Creating Optical Wavelength-Sized Periodically Ordered Structure in Hydrogel Reviewed

    Takeoka, Y. and Seki, T.

    Langmuir   Vol. 22   page: 10223-10232   2006

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  197. Preparations and optical properties of ordered arrays of submicron gel particles: Interconnected state and trapped state Reviewed

    Kumoda, M., Watanabe, M., Takeoka, Y.

    Langmuir   Vol. 22   page: 4403-4407   2006

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  198. Photomechanical effect of azobenzene liquid crystalline gel impregnated with low molecular weight liquid crystals.

    HAYATA Yuki, NAGANO Shusaku, TAKEOKA Yukikazu, SEKI Takahiro

    Proceedings of Japanese Liquid Crystal Society Annual meeting   Vol. 2006 ( 0 ) page: 175-175 - 175   2006

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    Crosslinked side-chain liquid crystalline gels thin films containing azobenzene moieties were prepared by photopolymerized under visible light (436 nm) irradiation in the liquid crystalline state. The monodomain and polydomain gels were prepared on a rubbed and non-rubbed polymer film, respectively. Swelling and shrinkage in low molecular weight liquid crystal solvents were induced by the photoisomerization of azobenzene. Because the amount of azobenzene moieties were lowered to 3 wt%, the whole volume changed, and the photoisomerization behavior could be precisely evaluated by optical microscopy and UV-Vis spectroscopy.

    DOI: 10.11538/ekitou.2006.0.175.0

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  199. Ionic conductivity and thermal stability of room temperature molten salts perfluorosulfonic acid membranes for fuel cell application Reviewed

    S Mitsushima, R. Sakamoto, K. Kudo, Y. Takeoka, N. Kamiya, and Ken-ichi Ota

    J. New Materials for Electrochem. Sys.   Vol. 1   page: 77-84   2005

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  200. 高分子科学最近の進歩 構造色ゲル

    竹岡 敬和

    高分子   Vol. 54 ( 4 ) page: 258-263 - 263   2005

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    DOI: 10.1295/kobunshi.54.258

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  201. Surface activity and redox behavior of a non-ionic surfactant containing a phenothiazine group

    MABH Susan, A Ishibashi, Y Takeoka, M Watanabe

    COLLOIDS AND SURFACES B-BIOINTERFACES   Vol. 38 ( 3-4 ) page: 167 - 173   2004.11

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    A novel non-ionic surfactant, alpha-(phenothiazinylhexyl)-omega-hydroxy-oligo(ethylene oxide) (PCPEG) containing phenothiazine as an electroactive group has been synthesized. Fundamental interfacial behavior of the surfactant at the air/water interface has been investigated by means of surface tensiometry to provide an insight into the relationship between the structure of the hydrophobic moiety and the surfactant properties. A comparison of diffusivity of PCPEG in the aqueous phase with that in the acetonitrile solution at high PCPEG concentrations shows that micellization has a pronounced effect on the redox behavior of PCPEG. The electrochemical responses for PCPEG aqueous solutions at the interface of a glassy carbon electrode are fairly dependent on the concentration of PCPEG. Above CMC, PCPEG molecules self-associate to form micellar aggregates and the formation and disruption of micelles can be reversibly controlled by change in the redox state of the phenothiazine group. The cyclic voltammetric responses for PCPEG aqueous solutions have been correlated with the dissolved states to explain the distinctive feature of the surfactant. (C) 2004 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.colsurfb.2004.01.016

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    PubMed

  202. Structural Colored Gel

    TAKEOKA Yukikazu, WATANABE Masayoshi

    NIPPON GOMU KYOKAISHI   Vol. 77 ( 5 ) page: 155-158 - 158   2004.5

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:THE SOCIRETY OF RUBBER SCIENCE AND TECHNOLOGYY, JAPAN  

    A periodically ordered interconnecting porous structure could be imprinted in hydrogels by using closest packing silica colloidal crystals as mesoscopically sized templates. The interconnecting porous structure provides fast response to an infinitesimal change of environment for reversible swelling and shrinking of the hydrogels, while the periodically ordered mesoscopical structure endows a structural color in the gel. The structural color with different optical behaviors can be tuned by simply changing the amount of the cross-linker in the pre-gel solutions. The structural color imprinted in the gel is quickly synchronized with the change in the volume of the gels. The newly invented porous hydrogels possess optical properties as environmentally sensitive smart gels.

    DOI: 10.2324/gomu.77.155

    CiNii Research

  203. Surface activity and redox behavior of a non-ionic surfactant containing a phenothiazine group Reviewed

    Susan, M.A.B.H., Ishibashi, A., Takeoka, Y. and Watanabe, M.

    Colloids and Surfaces B-Biointerfaces   Vol. 38   page: 167-173   2004

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  204. Controlled multistructural color of a gel membrane Reviewed

    Y Takeoka, M Watanabe

    LANGMUIR   Vol. 19 ( 23 ) page: 9554 - 9557   2003.11

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    A "smart" soft membrane exhibiting controlled multistructural color has been synthesized by the mechanical immobilization of a single side of a polymerized nonclosest packing colloidal crystal. A tapered gel with one fixed surface on a gel-bond film reveals monostructural color. After a partial hydrolysis of the gel to change its volume from the original size, the structural color varies depending on the thickness of the membrane. The tone can be tuned by simply changing the composition of the mixed solvent.

    DOI: 10.1021/la0344175

    Web of Science

  205. Self-sustaining peristaltic motion on the surface of a porous gel

    Y Takeoka, M Watanabe, R Yoshida

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   Vol. 125 ( 44 ) page: 13320 - 13321   2003.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    Many materials in living organisms exhibit self-sustaining<br />
    oscillations of chemical and/or physical organization,<br />
    for example,the peristaltic motion of the intestinal tract.<br />
    Some artificial materials have similar properties and thus the<br />
    potential for mimicking biological functions.Now researchers in<br />
    Japan have developed a polymer-gel system that undergoes<br />
    colour changes such that the oscillations can be observed on the<br />
    surface of the gel for the first time (Takeoka,Y.,Watanabe,M.&amp;<br />
    Yoshida,R.Journal of the American Chemical Society 125,<br />
    13320.V13321; 2003).The gel consists of two monomers,<br />
    N-isopopylacrylamide,which controls the swelling and collapse<br />
    of the gel in response to temperature,and a Ru-complex.<br />
    Under certain chemical conditions,the Ru-complex ion<br />
    catalyses a specific reaction (BZ) in which the ion is alternately<br />
    oxidized and reduced as the reaction propagates,resulting in<br />
    colour changes.When the gel is simultaneously subjected to<br />
    changes in temperature,the swelling response of the gel<br />
    occurs in parallel with the BZ reaction,resulting in waves of colour<br />
    changes concomitant with the peristaltic motion.The colour<br />
    tunability of these gels have the potential for use in devices

    DOI: 10.1021/ja036904c

    Web of Science

    PubMed

  206. Tuning structural color changes of porous thermosensitive gels through quantitative adjustment of the cross-linker in pre-gel solutions Reviewed

    Y Takeoka, M Watanabe

    LANGMUIR   Vol. 19 ( 22 ) page: 9104 - 9106   2003.10

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    "Smart" porous gels with different optical behaviors were synthesized by quantitative adjustment of the cross-linker in pre-gel solutions. A periodically ordered interconnecting porous structure could be created in the gels by using a closest-packing silica colloidal crystal as a template. The interconnecting porosity provides fast response to changes in temperature through the reversible swelling and shrinking of the gels, while the periodically ordered mesoscopic structure endows the porous gels with structural color, which can be tuned by simply changing the amount of the cross-linker in the pre-gel solutions.

    DOI: 10.1021/la035142w

    Web of Science

  207. Template synthesis and optical properties of chameleonic poly(N-isopropylacrylamide) gels using closest-packed self-assembled colloidal silica crystals Reviewed

    Y Takeoka, M Watanabe

    ADVANCED MATERIALS   Vol. 15 ( 3 ) page: 199 - +   2003.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    Smart macroporous hydrogels with a range of optical behavior have been prepared using colloidal crystals as templates. The structural color imprinted in the gel (see Figure and cover) varies with a change in the volume of the gel. It is now possible to build a soft material that displays the various structural colors available to living things.

    Web of Science

  208. Template synthesis of poly(N-isopropylacrylamide) minigels using interconnecting macroporous polystyrene Reviewed

    M Kumoda, Y Takeoka, M Watanabe

    LANGMUIR   Vol. 19 ( 3 ) page: 525 - 528   2003.2

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    Thermosensitive uniform-sized poly(N-isopropylacrylamide) minigels with diameters of several micrometers were synthesized by a double template method using silica particles as original molds. The first template composed of the silica particles produced a macroporous polystyrene as the second template to decide the shape and the size of the minigels. The resultant minigels in the second template covalently interconnect with each other. After the minigels were collapsed in each compartment of the macroporous polystyrene, the separated minigel particles were obtained.

    DOI: 10.1021/la020758r

    Web of Science

  209. Polymer Gels that Memorize Structures of Mesoscopically Sized Templates Reviewed

    Takeoka, Y, Watanabe, M

    Langmuir   Vol. 18   page: 5977-5980   2003

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  210. Simple and precision design of porous gel as a visible indicator for ionic species and concentration Reviewed

    H Saito, Y Takeoka, M Watanabe

    CHEMICAL COMMUNICATIONS   ( 17 ) page: 2126 - 2127   2003

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

    Here we report the design and synthesis of a novel porous gel for an ionic visible indicator. The rapid-responsive porous gel which reveals color changes depending on a potassium ion concentration was prepared using a templating technique.

    DOI: 10.1039/b304306a

    Web of Science

  211. Self-Sustaining Peristaltic Motion on the Surface of a Porous Gel Reviewed

    Takeoka, Y., Watanabe, M., and Yoshida, R.

    J. Am. Chem. Soc   Vol. 125   page: 13320   2003

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    Many materials in living organisms exhibit self-sustaining
    oscillations of chemical and/or physical organization,
    for example,the peristaltic motion of the intestinal tract.
    Some artificial materials have similar properties and thus the
    potential for mimicking biological functions.Now researchers in
    Japan have developed a polymer-gel system that undergoes
    colour changes such that the oscillations can be observed on the
    surface of the gel for the first time (Takeoka,Y.,Watanabe,M.&
    Yoshida,R.Journal of the American Chemical Society 125,
    13320.V13321; 2003).The gel consists of two monomers,
    N-isopopylacrylamide,which controls the swelling and collapse
    of the gel in response to temperature,and a Ru-complex.
    Under certain chemical conditions,the Ru-complex ion
    catalyses a specific reaction (BZ) in which the ion is alternately
    oxidized and reduced as the reaction propagates,resulting in
    colour changes.When the gel is simultaneously subjected to
    changes in temperature,the swelling response of the gel
    occurs in parallel with the BZ reaction,resulting in waves of colour
    changes concomitant with the peristaltic motion.The colour
    tunability of these gels have the potential for use in devices used
    for determining oscillations in nonlinear chemical reactions.

  212. Controlled Multi-Structural-Color of a Gel Membrane Reviewed

    Takeoka, Y. and Watanabe, M.

    Langmuir   Vol. 19   page: 9554-9557   2003

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  213. Polymer Gels that Memorize Structures of Mesoscopically Sized Templates Reviewed

    Takeoka, Y. and Watanabe, M.

