Faculty Profiles - TAKEOKA, Yukikazu

Papers - TAKEOKA, Yukikazu

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*Thermally-Adjustable Multicolor Photochromic Hydrogel Reviewed

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

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

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

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

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

Biform Structural Colored Hydrogel For Observation of Subchain Conformations Reviewed

Takeoka, Y., Seki, T.

Macromolecules Vol. 40 page： 5513-5518 2007

*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

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

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

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

Web of Science

Scopus

A thermally adjustable multicolor photochromic hydrogel

Matsubara Kazuki, Watanabe Masayoshi, Takeoka Yukikazu

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

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

A thermally adjustable multicolor photochromic hydrogel

Matsubara Kazuki, Watanabe Masayoshi, Takeoka Yukikazu

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

A thermally adjustable multicolor photochromic hydrogel

Matsubara Kazuki, Watanabe Masayoshi, Takeoka Yukikazu

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

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

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

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

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

Web of Science

Scopus

PubMed

Visualizing Conformations of Subchains in Structural Colored Gel

TAKEOKA Yukikazu

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

Language：English Publishing type：Research paper (scientific journal) Publisher：THE MEMBRANE SOCIETY OF JAPAN

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

DOI： 10.5360/membrane.31.296

CiNii Books

CiNii Research

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

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

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

Web of Science

Scopus

PubMed

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

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

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

HAYATA Yuki, NAGANO Shusaku, TAKEOKA Yukikazu, SEKI Takahiro

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

Language：English Publishing type：Research paper (scientific journal) Publisher：THE JAPANESE LIQUID CRYSTAL SOCIETY

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

CiNii Research

Structural Colored Gel

TAKEOKA Yukikazu

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

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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Papers - TAKEOKA, Yukikazu