DEPENDENCE OF THE TRANSITIONAL PROPERTIES OF POLYSTYRENE-BASED SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERS ON THE CHEMICAL NATURE OF THE MESOGENIC GROUP

The synthesis and characterization of side-chain liquid crystal polymers based on atactic polystyrene and derivatized with differing mesogenic groups are described. These groups are cyano-,methoxy-, nitro-, and fluoroazobenzene and cyanobiphenyl. In each case a butyl spacer is used to link the mesogenic group to the backbone. The cyano- and nitro-substituted azobenzenes exhibit a partially interdigitated smectic A phase, whereas the methoxy- and fluoro-substituted azobenzenes exhibit a smectic A phase in which the side chains overlap to a considerably greater extent. The dependence of the clearing temperatures on the molecular structure of the mesogenic unit was found to be in accord with the behavior observed for low molar mass mesogens and other side-chain polymers having differing backbones. In contrast, the dependence of the glass transition temperature on the chemical nature of the mesogenic moiety appears to be influenced by the structure of the backbone.