    Langmuir   Vol. 18   page: 5977-5980   2003

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  214. Template synthesis of poly(N-isopropylacrylamide) minigels using interconnecting macroporous polystyrene Reviewed

    Kumoda, M., Takeoka, Y. and Watanabe, M.

    Langmuir   Vol. 19   page: 525-528   2003

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  215. Template synthesis and optical properties of chameleonic poly(N-isopropylacrylamide)gels using closest-packed self-assembled colloidal silica crystals Reviewed

    Takeoka, Y. and Watanabe, M.

    Adv. Mater,   Vol. 15   page: 199-201   2003

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  216. Simple and Precision Preparation of Porous Gel for Colorimetric Chemical Sensor by Templating Technique Reviewed

    Nakayama, D., Takeoka, Y., Watanabe, M., Kataoka, K.

    Angew. Chem. Int. Ed.   Vol. 42   page: 4197-4200   2003

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  217. Tuning Structural Color Changes of Porous Thermo-sensitive Gels Through Quantitative Adjustment of The Cross-linker in Pre-gel Solutions Reviewed

    Takeoka, Y. and Watanabe, M.

    Langmuir   Vol. 19   page: 9104-9106   2003

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  218. Simple and precision design of porous gel as a visible indicator for ionic species and concentration Reviewed

    Saito, H., Takeoka, Y. and Watanabe, M.

    Chem. Commun.     page: 2126-2127   2003

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  219. Simple and precise preparation of a porous gel for a colorimetric glucose sensor by a templating technique

    D Nakayama, Y Takeoka, M Watanabe, K Kataoka

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 42 ( 35 ) page: 4197 - 4200   2003

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    DOI: 10.1002/anie.200351746

    Web of Science

    PubMed

  220. Reversible adsorption of calcium ions by imprinted temperature sensitive gels Reviewed

    C Alvarez-Lorenzo, O Guney, T Oya, Y Sakai, M Kobayashi, T Enoki, Y Takeoka, T Ishibashi, K Kuroda, K Tanaka, GQ Wang, AY Grosberg, S Masamune, T Tanaka

    JOURNAL OF CHEMICAL PHYSICS   Vol. 114 ( 6 ) page: 2812 - 2816   2001.2

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    With the aim of developing polymeric gels sensitive to external stimuli and able to reversibly adsorb and release divalent ions, copolymer gels of N-isopropylacrylamide (NIPA) and methacrylic (MAA) monomers were prepared. We chose calcium as a target divalent ion. Two MAAs form a complex with a calcium ion, and the NIPA component allows the polymers to swell and shrink reversibly in response to temperature. The adsorbing site develops an affinity to target ions when the adsorbing molecules come into proximity, but when they are separated, the affinity diminishes. To enhance the affinity to calcium, an imprinting technique was applied using Ca2+ and Pb2+ ions as templates in methylsulfoxide and dioxane media, respectively. The adsorption capacity of the imprinted gels was compared with that of the nonimprinted gels, and the effects of the templates, the solvents, and the amount of methacrylic monomers used in the synthesis and the medium temperature over the Ca2+ adsorption capacity of the gels from aqueous solutions were evaluated. The analysis of the adsorption revealed that (a) the adsorption can be described by the Langmuir isotherms; (b) there is an approximately linear relationship between saturation and methacrylic monomer concentration; (c) the affinity depends on the degree of gel swelling or shrinkage that can be switched on and off by temperature; (d) in the shrunken state, the affinity depends approximately linearly on the MAA concentration in the imprinted gels, whereas in the nonimprinted gels it is proportional to the square of MAA concentration; (e) the imprinted gels adsorb more than the nonimprinted gels when MAA concentration is less than that of permanent cross linkers. The success of imprinting of CaMAA(2) and PbMAA(2) complex is evidence for memory of such complex onto the weakly cross-linked gel. (C) 2001 American Institute of Physics.

    Web of Science

  221. Reversible adsorption of calcium ions by imprinted temperature sensitive gels Reviewed

    Carmen Alvarez-Lorenzo, Orhan Guney, Taro Oya, Yasuzo Sakai, Masatoshi Kobayashi, Takashi Enoki, Yukikazu Takeoka, Toru Ishibashi, Kenichi Kuroda, Kazunori 8Tanaka, Guoqiang Wang, Alexander Yu. Grosberg, Satoru Masamune, and Toyoichi Tanaka

    J. Chem. Phys.   Vol. 114 ( 6 ) page: 2812-2816   2001

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  222. Frustrations in polymer conformation in gels and their minimization through molecular imprinting Reviewed

    T Enoki, K Tanaka, T Watanabe, T Oya, T Sakiyama, Y Takeoka, K Ito, GQ Wang, M Annaka, K Hara, R Du, J Chuang, K Wasserman, AY Grosberg, S Masamune, T Tanaka

    PHYSICAL REVIEW LETTERS   Vol. 85 ( 23 ) page: 5000 - 5003   2000.12

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    We report an experimental realization of a gel system in which frustrations exist and can be minimized, thus meeting two crucial criteria predicted to enable memory of conformations in polymers. The gels consist of a thermosensitive major monomer component and two minor components. One minor component is positively charged and will form complexes around negatively charged target molecules placed in solution. The complexes can be imprinted into the gel by then cross-linking the second minor component, which will form cross-links additional to those in the major polymer matrix. The complexes are destroyed and reformed upon swelling and reshrinking of the gels, showing that memorization has been achieved.

    Web of Science

  223. Polymer gels that memorize elements of molecular conformation Reviewed

    C Alvarez-Lorenzo, O Guney, T Oya, Y Sakai, M Kobayashi, T Enoki, Y Takeoka, T Ishibashi, K Kuroda, K Tanaka, GQ Wang, AY Grosberg, S Masamune, T Tanaka

    MACROMOLECULES   Vol. 33 ( 23 ) page: 8693 - 8697   2000.11

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    Weakly cross-linked heteropolymer gels that memorize molecular pairs have been designed and synthesized. The polymer consists of a main monomer component responsible for volume phase transition, methacrylic acid that adsorbs one divalent ion as a pair, and cross-links; The memory of pairing of methacrylic acids within the gels was encoded in the primary sequence of main monomers, methacrylic acids and cross-links within the gels, which was achieved by "imprinting", namely, by synthesizing gels while methacrylic monomers were paired prior to polymerization. The control gels, where methacrylic monomers were randomly distributed, showed frustration in forming pairs, whereas such frustration was completely diminished in the imprinted gels allowing the memory of pair formation.

    Web of Science

  224. Gel catalysts that switch on and off Reviewed

    GQ Wang, K Kuroda, T Enoki, A Grosberg, S Masamune, T Oya, Y Takeoka, T Tanaka

    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA   Vol. 97 ( 18 ) page: 9861 - 9864   2000.8

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    We report development of a polymer gel with a catalytic activity that can be switched on and off when the solvent composition is changed. The gel consists of two species of monomers. The major component, N-isopropylacrylamide, makes the gel swell and shrink in response to a change in composition of ethanol/water mixtures. The minor component, vinylimidazole, which is capable of catalysis, is copolymerized into the gel network. The reaction rate for catalytic hydrolysis of p-nitrophenyl caprylate was small when the gel was swollen. In contrast, when the gel was shrunken, the reaction rate increased 5 times. The activity changes discontinuously as a function of solvent composition, thus the catalysis can be switched on and off by an infinitesimal change in solvent composition. The kinetics of catalysis by the gel in the shrunken state is well described by the Michaelis-Menten formula, indicating that the absorption of the substrate by the hydrophobic environment created by the N-isopropylacrylamide polymer in the shrunken gel is responsible for enhancement of catalytic activity, In the swollen state, the rate vs. active site concentration is linear, indicating that the substrate absorption is not a primary factor determining the kinetics, Catalytic activity of the gel is studied for substrates with various alkyl chain lengths; of those studied the switching effect is most pronounced for p-nitrophenyl caprylate.

    Web of Science

  225. Study of the correlation of the cyclic voltammetric responses of a nonionic surfactant containing an anthraquinone group with the dissolved states Reviewed

    Md. Abu Bin Hasan Susan, Mahbuba Begum, Yukikazu Takeoka, Masayoshi Watanabe

    Langmuir   Vol. 16 ( 7 ) page: 3509 - 3516   2000.4

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ACS  

    Cyclic voltammetric behavior of a nonionic surfactant, α-(anthraquinonyloxyhexyl)-ω-hydroxy-oligo-(ethylene oxide), ACPEG, has been studied in detail in aqueous media with NaCl as the supporting electrolyte. Attempts have been made to correlate the electrochemical responses with the dissolved states of the surfactant. The shapes of the cyclic voltammograms at a glassy carbon electrode have proved to be fairly dependent on the concentration of ACPEG and on the redox state of the anthraquinone group. Below the critical micelle concentration (cmc), the cyclic voltammogram (v = 10 mV/s) corresponds to the surfactant molecules adsorbed onto the electrode surface. The adsorption of ACPEG molecules at the electrode surface is very weak in nature owing to its low surface activity. A high cmc value and weak adsorption allow diffusion of the monomeric species prior to the reduction to contribute to the total current even below the cmc. At concentrations higher than the cmc, the diffusion-controlled waves are superimposed on the surface waves, and far above the cmc, the voltammetric shape is of a typical diffusion-controlled species. Above the cmc, self-association of ACPEG results in the formation of micellar aggregates, which diffuse to the electrode surface to dominate the adsorption wave. The redox process is influenced by the formation of a quinhydrone-like charge transfer complex. The cyclic voltammetrically determined apparent diffusion coefficient of the micellar solutions changes continuously with concentration
    with decreasing concentration the apparent diffusion coefficient approaches the monomeric diffusion coefficient while with increasing concentration it approaches the micellar value. This has been interpreted in terms of change in the diffusion species by dissociation of the micelles formed above the cmc to monomers in the concentration gradient in the diffusion layers. The formation and dissociation reaction can be reversibly controlled by a change in the redox state. A CEC mechanism with the electrochemical reaction coupled with the preceding disruption reaction of the micelles (CE) and the following protonation reaction of the reduced state (EC) has been inferred.

    DOI: 10.1021/la991033z

    Scopus

  226. Effect of pH and the extent of micellization on the redox behavior of non-ionic surfactants containing an anthraquinone group Reviewed

    MA Susan, M Begum, Y Takeoka, M Watanabe

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   Vol. 481 ( 2 ) page: 192 - 199   2000.2

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    Cyclic voltammetry has been employed for the study of aqueous electrochemistry of the surfactants, alpha-(anthraquinonyloxyhexyl)-omega-hydroxy-oligo(ethylene oxide) (ACPEG) and alpha-anthraquinonyl-omega-hydroxy-oilgo (ethylene oxide) (APEG), which have wide differences in surface activity. Potential-pH diagrams have been constructed and the various features of the diagrams have been analyzed in the light of the change in solution equilibria and the difference in the extent of micellization. The redox potentials of the surfactants have been found to exhibit strong pH dependence. The electrode reaction involves two-electron reduction of anthraquinone (AQ) to its dianion (AQ(2-)), which is highly sensitive to the pH of the solution. At controlled pH, potential-pH plots allow the establishment of the values of the ionization constants for dihydroanthraquinone (AQH(2)) and its monoanion (AQH(-)) as pK(a)(1) = 7.83 and pK(a)(2) = 11.38, respectively. Under unbuffered conditions, the effective pH close to the electrode surface controls the potential of the electrode process. The changeover from the H+-available to the H+-depleted electrode process gives rise to a sudden jump in potential. In highly alkaline solutions, AQ forms an adduct with hydroxyl ion, which causes a linear decrease in the potentials with increase in pH. The different extent of micellization results in a difference in the peak current and the half wave potentials (E-1/2) for ACPEG and APEG but causes no significant change in the shapes of the E-1/2-DH diagrams. This has been explained in terms of the disruption reaction of the micelles, preceding the electrochemical reaction. (C) 2000 Elsevier Science S.A. All rights reserved.

