Inducing planar orientation in side-chain liquid crystal polymer block by random copolymerization and photo-alignment of POSS block copolymers

Abstract

A planar oriented side-chain liquid crystal (SCLC) random copolymer with azobenzene and cyanobiphenyl side chains was designed. The SCLC block copolymers were synthesized with a caged silsesquioxane (POSS) poly methacrylate at lamellar and cylinder morphologies. The thin films of the block copolymers were prepared and annealed above the isotropic temperature. When the block copolymer thin films were irradiated with linearly polarized light (LPL) at 430 nm, large dichroism was observed at absorption bands due to the mesogenic side-chains. The optical order parameter with cylinder structure was higher than that with lamellar structure. The thin films without annealing process were also irradiated with LPL in the same way. The dichroism was greater than that of the annealed one.