Updated on 2021/03/18

写真a

 
TAKEOKA, Yukikazu
 
Organization
Nagoya University Graduate School of Engineering Molecular and Macromolecular Chemistry 2 Associate professor
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 176

  1. 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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    Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/acsami.0c17687

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    Scopus

  2. 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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    Publishing type:Research paper (scientific journal)  

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

    DOI: 10.1021/acsapm.0c00703

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

    DOI: 10.1021/acsami.0c10588

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

    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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  7. 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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    Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

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

    Takeoka Yukikazu, Liu Sizhe, Asai Fumio

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   Vol. 21 ( 1 ) page: 817 - 833   2020.1

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    Publishing type:Research paper (scientific journal)   Publisher:Science and Technology of Advanced Materials  

    DOI: 10.1080/14686996.2020.1849931

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  9. 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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    Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    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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  10. 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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    Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    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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  11. 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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    Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    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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  12. 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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    Publishing type:Research paper (scientific journal)   Publisher:TAYLOR & FRANCIS LTD  

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

    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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  14. 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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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER ASSOC ADVANCEMENT SCIENCE  

    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.

    DOI: 10.1126/sciadv.aat7629

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

    DOI: 10.1038/s41427-018-0074-x

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

    DOI: 10.1002/smll.201800817

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

    DOI: 10.1002/cnma.201800102

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

    DOI: 10.1039/c8cc01894d

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

    DOI: 10.1021/acs.langmuir.8b00242

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

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

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

    DOI: 10.1039/c7cc09464g

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

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

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

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

    DOI: 10.1038/pj.2016.117

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

    DOI: 10.1002/adma.201605050

  28. 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

  29. 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

  30. 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

  31. 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   2017

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    <p>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.</p>

    DOI: 10.4011/shikizai.90.393

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  32. 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   2017

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    <p>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。</p>

    DOI: 10.20665/kakyoshi.65.12_640

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  33. 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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  34. Preparation of Structural Coloring Material using Functional Black Substance

    TAKEOKA Yukikazu

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

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    <p>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.</p>

    DOI: 10.14356/hptf.14110

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  35. 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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  36. 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.

    DOI: 10.1039/c6cc07641f

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  37. 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.

    DOI: 10.1002/anie.201507503

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  38. 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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  39. 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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  40. 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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  41. 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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  42. 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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  43. Fusion Materials for Biomimetic Structurally Colored Materials Invited Reviewed

    Y. Takeoka

    Polymer Journal   Vol. 47   page: 106-113   2015

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  44. 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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  45. 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

  46. 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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  47. 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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  48. Extremely stretchable thermosensitive hydrogels by introducing slide-ring polyrotaxane cross-linkers and ionic groups into the polymer network Reviewed 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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    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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  49. Production of Colourful Pigments Consisting of Amorphous Arrays of Silica Particles Reviewed International journal

    Shinya Yoshioka, Yukikazu Takeoka

    CHEMPHYSCHEM   Vol. 15 ( 11 ) page: 2209 - 2215   2014.8

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    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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  50. 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

  51. 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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  52. 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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  53. Angle-independent Structural Coloured Materials inspired by Blue Feather Barbs

    TAKEOKA Yukikazu

    NIPPON GOMU KYOKAISHI   Vol. 87 ( 6 ) page: 226-230   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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  54. 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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  55. Structurally Coloured Secondary Particles Composed of Black and White Colloidal Particles Reviewed International journal

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

    SCIENTIFIC REPORTS   Vol. 3   page: 2371   2013.8

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    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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  56. 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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  57. 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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  58. 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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  59. 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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  60. 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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  61. 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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  62. 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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  63. 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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  64. 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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  65. 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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  66. An amorphous array of poly(N-isopropylacrylamide) brush-coated silica particles for thermally tunable angle-independent photonic band gap materials Reviewed 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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    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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  67. 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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  68. Angle-independent Structural Coloured Amorphous Arrays

    Y. Takeoka

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

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  69. Angle-independent Structural Coloured Amorphous Arrays

    Y. Takeoka

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

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  70. 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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  71. 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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  72. 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.

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  73. Multicolor Polymer-Dispersed Liquid Crystals Reviewed 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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    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.

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  74. 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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  75. 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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  76. 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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  77. Tunable Angle-Independent Structural Color from a Phase-Separated Porous Gel Reviewed International journal

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

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 50 ( 17 ) page: 4012 - 4015   2011

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    DOI: 10.1002/anie.201008182

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  78. 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.

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  79. 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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  80. 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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  81. 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.

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  82. 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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  83. 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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  84. 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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  85. 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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  86. 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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  87. 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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  88. 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   2010

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    DOI: 10.14723/tmrsj.35.845

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  89. 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   2010

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    DOI: 10.14723/tmrsj.35.841

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  90. 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   2010

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    DOI: 10.14723/tmrsj.35.291

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  91. 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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  92. 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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  93. 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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  94. 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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  95. Dual Tuning of the Photonic Band-Gap Structure in Soft Photonic Crystals Reviewed International journal

    Masaki Honda, Takahiro Seki, Yukikazu Takeoka

    ADVANCED MATERIALS   Vol. 21 ( 18 ) page: 1801 - 1804   2009.5

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    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.

