Dependence of the transitional properties of polystyrene-based side-chain liquid-crystalline polymers on the chemical nature of the mesogenic group (original) (raw)

The synthesis and characterization of side-chain liquid crystal polymers baaed on atactic polystyrene and derivatized with differing mesogenic groups are described. These groups are cyano-, methoxy-, nitro-, and fluoroazobenzene and cyanobiphenyl. In each caw a butyl spacer is used to link the mesagenic 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 temperaturea on the molecular structure of the mesogenic unit was found to be in accord with the behavior obaerved 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. OMe Azo-OMe with phenol to yield 4-hydro~y-4~-subntituted ambenzene, 1, was performed by a standard method.# 4Cyano-4f-hydroxybiphsnyl was used as received from American Tokyo Kaaei, Inc. W other matariala were used as received from Aldrich Chemical Co.