ELECTRICAL AND OPTICAL ALIGNMENT PROCESSES IN SOME NOVEL LIQUID-CRYSTALLINE SIDE-CHAIN POLYMERS AS STUDIED BY DIELECTRIC-RELAXATION SPECTROSCOPY

Dielectric relaxation spectroscopy has been used in the present work t o study the extent of the macroscopic alignment that is induced in som e novel liquid-crystalline (LC) side-chain polymers containing either photoactive cyanoazobenzene groups or cyanoazobenzene groups interdisp ersed along the chain by nonactive cyanobiphenyl groups. The effects o f an applied ac electric field on the cyanoazobenzene mesogenic side g roups in a LC homopolymer (LC1) and a LC copolymer (LC2) have been stu died. Also, the actions of polarized laser radiation (514 nm mode-lock pulse) on the copolymer via an isomerization mechanism of the cyanoaz obenzene moieties have been examined. The changes with temperature thr ough the liquid-crystalline phase to the clearing temperature in the l oss part of the complex permittivity of the samples measured in the fr equency plane give a good qualitative indication of the changes of ali gnment that are being induced by light or an electric field since the delta-relaxation process and other component processes may be used as indicators of macroscopic alignment.