Faculty Profiles - TAKEOKA, Yukikazu

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

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

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

Language：English Publishing type：Research paper (scientific journal) Publisher：The Materials Research Society of Japan

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

DOI： 10.14723/tmrsj.35.291

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

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

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

Language：English Publishing type：Research paper (scientific journal) Publisher：The Materials Research Society of Japan

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

DOI： 10.14723/tmrsj.35.841

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

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

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

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

Vol. in press. 2010

Masaki Honda, Kazunori Kataoka, Takahiro Seki, Yukikazu Takeoka

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

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

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.

DOI： 10.1021/la804262b

PubMed

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 - + 2009.5

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

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

DOI： 10.1002/adma.200801258

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

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

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

DOI： 10.1021/am900074v

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)

PubMed

Structural Colored Gel Invited Reviewed

Takeoka, Y.

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

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

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

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

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

*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

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

Takeoka Yukikazu

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

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japanese Association for Crystal Growth (JACG)

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

CiNii Books

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

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

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

DOI： 10.1039/b900261h