title: Photoinduced Bending of Self-Assembled Azobenzene-Siloxane Hybrid.
abstract: A novel azobenzene-siloxane hybrid material displaying photoinduced macroscopic motions has been prepared by one-step organosilane self-assembly. Two types of alkoxysilane precursors with either pendant or bridging azobenzene groups were synthesized via thiol-ene click reactions. Hybrid films with well-ordered lamellar structures were obtained by hydrolysis and polycondensation of these precursors. The film with solely pendant azobenzene groups showed reversible and rapid d-spacing variation upon UV-vis irradiation, which was induced by the trans-cis isomerization of azobenzene moieties. The flexible, free-standing film obtained by co-condensation of two types of precursors showed reversible bending-unbending motions upon UV-vis irradiation. The partial cross-linking between the siloxane layers by bridging azobenzene groups was crucial for photoinduced distortion of the film. This film possesses high elastic modulus, good thermal stability, and shows large amplitude of photoinduced bending-unbending over a wide temperature range. This is the first report on photoinduced macroscopic motions of azobenzene-containing siloxane-based materials. These materials possess great potential for applications in smart devices and energy conversion systems.
authors.affiliation: Institute for Nanoscience & Technology, Waseda University , 513 Wasedatsurumaki-cho, Shinjuku-ku, Tokyo 162-0041, Japan.
authors.forename: Sufang
authors.initials: S
authors.lastname: Guo
authors.affiliation: Electronic Materials Research Division, Osaka Municipal Technical Research Institute , 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553, Japan.
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Matsukawa
authors.affiliation: Department of Chemistry and Materials Engineering, Kansai University , 3-3-35 Yamate-cho, Suita-shi, Osaka 564-8680, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Miyata
authors.affiliation: Department of Chemical System Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Okubo
authors.affiliation: Department of Applied Chemistry, Waseda University , 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan.|Kagami Memorial Research Institute for Materials Science and Technology, Waseda University , 2-8-26 Nishiwaseda, Shinjuku-ku, Tokyo 169-0051, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kuroda
authors.affiliation: Department of Applied Chemistry, Waseda University , 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Shimojima