Molecular Orientation and Thermal Diffusivity of Side-Chain Liquid Crystal Polymer Thin Films with Smectic Phases

Abstract

Side-chain liquid crystalline (SCLC) polymersexhibiting smectic (Sm) A, C and E phases were synthesized by randomcopolymerization of azobenzene and cyanobiphenyl monomers. We evaluated thermaldiffusivity in the through-plane direction of the SCLC polymer films withthicknesses ranging from 500 to 1500 nm. TheLC orientation in thin films was analyzed by grazing incidence x-ray scattering(GI-XRS) and infrared p-polarized multiple-angle incidence resolutionspectrometry (IR pMAIRS). The thermal diffusivity in thin films was suppressed comparedwith bulk. This indicates that the homeotropic orientation of SCLC polymers inthin films suppresses the phonon diffusion in the out-of-plane direction. Moreover, we discussedthe relation between the LC orientation and thermal diffusivity by controllingthe LC orientation of the thin films.