研究者詳細 - 竹岡　敬和

論文 - 竹岡　敬和

分割表示 251 件中 121 - 140 件目／全件表示 >>

An amorphous array of poly(N-isopropylacrylamide) brush-coated silica particles for thermally tunable angle-independent photonic band gap materials 国際誌

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

NEW JOURNAL OF CHEMISTRY 36 巻 ( 11 ) 頁： 2171 - 2175 2012年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：New Journal of Chemistry

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

DOI： 10.1039/c2nj40368d

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Photoinduced Volume Transition in Liquid Crystalline Polymer Gels Swollen by a Nematic Solvent 査読有り

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

ACS MACRO LETTERS 1 巻 ( 11 ) 頁： 1357 - 1361 2012年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ACS Macro Letters

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 (TNIG). UV irradiation at a temperature slightly lower than TNIG 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 nm 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. © 2012 American Chemical Society.

DOI： 10.1021/mz300447j

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Angle-independent Structural Coloured Amorphous Arrays

Y. Takeoka

J. Materials Chemistry 22 巻頁： 23299-23309 2012年4月

Angle-independent Structural Coloured Amorphous Arrays

Y. Takeoka

J. Materials Chemistry 22 巻頁： 23299-23309 2012年4月

Fabrication of mono-dispersed spherical assemblies and these structural colors by using microflow device 国際誌

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 頁： 644 - 646 2012年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Proceedings of the 16th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2012

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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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 36 巻頁： 2171-2175 2012年

Versatile self-assembled hybrid systems with exotic structures and unique functions 査読有り

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

CURRENT OPINION IN COLLOID & INTERFACE SCIENCE 16 巻 ( 6 ) 頁： 482 - 490 2011年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Current Opinion in Colloid and Interface Science

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. © 2011 Elsevier Ltd.

DOI： 10.1016/j.cocis.2011.08.003

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Multicolor Polymer-Dispersed Liquid Crystals 査読有り国際誌

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

ADVANCED MATERIALS 23 巻 ( 7 ) 頁： 884 - + 2011年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Advanced Materials

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 dem-onstrate 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. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/adma.201003660

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Versatile Self-Assembled Hybrid Systems with Exotic Structures and Unique Functions 招待有り査読有り

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

Current Opinion in Colloid and Interface Science 16 巻頁： 482-490 2011年

Multi-Colour Polymer Dispersed Liquid Crystal 査読有り

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

Adv. Mater. 23 巻頁： 884-888 2011年

Tunable Angle-Independent Structural Colour from Phase Separated Porous Gel 査読有り

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

50 巻頁： 4012-4015 2011年

Tunable Angle-Independent Structural Color from a Phase-Separated Porous Gel 査読有り国際誌

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

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 50 巻 ( 17 ) 頁： 4012 - 4015 2011年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Angewandte Chemie - International Edition

A porous gel exhibiting angle-independent structural color was obtained by a facile self-assembly approach. The porous swollen gel changes color reversibly in response to changes in solvent composition and temperature as a result of changes in the wavelength dispersions of the refractive indices of the gel portion and the solvent portion in the pores. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/anie.201008182

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Precise Synthesis and Physicochemical Properties of High-Density Polymer Brushes designed with Poly(N-isopropylacrylamide) 査読有り

Suzuki, H; Nurul, HM; Seki, T; Kawamoto, T; Haga, H; Kawabata, K; Takeoka, Y

MACROMOLECULES 43 巻 ( 23 ) 頁： 9945 - 9956 2010年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Macromolecules

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/nm2 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 decreaseduptoaround25 °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 °C, the value of the contact angle started to increase dramatically, and it became constant when the solution temperature exceeded 40 °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 ofthe elongated PNIPAs can be positioned on the surfaces or hidden in the vicinity of the membranes, depending on the temperature of the solution. © 2010 American Chemical Society.

DOI： 10.1021/ma101439f

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

Imran Abu Bin, Seki Takahiro, Takeoka Yukikazu

Polymer journal 42 巻 ( 11 ) 頁： 839-851 2010年11月

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

Bin Imran Abu, Seki Takahiro, Takeoka Yukikazu

POLYMER JOURNAL 42 巻 ( 11 ) 頁： 839-851 2010年11月

Poly(N-isopropylacrylamide) Gel Prepared Using a Hydrophilic Polyrotaxane-Based Movable Cross-Linker 査読有り

Bin Imran, A; Seki, T; Ito, K; Takeoka, Y

MACROMOLECULES 43 巻 ( 4 ) 頁： 1975 - 1980 2010年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Macromolecules

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 poly NIPA 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 ∼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. © 2010 American Chemical Society.

DOI： 10.1021/ma902349j

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Angle-Independent Structural Color in Colloidal Amorphous Arrays 査読有り

Harun-Ur-Rashid, M; Bin Imran, A; Seki, T; Ishi, M; Nakamura, H; Takeoka, Y

CHEMPHYSCHEM 11 巻 ( 3 ) 頁： 579 - 583 2010年2月