    Web of Science

  227. A study to correlate the electrochemical responses of a non-ionic surfactant containing an anthraquinine group with the dissolved states Reviewed

    Susan, M.A.B.H, Begum, M, Takeoka, Y, Watanabe, M

    Langmuir   Vol. 16   page: 3509-3516   2000

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  228. Frustrations in polymer conformation in gels and their minimization through molecular imprinting Reviewed

    Takashi Enoki, Kazunori Tanaka, Tsuyoshi Watanabe, Taro Oya, Takaharu Sakiyama, Yukikazu Takeoka, Kenji Ito, Guoqiang Wang, Masahiko Annaka, Kazuhiro Hara, Rose Du, Jeffrey Chuang, Kevin Wasserman, Alexander Yu. Grosberg, Satoru Masamune, and Toyoichi Tanaka

    Phys. Rev. Lett.   Vol. 85   page: 5000-5003   2000

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  229. A study to correlate the electrochemical responses of a non-ionic surfactant containing an anthraquinine group with the dissolved states Reviewed

    Susan, M.A.B.H., Begum, M., Takeoka, Y. and Watanabe, M.

    Langmuir   Vol. 16   page: 3509-3516   2000

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  230. Effect of pH and the extent of micellization on the redox behavior of non-ionic surfactants containing an anthraquinone group Reviewed

    Susan, M.A.B.H., Begum, M., Takeoka, Y. and Watanabe, M.

    J. Electroanal. Chem.   Vol. 481   page: 192-199   2000

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  231. Polymer Gels That Memorize Elements of Molecular Conformation Reviewed

    Alvarez-Lorenzo, Carmen; Guney, Orhan; Oya, Taro; Sakai, Yasuzo; Kobayashi, Masatoshi; Enoki, Takashi; Takeoka, Yukikazu; Ishibashi, Toru; Kuroda, Kenichi, Alexander Grosberg, and Toyoichi Tanaka

    Macromolecules   Vol. 33   page: 8693-8697   2000

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  232. Gel catalysts that switch on and off Reviewed

    Guoqiang Wang, Kenichi Kuroda, Takashi Enoki, Alexander Grosberg, Satoru Masamune, Taro Oya, Yukikazu Takeoka, and Toyoichi Tanaka

    Proc. Natl. Acad. Sci. USA   Vol. 97   page: 9861-9864   2000

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  233. Reversible molecular adsorption based on multiple-point interaction by shrinkable gels Reviewed

    T Oya, T Enoki, AY Grosberg, S Masamune, T Sakiyama, Y Takeoka, K Tanaka, GQ Wang, Y Yilmaz, MS Feld, R Dasari, T Tanaka

    SCIENCE   Vol. 286 ( 5444 ) page: 1543 - 1545   1999.11

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    A general approach is presented for creating polymer-gels that can recognize and capture a target molecule by multiple-point interaction and that can reversibly change their affinity to the target by more than one order of magnitude. The polymers consist of majority monomers that make the gel reversibly swell and shrink and minority monomers that constitute multiple-point adsorption centers for the target molecule, Multiple-point interaction is experimentally proven by power Laws found between the affinity and the concentration of the adsorbing monomers within the gels.

    Web of Science

  234. First order phase transition and evidence for frustrations in polyampholytic gels Reviewed

    Y Takeoka, AN Berker, R Du, T Enoki, A Grosberg, M Kardar, T Oya, K Tanaka, GQ Wang, XH Yu, T Tanaka

    PHYSICAL REVIEW LETTERS   Vol. 82 ( 24 ) page: 4863 - 4865   1999.6

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    Polyampholyte gel, frustrated by the conflicting interactions between its positive and negative monomers, c-an undergo a sharp discontinuous phase transition driven by changing either gel composition or solvent quality and/or permeability. This finding completes the investigation of all four major interactions involved in the biomolecular machinery with respect to their role in the behavior of polymer gels, considered here as a model of biopolymer system. The result also sheds light on the possible role of frustrations in biomolecular systems, such as proteins. [S0031-9007(99)09334-5].

    Web of Science

  235. First Order Phase Transition and Evidence for Frustrations in Polyampholyte Gels Reviewed

    Yukikazu Takeoka, A. Nihat Berker, Rose Du, Takashi Enoki, Alexander Grosberg, Mehran Kardar, Taro Oya, Kazunori Tanaka, Guoqiang Wang, Xiaohong Yu, Toyoichi Tanaka

    Phys. Rev. Lett.   Vol. 82   page: 4863-4865   1999

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  236. Reversible Molecular Adsorption Based on Multiple-Point Interaction by Shrinkable Gels Reviewed

    Taro Oya, Takashi Enoki, Alexander Yu. Grosberg, Satoru Masamune, Takaharu Sakiyama, Yukikazu Takeoka, Kazunori Tanaka, Guoqiang Wang, Yasar Yilmaz, Michael S. Feld, Ramachandra Dasari, and Toyoichi Tanaka

    Science   Vol. 286   page: 1543-1545   1999

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  237. Reversible molecular adsorption as a tool to observe freezing and to perform design of heteropolymer gels Reviewed

    T Tanaka, T Enoki, AY Grosberg, S Masamune, T Oya, Y Takaoka, K Tanaka, CN Wang, GQ Wang

    BERICHTE DER BUNSEN-GESELLSCHAFT-PHYSICAL CHEMISTRY CHEMICAL PHYSICS   Vol. 102 ( 11 ) page: 1529 - 1533   1998.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    Protein folding is one of the most challenging problems in science. How can polymers memorize and fold into unique conformations? How can they recognize molecules, catalyze chemical reactions, transfer molecular information, and create motions? The principle behind these mechanisms lies in the concept of thermodynamically stable phases of heteropolymers. Recent theories predict that the collapsed phase should be further classified into three phases: freely fluctuating like liquid, frozen in degenerate conformations, and frozen in a unique conformation. This yields a clue on how one can attempt creation artificial polymers capable to mimic some of the protein properties and functions. The reversible adsorption of target molecules is suggested as a primary means to achieve this goal. Target molecules with multiple adsorption sites play a twofold role. First, they mediate specific interactions between monomers and thus serve as "gluons". Second, monitoring the adsorption provides the experimental possibility to test directly on monomer contacts, which is directly related to observation of the order parameter associated with heteropolymer freezing transition. A slight change in the backbone conformation alters the spacial arrangement of the group, allowing for reversible adsorption and release. Polymer gels are developed that can reversibly change their affinity to target molecules by orders of magnitude. The gels are made of copolymers of backbone monomers that can reorganize themselves through thermal volume phase transition and of monomers that can attract the target at multiple contact points. Further the gels "imprinted" with the target showed a marked increase in the affinity, thus mimicing a protein-like ability to memorize and recognize certain target.

    Web of Science

  238. Reversible molecular adsorption as a tool to observe freezing and to perform design of heteropolymer gels Reviewed

    Tanaka, Toyoichi; Enoki, Takashi; Grosberg, Alexander Y.; Masamune, Satoru; Oya, Taro; Takaoka, Yukikazu; Tanaka, Kazunori; Wang, Changnan; Wang, Guoqiang.

    Ber. Bunsen-Ges.   Vol. 102 ( 11 ) page: 1529-1533   1998

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  239. Effect of supporting electrolyte concentration on the electrochemical reaction of redox-active surfactant micelles in aqueous solutions Reviewed

    Yukikazu Takeoka, Takashi Aoki, Kohei Sanui, Naoya Ogata, Masayoshi Watanabe

    Journal of Electroanalytical Chemistry   Vol. 438 ( 1-2 ) page: 153 - 158   1997.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier  

    The effect of NaCl concentration on the redox potential of α-ferrocenylundecyl-ω-hydroxy-polyoxyethylene (FPEG) micelles has been studied in aqueous solutions. With increasing NaCl concentration, the anodic half-wave potentials E1/2 of cyclic voltammograms of the aqueous solutions shift to higher potential, and the peak currents of the cyclic voltammograms decrease. The results are discussed in terms of thermodynamics of the micelle formation. An equation which interprets the correlation between the E1/2, the salt concentration, diffusion coefficient of the micelle DM, and the aggregation number m, has been derived. The changes in DM and m with NaCl concentration do not explain the change in the value of E1/2. The decrease in the equilibrium constant for the micelle-disruption Kd with increasing NaCl concentration affects the redox-potential of the FPEG micellar solutions. © 1997 Elsevier Science S.A.

    DOI: 10.1016/S0022-0728(97)00128-9

    Scopus

  240. Effect of supporting electrolyte concentration on the electrochemical reaction of redox-active surfactant micelles in aqueous solutions Reviewed

    Y Takeoka, T Aoki, K Sanui, N Ogata, R Watanabe

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   Vol. 438 ( 1-2 ) page: 153 - 158   1997.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE SA  

    The effect of NaCl concentration on the redox potential of alpha-ferrocenylundecyl-omega-hydroxy-polyoxyethylene (FPEG) micelles has been studied in aqueous solutions. With increasing NaCl concentration, the anodic half-wave potentials E-1/2 of cyclic voltammograms of the aqueous solutions shift to higher potential, and the peak currents of the cyclic voltammograms decrease. The results are discussed in terms of thermodynamics of the micelle formation. An equation which interprets the correlation between the E-1/2, the salt concentration, diffusion coefficient of the micelle D-M, and the aggregation number m, has been derived. The changes in D-M and m with NaCl concentration do not explain the change in the value of E-1/2. The decrease in the equilibrium constant for the micelle-disruption K-d with increasing NaCl concentration affects the redox-potential of the FPEG micellar solutions. (C) 1997 Elsevier Science S.A.

    Web of Science

  241. Cyclic voltammetric study of redox-active surfactant by hydrogel-modified electrode Reviewed

    Y Takeoka, T Aoki, K Sanui, N Ogata, M Watanabe

    POLYMER GELS AND NETWORKS   Vol. 5 ( 4 ) page: 369 - 383   1997

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    The dissolved states of redox-active non-ionic surfactant (FPEG) in the swollen state of N-isopropyl acrylamide (NIPA) hydrogel have been studied by using a gel-modified electrode. The pronounced decrease in the peak current and the negative shift in the formal potential of CV at the gel-modified electrode, as compared with the normal GC electrode, was observed in the micelle-solution; this indicates that the diffusive FPEG molecules which form the micelle hardly penetrate into the NIPA gel. This result suggests that there exists all interaction between FPEG molecules and the NIFA gel in the vicinity of the surface of the NIPA gel in the micelle-solution. However, this also indicates that a small amount of FPEG molecules which can form micelles exist in the NIPA gel. (C) 1997 Elsevier Science Ltd.