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  96. Structural Colored Liquid Membrane without Angle Dependence Reviewed International journal

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

    ACS APPLIED MATERIALS & INTERFACES   Vol. 1 ( 5 ) page: 982 - 986   2009.5

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    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.

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  97. 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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  98. Structural Colored Gel Invited Reviewed

    Takeoka, Y.

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

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  99. 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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  100. 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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  101. 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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  102. 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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  103. *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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  104. 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   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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  105. Electrochromism based on structural colour changes in a polyelectrolyte gel Reviewed 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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    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.

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  106. Structural Colored Gel

    Takeoka Yukikazu

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

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  107. 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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  108. 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

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  109. 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   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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  110. 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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  111. 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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  112. 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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  113. *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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  114. *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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  115. 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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  116. 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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  117. Fabrication of mechanically improved hydrogels using a movable cross-linker based on vinyl modified polyrotaxane Reviewed International journal

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

    CHEMICAL COMMUNICATIONS   ( 41 ) page: 5227 - 5229   2008

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

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  118. Photoregulated Wormlike Motion of a Gel Reviewed International journal

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

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 47 ( 47 ) page: 9039 - 9043   2008

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    DOI: 10.1002/anie.200803046

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  119. 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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  120. An electro- and thermochromic hydrogel as a full-color indicator Reviewed International journal

    Kazuhide Ueno, Kazuki Matsubara, Masayoshi Watanabe, Yukikazu Takeoka

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

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    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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  121. Photochromic gels

    TAKEOKA Yukikazu

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

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  122. 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.

    DOI: 10.1021/la700448t

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  123. 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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  124. 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.

    DOI: 10.1021/ma0701078

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

    NAGAYAMA Kuniaki, TAKEOKA Yukikazu

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

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    DOI: 10.1295/kobunshi.56.26

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  127. *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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  128. 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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  129. 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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  130. 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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  131. 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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  132. *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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  133. 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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  134. 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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  135. 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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  136. 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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  137. 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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  138. 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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  139. 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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  140. Visualizing Conformations of Subchains in Structural Colored Gel

    TAKEOKA Yukikazu

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

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    DOI: 10.5360/membrane.31.296

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

    DOI: 10.1021/la060224g

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  142. 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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  143. 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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  144. 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   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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  145. Structural Colored Gel

    TAKEOKA Yukikazu

      Vol. 54 ( 4 ) page: 258-263   2005.4

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  146. 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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  147. 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   2005

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    DOI: 10.1295/kobunshi.54.258

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

    Susan MA, Ishibashi A, Takeoka Y, Watanabe M

    Colloids and surfaces. B, Biointerfaces   Vol. 38 ( 3-4 ) page: 167-73   2004.11

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    DOI: 10.1016/j.colsurfb.2004.01.016

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  149. Structural Colored Gel

    TAKEOKA Yukikazu, WATANABE Masayoshi

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

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    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

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

    Takeoka Y, Watanabe M, Yoshida R

    Journal of the American Chemical Society   Vol. 125 ( 44 ) page: 13320-1   2003.11

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    DOI: 10.1021/ja036904c

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

    Nakayama D, Takeoka Y, Watanabe M, Kataoka K

    Angewandte Chemie (International ed. in English)   Vol. 42 ( 35 ) page: 4197-200   2003.9

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    DOI: 10.1002/anie.200351746

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

    Saito H, Takeoka Y, Watanabe M

    Chemical communications (Cambridge, England)   ( 17 ) page: 2126-7   2003.9

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  154. 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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    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.

  155. 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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  156. 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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  157. 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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  158. 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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  159. 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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  160. 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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  161. 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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  162. 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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  163. 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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  164. 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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  165. 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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  166. 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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  167. 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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  168. 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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  169. 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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  170. 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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  171. 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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  172. 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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  173. 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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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

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

  175. 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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    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)  

  176. 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 H.

    Japanese Journal of Crop Science   Vol. 64 ( 2 ) page: 216-220   1995

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

    DOI: 10.1626/jcs.64.216

    Scopus

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Books 30

  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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    Language:Japanese

  4. 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

  5. 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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    Language:Japanese

  6. 構造発色性ゲル

    ( Role: Sole author)

    2010 

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    Language:Japanese

  7. 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

  8. 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

  9. “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

  10. 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

  11. 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

  12. “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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    Language:Japanese

  13. “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

  14. “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

  15. “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

  16. “ 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

  17. “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

  18. “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

  19. “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

  20. 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

  21. “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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    Language:Japanese

  22. “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

  23. “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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    Language:Japanese

  24. “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

  25. “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

  26. “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

  27. “構造色ゲル ”

    竹岡 敬和( Role: Sole author)

    高分子  2005 

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    Language:Japanese

  28. “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

  29. “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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  30. “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

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Presentations 18

  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. 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

  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. 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

  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. 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

  8. 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

  9. 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

  10. 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

  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. 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

  13. 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)  

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  14. 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)  

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  15. 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

  16. Structural colored gel

    Takeoka Y.

    Polymer Preprints, Japan 

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    Event date: 2005.12

    Language:English   Presentation type:Oral presentation (general)  

    Scopus

  17. 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

  18. 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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    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)