Presentation Information
[8a-PB2-7]Effect of Anneal and Interfacial Conditions on Photoreorientation in Photoresponsive Liquid Crystalline Block Copolymer with POSS Block
〇(B)Misaki Hashimoto1, Yuya Ishizaki2, Shusaku Nagano1 (1.Rikkyo Univ., 2.Shinshu Univ.)
Keywords:
Liquid crystalline polymer,Microphase-separated structures,photo-reorientation
A liquid-crystalline (LC) block copolymer, P(CB-r-Az)-b-PPOSS, synthesized via reversible addition-fragmentation chain transfer (RAFT) random copolymerization using azobenzene (Az) and cyanobiphenyl (CB) methacrylates, followed by block copolymerization using a silsequioxane (POSS) methacrylate. P(CB-r-Az)-b-PPOSS exhibited quite a similar phase transition nature to the LC random copolymer, P(CB-r-Az), indicating the formation of the microphase-separated structure. Small-angle x-ray scattering measurement revealed that P(CB-r-Az)-b-PPOSS adopted a microphase-separated lamellar structure. The block copolymer thin films were prepared by spin-casting and annealed above the isotropic temperature. Before and after heat annealing, the absorption spectrum features of the block copolymer film were almost unchanged, indicating a random planar orientation in the LC block. The reorientation of microphase-separated structures in the thin films was controlled by linear polarized visible light (LPL, 430 nm) irradiation under the liquid crystalline temperature. We conducted LPL irradiation under atmospheric conditions and in the vapor of organic solvents such as acetone. A relatively high dichroism was observed in the solvent vapor conditions. Furthermore, we investigated the effects of solid-state interfaces on photoalignment behaviors by fabricating the block copolymer films on glass substrates and on thin films of water-soluble polymers such as polyvinyl alcohol, and then we conducted the photoalignment process.