    Web of Science

  242. Cyclic voltammetric study of redox-active surfactant by gel-modified electrode Reviewed

    Yukikazu Takeoka, Takashi Aoki, Kohei Sanui, Naoya Ogata, Masayoshi Watanabe

    Polymer Gels and Networks   Vol. 5   page: 369-383   1997

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  243. Effect of supporting electrolyte concentration on the electrochemical reaction of redox-active surfactant micelles in aqueous solutions Reviewed

    Yukikazu Takeoka, Takashi Aoki, Kohei Sanui, Naoya Ogata, Masayoshi Watanabe

    J.Electroanal.Chem.   Vol. 438   page: 153-158   1997

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  244. Electrochemical studies of a redox-active surfactant. Correlation between electrochemical responses and dissolved states Reviewed

    Y Takeoka, T Aoki, K Sanui, N Ogata, M Watanabe

    LANGMUIR   Vol. 12 ( 2 ) page: 487 - 493   1996.1

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    Electrochemical studies of a nonionic surfactant, alpha-(ferrocenylundecyl)-omega-hydroxy-oligo(ethylene oxide) (FPEG), have been conducted in 0.16 M NaCl aqueous solution at a glassy carbon electrode. The correlation between electrochemical responses and dissolved states has been examined in detail. Cyclic voltammograms (upsilon = 10 mV/s) of the FPEG solutions change with the concentration; below the critical micelle concentration (cmc), the voltammetric shape is of a typical surface-confined species, while above the cmc the diffusion-controlled waves are superimposed at the cathodic side of the surface waves, and far above the cmc the voltammetric shape is of a typical diffusion-controlled species. FPEG in the aqueous solutions adsorbs onto the glassy carbon electrode surface to form a monolayer because of its surface activity. The adsorption isotherm has been represented by the Frumkin isotherm, which includes the repulsive interaction between the adsorbed FPEG molecules. Above the cmc, FPEG forms micelles. Chronoamperometrically determined apparent diffusion coefficients of the micellar solutions decrease with increasing concentrations. This has been interpreted in terms of the change in the diffusion species by disruption of the micelles into monomers at the cmc in the concentration gradient in diffusion layers. Cyclic voltammetric peak potentials of the micellar solutions shift toward the anodic side with the concentration. This behavior has been explained as the electrochemical reaction coupled with a preceding disassembled reaction of the micelles.

    Web of Science

  245. Electrochemical Studies of a Redox-active Surfactants. Correlation between Electrochemical Responses and Dissolved States Reviewed

    Yukikazu Takeoka, Takashi Aoki, Kohei Sanui, Naoya Ogata, Masayoshi Watanabe

    Langmuir   Vol. 12   page: 487-493   1996

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  246. RELATIONSHIPS BETWEEN VASCULAR BUNDLES OF PANICLE NECK INTERNODE AND CHARACTERS OF HEAD UNDER DIFFERENT PLANTING DENSITIES AND NITROGEN FERTILIZERS APPLIED IN ORYZA-SATIVA L

    HJ CUI, RZ JIN, Y TAKEOKA

    JAPANESE JOURNAL OF CROP SCIENCE   Vol. 64 ( 2 ) page: 216 - 220   1995.6

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    Investigations were carried out on the characters of rachilets, grains and grain weight per panicle of the growing rice plant cv. Shimokita under different planting density and nitrogen fertilizer norm conditions during the maturity stage of growth. The large vascular bundle (LVB), and small vascular bundle (SVB) of the panicle neck internode (PNI) and partial different internode were examined under a microscope. Analysing the above dare with various statistical methods, the change in LVB number of PNI and its relationship with rachilets, grains or grain weight were determined. The average numbers of LVB and SVB were 9.0 and 16.5, and the variable range were 5-13 and 11-22, respectively. The frequency distribution of these attributes in the Ist internode and itscoefficient variation was significantly larger that the other internodes. The number of LVB and SVB in PNI appeared to positively correlated; the former with the primary rachilets having a correlation coefficient (CC) of 0.894** and the latter with the secondary rachilets a CC of 0.764**. The LVB and SVB of the PNI exhibited a significantly higher positive correlation with the total grains at a CC of 0.955** and 0.850**, respectively. The number of LVB and SVB of the PNI increased with increasing nitrogen fertilizer norm. The number of LVB and SVB of the PNI decreased with increasing planting densities.

    DOI: 10.1626/jcs.64.216

    Web of Science

    Scopus

  247. ELECTROCHEMICAL CONTROL OF DRUG-RELEASE FROM REDOX-ACTIVE MICELLES Reviewed

    Y TAKEOKA, T AOKI, K SANUI, N OGATA, M YOKOYAMA, T OKANO, Y SAKURAI, M WATANABE

    JOURNAL OF CONTROLLED RELEASE   Vol. 33 ( 1 ) page: 79 - 87   1995.1

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    Electrochemical control of drug release was demonstrated by redox-active micelles of non-ionic surfactants having a ferrocenyl moiety (FPEG). The surfactants formed micelles at the concentrations above the critical micelle concentration (CMC = 0.1 mM) in normal saline solutions when they existed as the reduced form (FPEG), whereas the micelles were disassembled into monomers when they existed as the oxidized form (FPEG(+)). This change was reversible and electrochemically controlled. The electroactivity of FPEG determined by cyclic voltammetry was quite sensitive to the aggregation states. Perylene, which was used as a model of hydrophobic drugs, could be solubilized in a 2 mM FPEG normal saline solution, however, it was hardly solubilized in a 2 mM FPEG(+) solution that was made by oxidation of the former solution. Quick and discrete response for releasing perylene from the redox active micelles was achieved by using controlled potential bulk electrolysis method.

    Web of Science

  248. INTERACTION BETWEEN REDOX-ACTIVE NON IONIC SURFACTANT MICELLE AND POLY(ACRYLIC ACID) Reviewed

    Y TAKEOKA, T AOKI, K SANUI, N OGATA, M WATANABE

    KOBUNSHI RONBUNSHU   Vol. 52 ( 10 ) page: 657 - 661   1995

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:SOC POLYMER SCIENCE JAPAN  

    A non-ionic redox active surfactant, alpha-ferrocenylundecyl-omega-hydroxy-oligo(ethylene oxide), exhibits high ability to form polymer complexes with poly(acrylic acid) at a micelle forming concentration, in spite of the low molecular weight of the oligo(ethylene oxide) site. The fraction of carboxyls associated with ether oxygens (theta) between them has a high value (ca. 0.8) which is independent of the concentration of poly(acrylic acid). The complex formation seemed to be caused by hydrogen bonding and hydrophobic interactions. The complex formation influenced on electrochemical reactions of the redox active surfactant.

    Web of Science

  249. Electrochemical control of drug release from redox-active micelles Reviewed

    Yukikazu Takeoka, Takashi Aoki, Kohei Sanui, Naoya Ogata, Masayuki Yokoyama, Teruo Okano, Yasuhisa Sakurai, Masayoshi Watanabe

    J. Controlled Release   Vol. 33   page: 79-87   1995

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  250. Interaction between redox-active non-ionic surfactant micelle and poly(acrylic acid) Reviewed

    Yukikazu Takeoka, Takashi Aoki, Kohei Sanui, Naoya Ogata, Masayoshi Watanabe

    Kobunsi Ronbunshu   Vol. 52   page: 642-647   1995

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Books 58

  1. 自己組織化マテリアルのフロンティア : 次代を担う研究者による提案 : 未来を創るエキゾチック自己組織化戦略

    「エキゾチック自己組織化材料」研究グループ, 中西 尚志, 松浦 和則, 矢貝 史樹, 角五 彰, 岸村 顕広, 佐伯 昭紀, 竹岡 敬和, 内藤 昌信, 舟橋 正浩( Role: Sole author)

    フロンティア出版  2015  ( ISBN:9784902410266

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    Language:Japanese

    CiNii Books

  2. 有機機能材料 : 基礎から応用まで

    松浦 和則, 角五 彰, 岸村 顕広, 佐伯 昭紀, 竹岡 敬和, 内藤 昌信, 中西 尚志, 舟橋 正浩, 矢貝 史樹( Role: Sole author)

    講談社  2014  ( ISBN:9784061568020

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    Language:Japanese

    CiNii Books

  3. Applications of Stimuli-Sensitive Inverse Opal Gels

    Takeoka, Y( Role: Sole author)

    RSC Publishing  2013.1 

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    Responsible for pages:150-189   Language:Japanese

  4. Applications of Stimuli-Sensitive Inverse Opal Gels

    Takeoka, Y.( Role: Sole author)

    RSC Publishing  2013.1 

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    Language:Japanese

  5. アクチュエータ〜研究開発の最前線

    竹岡 敬和( Role: Sole author)

    NTS  2011 

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    Responsible for pages:498-503   Language:Japanese

  6. アクチュエータ〜研究開発の最前線

    竹岡 敬和( Role: Sole author)

    2011 

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    Language:Japanese

  7. 構造発色性ゲル

    ( Role: Sole author)

    2010 

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    Responsible for pages:?   Language:Japanese

  8. 論文にみる最重要概念と革新実験データ

    ( Role: Sole author)

    2010 

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    Responsible for pages:??   Language:Japanese

  9. 論文にみる最重要概念と革新実験データ

    ( Role: Sole author)

    2010 

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  10. 構造発色性ゲル

    ( Role: Sole author)

    2010 

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    Language:Japanese

  11. “コロイド微粒子が形成する集合状態と構造発色性材料への応用”日本結晶成長学会誌

    竹岡 敬和( Role: Sole author)

    2009 

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    Responsible for pages:49-54   Language:Japanese

  12. 非侵襲的血糖値測定~構造色ゲルを利用したグルコースセンサー~”バイオ健康&医療用デバイス

    竹岡 敬和( Role: Sole author)

    シーエムシー出版  2009 

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    Responsible for pages:168-175   Language:Japanese

  13. 呈色・変色ゲル

    竹岡 敬和( Role: Sole author)

    超分子サイエンス&テクノロジー~基礎からイノベーションまで~、NTS  2009 

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    Responsible for pages:689-693   Language:Japanese

  14. コロイドアモルファスアレイが示す角度依存性のない構造性発色

    竹岡敬和( Role: Sole author)

    2009 

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    Responsible for pages:20-29   Language:Japanese

  15. ゲル コントロール~ゲルの上手な作り方とゲル化の抑制~

    竹岡 敬和( Role: Sole author)

    情報機構  2009 

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    Responsible for pages:615-626   Language:Japanese

  16. 呈色・変色ゲル

    竹岡 敬和( Role: Sole author)

    超分子サイエンス&テクノロジー~基礎からイノベーションまで~、NTS  2009 

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    Language:Japanese

  17. コロイドアモルファスアレイが示す角度依存性のない構造性発色

    竹岡敬和( Role: Sole author)

    2009 

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    Language:Japanese

  18. ゲル コントロール~ゲルの上手な作り方とゲル化の抑制~

    竹岡 敬和( Role: Sole author)

    情報機構  2009 

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    Language:Japanese

  19. “コロイド微粒子が形成する集合状態と構造発色性材料への応用”日本結晶成長学会誌

    竹岡 敬和( Role: Sole author)

