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Proceedings Paper

The unique optical and physical properties of soft, transparent, stimulus-sensitive nanocomposite gels
Author(s): Kazutoshi Haraguchi; Huan-jun Li; Liyuan Song
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Paper Abstract

A new type of polymer hydrogel with a unique organic (polymer)/inorganic (clay) network structure has been synthesized by the in-situ free-radical polymerization of N-isopropyl acrylamide (NIPA) in the presence of exfoliated clay platelets in an aqueous medium. The resulting nanocomposite hydrogels (NC gels) consisting of PNIPA and clay (hectorite) exhibit extraordinary optical, mechanical and swelling properties. NC gels also show a clear phase transition due to the coil-to-globule transition of the PNIPA chains. It was observed that the phase-transition temperature (lower critical solution temperature: LCST), defined as the onset temperature of a steep transmittance drop, shifts to a lower or higher temperature than that of pure water (≅ 34 °C) when conditions are altered. When an inorganic salt, such as NaCl, CaCl2 and AlCl3, was added to the surrounding water, the LCST of the NC gels generally shifted to a lower temperature, in a manner almost inversely proportional to the salt concentration. On the other hand, when the NC gels adsorbed cationic surfactant, e.g. hexadecyl trimethyl ammonium chloride, the LCST shifted toward a higher temperature, although the shift and its profile strongly depended on the adsorption conditions, such as the surfactant concentration and the adsorption time. Consequently, non-thermo-sensitive NC gel was obtained by using a surfactant aqueous solution with a concentration higher than the critical micelle concentration.

Paper Details

Date Published: 12 September 2007
PDF: 11 pages
Proc. SPIE 6654, Liquid Crystals XI, 66540O (12 September 2007); doi: 10.1117/12.734714
Show Author Affiliations
Kazutoshi Haraguchi, Kawamura Institute of Chemical Research (Japan)
Huan-jun Li, Kawamura Institute of Chemical Research (Japan)
Liyuan Song, Donghua Univ. (Japan)

Published in SPIE Proceedings Vol. 6654:
Liquid Crystals XI
Iam Choon Khoo, Editor(s)

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