    2009 

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    Language:Japanese

  20. 非侵襲的血糖値測定~構造色ゲルを利用したグルコースセンサー~”バイオ健康&医療用デバイス

    竹岡 敬和( Role: Sole author)

    シーエムシー出版  2009 

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    Language:Japanese

  21. “ コロイド結晶を利用した構造色センサー”ナノ粒子の創製と応用展開

    本多正樹, 竹岡敬和, 関隆広( Role: Joint author)

    フロンティア出版  2008 

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    Responsible for pages:140-148   Language:Japanese

  22. “高分子ゲルの階層的構造制御による機能化”ゲル・イノベーション、ポリマーフロンティア21シリーズ、高分子学会編

    竹岡 敬和( Role: Sole author)

    NTS  2008 

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    Responsible for pages:121-167   Language:Japanese

  23. “構造色ゲルを利用したグルコースセンサーへの展開”医療用ゲルの最新技術と開発ーバイオミメティックゲルの応用

    竹岡 敬和( Role: Sole author)

    シーエムシー出版  2008 

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    Responsible for pages:115-124   Language:Japanese

  24. “構造色を示すソフトマテリアル”「光と界面がおりなす新しい化学の世界」講演収録集

    竹岡 敬和( Role: Sole author)

    クバプロ  2008 

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    Responsible for pages:115-120   Language:Japanese

  25. “呈色・変色ゲル”超分子サイエンス~基礎から材料への展開~

    竹岡 敬和( Role: Sole author)

    NTS  2008 

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    Language:Japanese

  26. “フォトクロミック色素を導入したポーラスゲル”多孔体の精密制御と機能・物性評価

    竹岡 敬和( Role: Sole author)

    サイエンス&テクノロジー  2008 

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    Responsible for pages:442-447   Language:Japanese

  27. “呈色・変色ゲル”超分子サイエンス~基礎から材料への展開~

    竹岡 敬和( Role: Sole author)

    NTS  2008 

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    Language:Japanese

  28. “フォトクロミック色素を導入したポーラスゲル”多孔体の精密制御と機能・物性評価

    竹岡 敬和( Role: Sole author)

    サイエンス&テクノロジー  2008 

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  29. “高分子ゲルの階層的構造制御による機能化”ゲル・イノベーション、ポリマーフロンティア21シリーズ、高分子学会編

    竹岡 敬和( Role: Sole author)

    NTS  2008 

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    Language:Japanese

  30. “構造色を示すソフトマテリアル”「光と界面がおりなす新しい化学の世界」講演収録集

    竹岡 敬和( Role: Sole author)

    クバプロ  2008 

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    Language:Japanese

  31. “構造色ゲルを利用したグルコースセンサーへの展開”医療用ゲルの最新技術と開発ーバイオミメティックゲルの応用

    竹岡 敬和( Role: Sole author)

    シーエムシー出版  2008 

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    Language:Japanese

  32. “ コロイド結晶を利用した構造色センサー”ナノ粒子の創製と応用展開

    本多正樹、竹岡敬和、関隆広( Role: Joint author)

    フロンティア出版  2008 

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    Language:Japanese

  33. 2.2 構造(形)-機能相関の科学”自然に学ぶ材料プロセッシング

    竹岡敬和( Role: Joint author)

    三共出版  2007 

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    Responsible for pages:81-90   Language:Japanese

  34. “フォトクロミックゲル”光化学協会誌

    竹岡敬和( Role: Sole author)

    2007 

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    Responsible for pages:126-129   Language:Japanese

  35. “ゲルの体積相転移”高分子高分子

    永山國昭, 竹岡敬和( Role: Joint author)

    2007 

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    Responsible for pages:26-27   Language:Japanese

  36. “Structural Colored Gel”in “Bottom-up Nanofabrication: Supramolecules, Self-Assemblies, and Organized Films”

    Takeoka, Y( Role: Sole author)

    American Scientific Publisheres  2007 

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    Responsible for pages:XX   Language:English

  37. “フォトクロミックゲル”光化学協会誌

    竹岡敬和( Role: Sole author)

    2007 

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    Language:Japanese

  38. “Structural Colored Gel”in “Bottom-up Nanofabrication: Supramolecules, Self-Assemblies, and Organized Films”

    Takeoka, Y.( Role: Sole author)

    American Scientific Publisheres  2007 

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    Language:English

  39. 2.2 構造(形)-機能相関の科学”自然に学ぶ材料プロセッシング

    竹岡敬和( Role: Joint author)

    三共出版  2007 

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    Language:Japanese

  40. “ゲルの体積相転移”高分子高分子

    永山國昭、竹岡敬和( Role: Joint author)

    2007 

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  41. “ゲルを用いて光を操る-構造色ゲル”

    竹岡敬和( Role: Sole author)

    機能材料  2006 

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    Responsible for pages:31-42   Language:Japanese

  42. “構造色を示すゲルによる高分子鎖の振る舞いの観察”

    竹岡 敬和( Role: Sole author)

    膜  2006 

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    Responsible for pages:296-301   Language:Japanese

  43. “コロイド結晶をテンプレートとした構造色ゲルの作成とセンサーデバイスへの応用”ナノ微粒子合成とフォトニクスへの展開、ポリマーフロンティア21シリーズ、高分子学会編

    竹岡 敬和( Role: Sole author)

    NTS  2006 

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    Responsible for pages:93-132   Language:Japanese

  44. “ゲルを用いて光を操る-構造色ゲル”

    竹岡敬和( Role: Sole author)

    機能材料  2006 

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    Language:Japanese

  45. “コロイド結晶をテンプレートとした構造色ゲルの作成とセンサーデバイスへの応用”ナノ微粒子合成とフォトニクスへの展開、ポリマーフロンティア21シリーズ、高分子学会編

    竹岡 敬和( Role: Sole author)

    NTS  2006 

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    Language:Japanese

  46. “構造色を示すゲルによる高分子鎖の振る舞いの観察”

    竹岡 敬和( Role: Sole author)

    膜  2006 

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  47. “クロミックゲル”、新規クロミック材料の最新技術

    竹岡 敬和( Role: Sole author)

    シーエムシー出版  2005 

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    Responsible for pages:101-110   Language:Japanese

  48. “構造色ゲル ”

    竹岡 敬和( Role: Sole author)

    高分子  2005 

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    Responsible for pages:258-263   Language:Japanese

  49. “構造色を示すゲル~鋳型を用いたゲルの機能化~”現代化学

    竹岡 敬和( Role: Sole author)

    東京化学同人  2005 

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    Responsible for pages:24-31   Language:Japanese

  50. “光で光を操るやわらかい材料”図解高分子新素材のすべて

    竹岡 敬和( Role: Sole author)

    工業調査会  2005 

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    Responsible for pages:42-45   Language:Japanese

  51. “構造色を示すゲル~鋳型を用いたゲルの機能化~”現代化学

    竹岡 敬和( Role: Sole author)

    東京化学同人  2005 

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    Language:Japanese

  52. “光で光を操るやわらかい材料”図解高分子新素材のすべて

    竹岡 敬和( Role: Sole author)

    工業調査会  2005 

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    Language:Japanese

  53. “クロミックゲル”、新規クロミック材料の最新技術

    竹岡 敬和( Role: Sole author)

    シーエムシー出版  2005 

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    Language:Japanese

  54. “構造色ゲル ”

    竹岡 敬和( Role: Sole author)

    高分子  2005 

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    Language:Japanese

  55. “ソフトマテリアルによる構造の記憶と機能の発現”ソフトマテリアルの新展開

    竹岡敬和( Role: Sole author)

    シーエムシー出版  2004 

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    Responsible for pages:112-132   Language:Japanese

  56. “光学・構造色ゲル”高分子ゲルの最新動向

    竹岡敬和( Role: Sole author)

    シーエムシー出版  2004 

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    Responsible for pages:227-241   Language:Japanese

  57. “光学・構造色ゲル”高分子ゲルの最新動向

    竹岡敬和( Role: Sole author)

    シーエムシー出版  2004 

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    Language:Japanese

  58. “ソフトマテリアルによる構造の記憶と機能の発現”ソフトマテリアルの新展開

    竹岡敬和( Role: Sole author)

    シーエムシー出版  2004 

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    Language:Japanese

▼display all

MISC 2

  1. Stimuli-sensitive Phase-Separated Color Material using Christiansen Filter Effect

      Vol. 33 ( 5 ) page: 32 - 37   2013.5

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    Language:Japanese  

    CiNii Books

  2. Design of Soft Materials from Colloidal Crystals

    TAKEOKA YUKIKAZU, WATANABE MASAYOSHI

    Fiber   Vol. 59 ( 2 ) page: "P - 49"-"P-54"   2003.2

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    Language:Japanese  

    CiNii Books

Presentations 32

  1. Fabrication of mono-dispersed spherical assemblies and these structural colors by using microflow device

    Teshima M.

    Proceedings of the 16th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2012 

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    Event date: 2012

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  2. Selective surface modification of PNIPA gel surface by imprinting method

    Ueda A.

    Polymer Preprints, Japan 

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    Event date: 2006.12

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  3. Preparation and optical properties of ordered arrays of glucose-responsible submicrogel particles trapped in inverse opal polystyrene

    Honda M.

    Polymer Preprints, Japan 

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    Event date: 2006.12

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  4. Photomechanical effect of azobenzene liquid crystalline gel impregnated with low molecular weight liquid crystals

    Hayata Y.

    Polymer Preprints, Japan 

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    Event date: 2006.12

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  5. Design of novel microactuator made of self-oscillating gel by assembling the microbeads and controlling their crosslinking structures

    Sakai T.

    Polymer Preprints, Japan 

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    Event date: 2006.12

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  6. Patterning of NIPA gel surface by surface imprinting method

    Ueda A.

    Polymer Preprints, Japan 

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    Event date: 2006.10

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  7. Preparation of crosslinked azobenzene liquid crystalline polymer films and their direct evaluation by UV-Vis absorption spectrum

    Hayata Y.

    Polymer Preprints, Japan 

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    Event date: 2006.10

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  8. Preparation and optical properties of ordered arrays of glucose-responsible nanogel particles trapped in inverse opal polystyrene

    Honda M.

    Polymer Preprints, Japan 

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    Event date: 2006.10

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  9. Swelling behavior of polyrotaxane gels exhibiting structural colors

    Murayama H.

    Polymer Preprints, Japan 

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    Event date: 2006.10

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  10. Design of functional surface by arraying self-oscillationg nano-gel beads

    Sakai T.

    Polymer Preprints, Japan 

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    Event date: 2006.10

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  11. Proposal of multicolor electrochromic polymer gels

    Ueno K.

    Polymer Preprints, Japan 

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    Event date: 2005.12

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  12. Photo-control of spatio-temporal oscillation in a gel system with light-sensitive Belousov-Zhabotinsky reaction

    Shinohara S.

    Polymer Preprints, Japan 

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    Event date: 2005.12

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  13. Structural colored gel

    Takeoka Y.

    Polymer Preprints, Japan 

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    Event date: 2005.12

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  14. Surface modification of gel by molecularly imprinting method

    Ueda A.

    Polymer Preprints, Japan 

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    Event date: 2005.12

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  15. Synthesis of photo-responsive porous poly(NIPA) gel and evaluation of its optical properties

    Matsubara K.

    Polymer Preprints, Japan 

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    Event date: 2005.12

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  16. Design of nano-oscillation using self-oscillating polymer and the analysis of cooperative effects

    Sakai T.

    Polymer Preprints, Japan 

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    Event date: 2005.12

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  17. Electrically induced structural color change in periodically ordered porous gels having ionized groups

    Ueno K.

    Polymer Preprints, Japan 

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    Event date: 2005.12

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  18. Design of functional surface by arraying self-oscillationg nano-gel beads International conference

    Sakai T

    Polymer Preprints, Japan  2006.10.19 

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    Language:English   Presentation type:Oral presentation (general)  

  19. Synthesis of photo-responsive porous poly(NIPA) gel and evaluation of its optical properties International conference

    Matsubara K

    Polymer Preprints, Japan  2005.12 

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    Language:English   Presentation type:Oral presentation (general)  

  20. Swelling behavior of polyrotaxane gels exhibiting structural colors International conference

    Murayama H

    Polymer Preprints, Japan  2006.10.19 

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    Language:English   Presentation type:Oral presentation (general)  

  21. Surface modification of gel by molecularly imprinting method International conference

    Ueda A

    Polymer Preprints, Japan  2005.12 

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    Language:English   Presentation type:Oral presentation (general)  

  22. Structural colored gel International conference

    Takeoka Y

    Polymer Preprints, Japan  2005.12 

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    Language:English   Presentation type:Oral presentation (general)  

  23. Selective surface modification of PNIPA gel surface by imprinting method International conference

    Ueda A

    Polymer Preprints, Japan  2006.12 

     More details

    Language:English   Presentation type:Oral presentation (general)  

  24. Proposal of multicolor electrochromic polymer gels International conference

    Ueno K

    Polymer Preprints, Japan  2005.12 

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    Language:English   Presentation type:Oral presentation (general)  

  25. Preparation of crosslinked azobenzene liquid crystalline polymer films and their direct evaluation by UV-Vis absorption spectrum International conference

    Hayata Y

    Polymer Preprints, Japan  2006.10.19 

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    Language:English   Presentation type:Oral presentation (general)  

  26. Preparation and optical properties of ordered arrays of glucose-responsible submicrogel particles trapped in inverse opal polystyrene International conference

    Honda M

    Polymer Preprints, Japan  2006.12 

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    Language:English   Presentation type:Oral presentation (general)  

  27. Preparation and optical properties of ordered arrays of glucose-responsible nanogel particles trapped in inverse opal polystyrene International conference

    Honda M

    Polymer Preprints, Japan  2006.10.19 

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    Language:English   Presentation type:Oral presentation (general)  

  28. Photomechanical effect of azobenzene liquid crystalline gel impregnated with low molecular weight liquid crystals International conference

    Hayata Y

    Polymer Preprints, Japan  2006.12 

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    Language:English   Presentation type:Oral presentation (general)  

  29. Photo-control of spatio-temporal oscillation in a gel system with light-sensitive Belousov-Zhabotinsky reaction International conference

    Shinohara S

    Polymer Preprints, Japan  2005.12 

     More details

    Language:English   Presentation type:Oral presentation (general)  

  30. Patterning of NIPA gel surface by surface imprinting method International conference

    Ueda A

    Polymer Preprints, Japan  2006.10.19 

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    Language:English   Presentation type:Oral presentation (general)  

  31. Electrically induced structural color change in periodically ordered porous gels having ionized groups International conference

    Ueno K

    Polymer Preprints, Japan  2005.12 

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    Language:English   Presentation type:Oral presentation (general)  

  32. Fabrication of mono-dispersed spherical assemblies and these structural colors by using microflow device International conference

    Teshima M

    Proceedings of the 16th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2012  2012 

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    Language:English   Presentation type:Oral presentation (general)  

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Research Project for Joint Research, Competitive Funding, etc. 12

  1. 分子結合制御の新手法開発プロジェクト

    2015.4 - 2019

    ImPACT 

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    Grant type:Competitive

  2. “環境応答型メタマテリアル”の創成

    2010

    (財)村田学術振興財団 

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    Grant type:Competitive

  3. 角度依存性のない構造色発現機能を示すコロイドアモルファスの構築とその応用

    2010

    日本板硝子材料工学助成会 

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    Grant type:Competitive

  4. コロイド準結晶を利用した新規光学材料の創製

    2010

    (財)東海産業技術振興財団 

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    Grant type:Competitive

  5. 準周期性構造を有する角度依存性のないフォトニックバンドギャップを示す材料の創製

    2009.8

    財団法人 立松財団 

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    Grant type:Competitive

  6. 準周期性構造を有する角度依存性のないフォトニックバンドギャップを示す材料の創製

    2009.4

    (財)池谷科学技術振興財団 

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    Grant type:Competitive

  7. モルフォ蝶などの生物に学ぶ角度依存性のないフォトニックバンドを           示すアクティブフォトニック結晶の創製

    2009.1 - 2012.12

  8. コロイド準結晶を利用した角度依存性のない構造色を示す光学材料の創製

    2008.9

    積水化学 自然に学ぶものづくり 研究助成プログラム 

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    Grant type:Competitive

  9. 角度依存性のない構造色を示すソフトフォトニック結晶の構築

    2008.4

    学内共同研究 

  10. 新規アクティブフォトニック結晶の創製

    2008

    徳 山 科 学 技 術 振 興 財 団 

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    Grant type:Competitive

  11. 光学材料および医療材料に適用可能な高機能性ソフトマテリアルに関する研究

    2007 - 2008

    小笠原科学技術振興財団 

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    Grant type:Competitive

  12. 非観血性装着型簡易グルコースセンサーの開発

    2006

    稲盛財団 

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    Grant type:Competitive

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KAKENHI (Grants-in-Aid for Scientific Research) 22

  1. Development of Coating Process of Structural Color by Electrophoretic Deposition of Mixed Dispersion of White and Black Particles

    Grant number:16K14388  2016.4 - 2018.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research  Grant-in-Aid for Challenging Exploratory Research

    KATAGIRI Kiyofumi, TAKEOKA Yukikazu

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    Authorship:Collaborating Investigator(s) (not designated on Grant-in-Aid) 

    Grant amount:\3640000 ( Direct Cost: \2800000 、 Indirect Cost:\840000 )

    In this study, a novel approach for creating structural color coatings from monodisperse SiO2 particles is presented. The structural color coating films, formed from an array of SiO2 particles with a small amount of black additive, are easily prepared by an electrophoretic deposition (EPD) technique. Structural color coatings on materials with curved surfaces and complicated shapes are also achieved by the EPD method. A cathodic EPD is much favor since metal ions elute from anodes. Therefore, structurally colored coating films were prepared by the cathodic EPD method using monodispersed SiO2 particles, CB and polycations. The arrangement of the particle array is also controlled by pH condition of cathodic EPD. The iridescence, i.e., the angular dependence, of the structural color dramatically changes with the arrangement of the particle array.

  2. 角膜から学ぶ光学的および力学的に高機能な材料の開発

    2015.4 - 2018.3

    科学研究費補助金  基盤研究(A)

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    Authorship:Principal investigator 

  3. Development of optically and mechanically highly functional materials to learn from the cornea

    Grant number:15H02200  2015.4 - 2018.3

    Takeoka Yukikazu

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    Authorship:Principal investigator 

    Grant amount:\43030000 ( Direct Cost: \33100000 、 Indirect Cost:\9930000 )

    In this study, we tried to prepare the transparent composite material where fine silica particles form aggregation with short-range order, and transparent flexible polymer gel fills the interstices between the particles. When the concentration of the fine silica particles to the polymer gel is lower than 15 vol%, the randomly-arranged fine silica particles induced incoherent scattering. Consequently, the composite material becomes cloudy. With increasing the concentration of the fine silica particles, however, the transparence of the composite material becomes higher because of the order formation of the fine silica particles. The order distance and the structure of the fine silica particles can be controlled by adjusting these concentration. Moreover, we found that the transparent composite material has also high mechanical strength which combines flexibility of the gel and high elasticity of the silica fine particles.

  4. Functonalization of Structurally Colored Materials based on Amorphous Array of Colloidal Particles

    Grant number:26630320  2014.4 - 2016.3

    KATAGIRI Kiyofumi

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    Authorship:Coinvestigator(s) 

    Recently, development of colored pigments with low-toxicity and minimal environmental impact attracts much attention. Structural color of colloidal crystals is one of the most versatile candidates. However, structural color of colloidal crystals has angle-dependence and restrictions for coating. In this study, angle-independent structural color materials based on amorphous array of colloidal particles were investigated. Firstly, SiO2-TiO2 monodispersed particles were developed for achievement of photochromism of structural color materials. Secondly, structural color coatings were prepared by an electrophoretic deposition (EPD) method using monodispersed SiO2 particles and carbon black nanoparticles. Influences of applied voltage and deposition time of EPD on the thickness and array structure of coating films were investigated in detail.

  5. Mesoscopically Sized and Restricted PolymerThin Films for Creation of New Photoresponsive Functions

    Grant number:23225003  2011.4 - 2016.3

    Seki Takahiro

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    Authorship:Coinvestigator(s) 

    The photoalignment technology was initiated approximately 30 years ago, and now has become a significant tool in industry to fabricate liquid crystal display devices. However, many fundamental issues still need to be elucidated. This project dealt with the photoalighment behavior in systems containing mesoscopic structures, in restricted sized films, and further non-plane surface systems. Herein, we attempted to elucidate the mechanism in the photoalighment process of microphase separation structures in block copolymer films, phase separation structure of blended polymers in small sized state obtained by inkjet printing, and proposed the photoresponsive surface wrinkle systems. Through these approaches, deeper understandings on the photoalignment processes were obtained, and new procedures were proposed. In particular, we originally proposed the photoalignment processes based on the manipulation of the free surface of liquid crystal polymer films.

  6. Simple Preparation and Optical Properties of Colloidal Amorphous Array

    Grant number:23245047  2011.4 - 2014.3

    TAKEOKA Yukikazu

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    Authorship:Principal investigator 

    Grant amount:\49790000 ( Direct Cost: \38300000 、 Indirect Cost:\11490000 )

    There are many industrial applications for coloured pigments that have anti-fading properties. Developing a low-cost, high-volume production method for anti-fading pigments that have low toxicity and minimal environmental impact may support their widespread use. To accomplish this goal, we need to prepare pigments using abundant and environmentally friendly chemical compounds. We demonstrated that the aggregation of fine, submicron silica spherical particles produces various colours. Because the microstructure of this aggregation is isotropic and has short-range order on a length scale comparable to optical wavelengths, angle-independent structural colour caused by wavelength-specific constructive reflection is exhibited. The saturation of colour from this aggregation can be increased by adding a small amount of a conventional black particle. Colourful green pigments can be prepared by combining different sizes of fine submicron silica spherical particles with black particle.

  7. 有機ゲルおよび高分子を用いる融合マテリアルの動的機能の開拓

    2010.6 - 2015.3

    科学研究費補助金  新学術領域研究

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    Authorship:Principal investigator 

  8. Comprehensive Research on Fusion Materials: Creative Development of Materials and Exploration of Their Function through Molecular Control

    Grant number:22107001  2010.4 - 2016.3

    Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

    KATO Takashi

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    Authorship:Coinvestigator(s) 

  9. Exploration of Dynamic Functions of Fusion Materials using Organic Hydrogels and Polymers

    Grant number:22107012  2010.4 - 2015.3

    Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

    TAKEOKA YUKIKAZU

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    Authorship:Principal investigator 

    Grant amount:\57720000 ( Direct Cost: \44400000 、 Indirect Cost:\13320000 )

    Our recent advances in the preparation of fusion materials between many types of submicrometer-sized fine inorganic particles and stimuli-sensitive soft materials such as gels have introduced exciting new possibilities for developing unprecedented new materials with optical and mechanical properties. In this study, stimuli-responsive colloidal amorphous arrays displaying various angle-independent structural colors which are one these interesting new materials were studied. Similarly to humans yearning to fly like birds and eventually developing airplanes, we may be able to develop new fusion materials for optical applications; such materials may be beyond what can be synthesized in natural systems and may someday be useful for enhancing our quality of life. We look forward to the development of materials with similar exciting functions stemming from future advances in the field of materials science.

  10. Fabrication of Soft Photonic Crystal exhibiting Angle-independent Structural Color

    Grant number:20350105  2008 - 2010

    TAKEOKA Yukikazu

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    Authorship:Principal investigator 

    Grant amount:\18590000 ( Direct Cost: \14300000 、 Indirect Cost:\4290000 )

    We have demonstrated for the first time that an amorphous arrays of colloidal particles displays structural color with low-angle-dependence. This finding is in contrast to the common understanding that a periodic dielectric structure is fundamental to Photonic Band Gap production. It is worth noting that the reported material with such an optical phenomenon could serve as a means to overcome the technological barrier where angle-dependent structural color becomes a major issue, for example, in full color displays with wide viewing angles.

  11. Photomechanical responses in two-dimensional self-assembled systems and their applications

    Grant number:19050005  2007 - 2010

    SEKI Takahiro

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    Authorship:Coinvestigator(s) 

    Photomechanical effects are now widely studied in photochromic materials. This work deals with two-dimensional photomechanical systems that should be of great value to elucidate precise mechanisms at molecular levels. The work composed of three projects. 1) Photoresponsive block copolymers are spread on water and photoinduced morphological changes of two-dimensional microphase separation (MPS) structures are observed. 2) In liquid crystalline (LC) thin films of block copolymers, the orientation of MPS mesostructures are photoaligned and reoriented. The real time observations are feasible by use of an X-ray beam from a synchrotron radiation facility. 3) The precise understandings of transfer motions of LC azobenzene polymers thin films are obtained, and this phenomenon is applied to process inorganic materials.

  12. Creation of polymer thin films possessing unique molecular orientations and photoresponsive properties

    Grant number:19350056  2007 - 2009

    SEKI Takahiro

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    Authorship:Coinvestigator(s) 

    Liquid crystalline (LC) polymer brushes containing an azobenzene (Az) mesogenic moiety on a quartz or silicon substrate are prepared by surface initiated atom transfer radical polymerization (ATRP). The grafted chain film adopted a smectec LC phase and the molecular orientation of Az mesogens in the grafted chain was parallel to the substrate plane. Highly ordered in-plane photoalignment of Az mesogens in the grafted chain was readily provided by the irradiation with linearly polarized visible light due to the effective light absorption of the Az mesogens aligned parallel to the substrate.

  13. 周期構造を有するゲルの特異的光反射挙動の解明と新規フォトニックデバイスの構築

    Grant number:17685023  2005 - 2007

    竹岡 敬和

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    Authorship:Principal investigator 

    Grant amount:\29120000 ( Direct Cost: \22400000 、 Indirect Cost:\6720000 )

    申請者は、"構造刷り込み法"を利用したゲルの調製により、従来に見られない性質や機能をゲルに導入することに取り組んできた。その結果、1)構造色を発現するゲルの構築手法の確立、および、2)構造色変化から分子レベルの挙動を解析する手法の開発、という二つの成果が得られた。各年度で行った研究内容を以下に示す。
    平成17年度
    与えられた環境で望みの構造色を示す構造発色性ゲルの調製が可能となった。
    平成18年度
    特定の物質の添加に応じて色が変わるセンサーとしての利用の道を切り開いた。
    平成19年度
    光の照射、電場の印可などによって色が変わるディスプレイ用デバイスとしての利用を検討した。
    今後は、このようなモルフォ蝶の翅の構造発色性を参考にして、角度依存性のない構造発色性ゲルを構築する手法を開発する。この研究により、"構造色は光の波長オーダーの周期的な構造によって生じており、構造色は角度依存性があるもの"だという従来のイメージを払拭し、不規則性や色素の導入などの新たな効果を施すことで、"構造色にも多様性がある"ことを具現化できると考えている。さらに、このような構造色の多様性を、我々がこれまでに研究してきた環境応答型構造発色性ゲルに付与すれば、全反射型のディスプレイや簡易型センサーなど、光学デバイス開発へと展開できる。

  14. ソフトマテリアルを用いた自律応答型アクチュエーターの開発

    Grant number:17040019  2005 - 2006

    竹岡 敬和

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    Authorship:Principal investigator 

    Grant amount:\6100000 ( Direct Cost: \6100000 )

    本研究では、シリカコロイド結晶を鋳型に用いて得られる構造色を示すゲルにルテニウム錯体を導入したゲルを調製し、BZ反応という非線形化学反応に連動して蠕動運動するソフトマテリアルの周期や蠕動運動時の膜厚変化を分光学的に調査できるシステムの開発に取り組んできた。最近の研究結果から、BZ反応に連動して蠕動運動をしているゲルに特定の波長の光を照射すると、その光量に応じて蠕動運動の振幅や周期が変化することが分かった。また、光の照射形状によって、蠕動運動のする部分め形状や蠕動運動の方向も制御できることが分かってきた。
    平成17年度
    BZ反応という非線形化学反応に連動して蠕動運動するソフトマテリアルの開発に成功した。また、本ソフトマテリアルは温度変化に応じて、その蠕動運動の周期を変化させることがわかった。
    本内容は、Nature Materials誌の紹介記事に取り上げられた。
    平成18年度
    平成17年度までに開発した"BZ反応に連動して蠕動運動するソフトマテリアル"の動きを光の照射によって、その周期性、運動の方向、運動部位などを制御することに成功した。精置状況下では、ランダムな動きを示すBZ反応に連動したゲルの動きを、BZ反応の触媒として働くルテニウム錯体が強く吸収する光(450nm)を照射することで、その反応の抑制とともに、ゲルの動きにも影響を与えられることを明らかにした。本ゲルは、BZ反応以外の非線形化学反応とも連動した系を調製できるのでその応用範囲は広い。

  15. フォトニックバンドギャップを有するソフトマテリアルの構築とそのセンサーデバイスへ

    Grant number:17029031  2005 - 2006

    竹岡 敬和

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    Authorship:Principal investigator 

    Grant amount:\2800000 ( Direct Cost: \2800000 )

    従来の研究では、ゲルの長さを測定することで、網目を構成する高分子鎖の拡がり具合を評価できることがわかっていた。本研究では、コロイド結晶を鋳型に用いて構造色を示すポーラスゲルを作ることで、光の波長ほどの周期で屈折率が変化する構造をゲル内に導入すると、分子レベルの挙動を色の変化として観測できるようになることを明らかにした。本研究において確立した構造色を示すゲルを作る方法は、光応答性ゲル、電場応答性ゲル、分子認識ゲルなど、様々なゲルに対して適用することができる。光応答性を示す性質を付与した構造色ゲルは、光の照射に伴って構造色の二状態変化を示すようになった。この特性を利用すると、フォトマスクで光を照射したところのみ色が変化するフォトクロミックゲルが得られるようになる。最近では、環動ゲルというこれまでのゲルと比べて機械的強度が改良されたゲルにも構造色を発現させることができた。環動ゲルを用いることで、ゲルの機械的強度も強くなることから、構造色変化の繰り返し変化能の向上が実現できると思われる。また、モノマー組成や架橋剤の量などを予め調節すれば、同じ種類のゲルでも異なる色を示すようになる。このようなゲルは、環境センサーや化学センサーなどへの応用が期待できるだろう。
    さらに、ポーラスな構造を導入したことで、一枚のゲル膜中に異なる膨潤度が共存可能になるため、本構造色ゲルでは複数の色が一枚のゲル上に表現できるようになった。このゲルは、迅速な色変化を引き起こすことが可能なことから、様々な刺激に応答して構造色の迅速な二状態スイッチングを示す系が得られる。

  16. Development of New Photo-triggered Mass Transport Systems

    Grant number:16205019  2004 - 2006

    SEKI Takahiro

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    Authorship:Coinvestigator(s) 

    Az polymers are potentially useful as materials for reversible holographic information storage and photonic devices. Surface relief gratings (SRG) formed via irradiation with an interference pattern of coherent light have been demonstrated. We have developed highly sensitive photo-activated mass migration systems using LC binary component materials comprised of an azopolymer and a liquid crystal molecule or azopolymers containing a soft segment. The energy level is three orders of magnitude smaller than those required for conventional amorphous polymer systems hitherto reported. This efficient migration is found to be due to the photoinduced phase transition of a smectic phase to an isotroipic one. In the our migrating system, the quick motion itself can be a valuable function. An application as a "molecular conveyer" for patterning of light-inert (non-photoresponsive) functional materials can be presented. Functional materials, such as dye molecules, conjugated polymers, and semiconductor quantum dots, can be conveyed by the massive motion of the Az polymers. Azobenzene unit is essential for the photo-induced mass migration, but after the relief formation the existence of this strongly light absorbing chromophore will be a severe drawback for many optical applications. To overcome these contradictory requirements, a system in which the Az unit can be detached after the relief formation is proposed. Here the Az unit is not necessarily linked to the polymer backbone, but the supramolecular liquid crystalline framework via hydrogen bonding (Kato system) is applied. After the crosslinking mentioned above, the Az unit is readily removed from the film with retention of the morphological feature of the relief structure. The present proposal can be a facile and versatile method for bleaching the SRG film.

  17. フォトニックバンドギャップを有するアドバンスソフトマテリアルの創製とその光学特性

    Grant number:15033226  2003 - 2004

    竹岡 敬和

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    Authorship:Principal investigator 

    Grant amount:\5000000 ( Direct Cost: \5000000 )

    これまで、粒径の揃ったサブマイクロメーターの球状シリカ球から形成される最密充填型コロイド結晶(以下コロイド結晶とする)を鋳型に用いてゲルを調製し、その後、シリカ成分をエッチングすると、コロイド結晶の構造を象った周期的に繋がった細孔を有するゲルが得られることを報告してきた。そのゲルは、従来のゲルに比べて、膨潤収縮の体積変化速度が千倍以上速い高速応答を示すことがわかった。また、屈折率が可視光のスケールで周期的に変化することから、特定の波長の可視光を反射するため、その構造に基づく発色(構造色)が観測されることを明らかにしてきた。さらに、ゲルの膨潤度の変化に伴って、その周期性も変わることから、構造色にも変化を来すことを見出した。その後、特定のアルカリイオンやグルコースの濃度を検知して、任意の構造色を示すゲルについても開発することができた。例えば、グルコース応答性ゲルは、そのモノマー濃度、架橋剤濃度などをゲル化溶液の段階で調節することで、特定のグルコース濃度にて望みの膨潤度を示すゲルを作ることができる。そこで、糖尿病の診断基準となる濃度に沿って、低濃度(健康な状態)では緑色、境界領域(血中濃度で7.8mM〜11mMが境界領域)で黄色、危険領域(糖尿病)で赤色を示す信号型グルコースセンサーゲルの開発に成功した。その他にも、特定のイオンや光、電場などの物理的にも応答して構造色を変化させるセンサーの構築にも成功している。

  18. ソフトマテリアルへのメソスコピックな立体規則構造の付与とその光学的性質の評価

    Grant number:14750707  2002 - 2003

    竹岡 敬和

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    Authorship:Principal investigator 

    Grant amount:\3100000 ( Direct Cost: \3100000 )

    本研究は感温性モノマーと電解質モノマーの共重合により温度、pH、イオン強度などの外部刺激に応答する感温性高分子電解質ゲルを、最密充填型シリカコロイド結晶を鋳型に用いて合成し、様々な外部環境変化に応じて構造色変化応答を示すようなソフトマテリアルを創製することを目的とした。
    二年間の研究を通して、サブマイクロスケールオーダーの単分散性シリカ微粒子からなる最密充填型シリカコロイド結晶を鋳型として得られる多孔質ゲルが鋳型の構造を保持することで構造色を示し、さらに、ゲルの体積変化に伴いその色調を変化させることを明らかにした。また、感温性モノマーと電解質モノママーの共重合により得られた多孔質ゲルのバッファー中における反射スペクトル測定より、ゲルの体積変化に伴う最大反射波長λ_<max>の変化および色調の変化が観測された。さらに、この、λ_<max>の変化量はゲル網目中の固定イオン基含有量の増加に伴い大きくなることがわかった。同様に、温度、イオン強度変化による多孔質ゲルから観測されるλ_<max>のシフトも確認できた。
    以上より、ゲルにシリカコロイド結晶の持つ微細な規則構造を保持させることで温度、pH、イオン強度といった外部刺激に応答し、構造色を変化させるゲルを得ることに成功した。

  19. 構造色発現現象により水素結合形成を検知するソフトマテリアルの創製

    Grant number:14045227  2002 - 2003

    竹岡 敬和

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    Authorship:Principal investigator 

    Grant amount:\3500000 ( Direct Cost: \3500000 )

    これまでの研究において、環境に応じて大きさや形が変化するソフトマテリアル(ゲル)に構造色発現機能を付与することを試みてきた。高分子鎖が化学的に架橋された三次元網目構造の隙問に溶媒を蓄えた状態にあるゲルを用いると、環境に応じたゲルの大きさの変化(長さ、体積、重さ)を観測することで、ゲルを構成する一本一本の高分子の溶液中での振る舞い(広がり方)を解析できる。従来、非常に困難であった溶液中における高分子鎖の振る舞いを観測することが、ゲルとして扱うことで非常に容易になったのである。つまり、ゲルはフラスコ内で生じている分子レベルの挙動を肉眼で観測できるようにする材料であると考えている。この考えをさらに発展させるために、光の波長レベルの微細周期構造を刻み込むことで、体積の変化を構造色の変化としで捕らえられることを見出した。長さ、体積、重さを測定する場合は環境に伴って生じるゲル内の変化の平均を観測していたが、構造色を示すゲルを観測することでゲルの微細な部分における変化がより詳細に観測できるようになった。このような変化に伴う情報量の増大は、フラスコ内の環境変化に対応した情報をダイナミックに伝えてくれる。"フラスコ内で生じている分子レベルの挙動を、ゲルという材料を通して肉眼で見ることで理解できるようにしたい"という哲学が、本研究提案の根底にある。
    本研究では、"様々な構造色を付与したゲルの研究"を通して分かった知見を基に、特定分子との間に、水素結合、双極子-イオン結合、共有結合を形成することで膨潤度を変化させるゲルを構築し、その構造色変化として捕らえることのできるバイオ・ケミカルセンサーの構築を遂行した。その結果、特定のイオンおよびグルコースを検知して、構造色を変化させるゲルを構築することができた。本センサーに利用する構造色変化を利用した光学的検知方式は、従来のセンサーのようなデバイスに大きな電圧を負荷する電気化学的方法や強い光源を利用した方式とは異なり、デバイスにおけるエネルギーのやりとりがほとんどないことから、省電力で材質安定性の高いシステムの開発が可能となる。

  20. イオン伝導性高分子を電子移動反応場に用いた機能界面の形成と高効率固体電池

    Grant number:11118229  1999

    特定領域研究(A)

    今林 慎一郎

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    Authorship:Coinvestigator(s) 

    安全性とエネルギー・環境問題の点から、イオン伝導性高分子を電解質として用いた固体リチウム二次電池の実現が期待されている。この実現のためには高分子固体電解質(SPE)のイオン導電率向上と共にSPE/電極活物質間の迅速な電子移動反応の達成が必要であるが、SPEは電極物質に対する濡れ性、浸透性が著しく低いために迅速な電子移動反応を可能とする機能界面の形成が難しい。本研究では電極/SPE間の迅速な電子移動反応を可能とする機能界面の構築を目的として、エチレンオキシドとプロピレンオキシドの共重合体のトリアクリレートをUV硬化して形成したSPEマトリックス中でピロールを定電流電解重合してポリピロール(PPy)からSPEへ組成が連続的に変化した傾斜複合膜を作成し、その電気化学的特性を検討した。XPS分析によってPPyが傾斜構造を有してSPE中に生成していることが確認された。100℃において、対極・参照極にLiを用いて測定した複合膜のサイクリックボルタモグラムは、ClO_4のドープ・脱ドープに伴う酸化・還元ピークが観測され、PPy/SPE界面で迅速なClO_4^-の移動が起きていることが分かった。PPyの電位をLi極に対して変化させて行った複素インピーダンス測定は、PPy/SPE界面の抵抗値[R_<ct>]がPPyの電位が正になるほど小さくなることを示した。PPyがほぼドープされた状態にある3.1VにおいてはSPE|Li界面のR_<ct>の約半分であり、PPy/SPE界面で迅速な電荷移動が起こっていることが裏付けられた。これは複合膜中に両高分子が相互に混合した良好な機能界面が形成されていることを示している。電解重合中、SPE中のLi^+がLiとしてカソード表面に析出することが観察され、PPy/SPE|Liで構成される固体電池は充放電特性を持つことを確認した。この結果は、本方法により固体電池を一段階の電解重合によって形成できる可能性を示す。

  21. Chemical Energy and Information Conversion by Utilizing Molecular Synchronization of Polymer Networks

    Grant number:11167234  1998 - 2002

    WATANABE Masayoshi

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    Authorship:Coinvestigator(s) 

    In polymer networks whose structures are determined by the balance between weak intermolecular-interactions, such as hydrogen bonding, ion-dipole, electrostatic, and hydrophobic interactions, it is frequently observed that a tiny fluctuation toward functional groups in the network polymers is quantitatively converted to a different fluctuation, which is transferred, in a spatially and chronologically synchronized manner, over the whole networks. In other words, the weakly correlated polymer networks function not only as a structural network but also as a network for transferring and converting energy and information. This research has been aimed at proposing a new methodology for the design of new materials system for chemical energy and information conversion by revealing "molecular synchronization" in the molecular level. In this research, the following three projects have been studied
    1. In-situ polymerization of vinyl monomers in ionic liquids to form "ion gels" and their utilization in chemical energy conversion.
    2. Electron transfer reaction of glucose oxidase modified with phenothiazine-labeled PEG for efficient chemical information conversion.
    3. "Structurally-colored gels" prepared by using closest packing silica colloid crystals as a template and their structural color change in response to external stimuli.

  22. Synthesis of Hyperbranched Polyether Macromonomers and Ion-conducting Behavior of Their Polymer Electrolytes

    Grant number:10650878  1998 - 1999

    WATANABE Masayoshi

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    Authorship:Coinvestigator(s) 

    Progress of the study of ion-conducting polymers stimulates to alter conventional electrochemical systems, which consist of electrolytes and liquid electrolytes, to solid electrochemical systems. Polymer electrolytes have, thus, occupied an important position in solid state electrochemistry, because of their unique properties, such as thin film forming property, good processability, flexibility, light weight, elasticity (plasticity), and transparency as well as relatively high ionic conductivity and wide potential window in the solid states. Especially, it has been considered to be important and promising to apply polymer electrolytes to solid-state lithium/polymer batteries, which ensure safety, high energy density, freedom in shape geometry, and processability in large-scale-production. The development of large-scale high-energy-density rechargeable lithium/polymer electrolyte batteries, applicable to electric vehicles, is one of the most challenging science and technology in solid state electrochemistry.
    Polymer electrolytes are solid solutions of electrolyte salts in ion-conducting polymers and exhibit relatively high ionic conductivity at ambient temperatures. Ion transport in the polymer electrolytes is considered to be cooperative with local segmental motion of the polymers. In this study, polyether-based ion-conducting polymers having free chain ends in high densities have been prepared as matrixes for electrolyte salts. Our working concept of this study to achieve highly conducting polymer electrolytes is that fast molecular motion of short and flexible ether side chains in the matrix polymers would contribute to fast ion transport. 2-(2-Methoxyethoxy)ethyl glycidyl ether (MEEGE) has been copolymefized with ethylene oxide (EO) to obtain P(EO/MEEGE) as the matrix polymers. EO and MEEGE were copolymerized by KOH-catalyzed ring-opening anionic polymerization in the presence of 2-(2-methoxyethoxy)ethanol to give OH-terminated oligomers, followed by esterification reaction of the OH groups by acrylic acid to give P(EO/MEEGE) macromonomers. The macromonomer/salt solutions containing a photo-initiator were cast on glass plates and irradiated with UV light, resulting to from network polymer electrolytes. The conductivity for the network polymer electrolytes, which give the best conductivity in this study, reaches 10ィイD1-4ィエD1 ScmィイD1-1ィエD1 and 10ィイD1-3ィエD1 ScmィイD1-1ィエD1 at 30℃ and at 80℃, respectively, and even at 0℃ it is close to 10ィイD1-5ィエD1 ScmィイD1-1ィエD1. Although LiィイD1+ィエD1 transport number of the polymer electrolytes is lower than 0.5, as is generally seen polyether based polymer electrolytes, the electrochemically stable domain is wider than 4 V vs. Li/LiィイD1+ィエD1. The presence of the conductivity maximum as a function of the macromonomer molecular weight, irrespective of the constant Tg, indicates that the dendritie-side-chain motion that can not be scaled by Tg and mainly affects the fast ion transport. The introduction of hyper-branched structure is quite effective to achieve fast ion transport in polymer electrolytes.

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Teaching Experience (On-campus) 9

  1. 構造・電気化学

    2016

  2. 分子組織工学特論

    2015

  3. 構造・電気化学

    2015

  4. 構造・電気化学

    2014

  5. 分子組織工学特論

    2013

  6. 構造・電気化学

    2013

  7. 構造・電気化学

    2012

  8. First Year Seminar A

    2011

  9. 分子組織工学特論

    2011

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Teaching Experience (Off-campus) 1

  1. 分子組織工学特論

    Nagoya University)