SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERS CONTAINING A SILOXANE SPACER .1. SYNTHESIS OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERS CONTAINING SILOXANE BOND IN THE SPACER UNIT

Side-chain liquid-crystalline polymers containing siloxane bond in the spacer units were prepared. For the synthesis of the desired monomers, novel silanol compounds carrying a mesogenic group were prepared as the intermediates. The polymers were obtained by ordinary free-radical polymerization. As the mesogenic groups, p- or p'-cyano-substituted biphenyl group, phenyl and biphenylyl benzoates were chosen, and the structural effects on the thermal properties were investigated. Introduction of a disiloxane group in the side chain resulted in a decrease of T(g) which was more marked for longer siloxane units. Furthermore, only when a terphenylene-type mesogen was introduced, a stable smectic mesophase was observed with wide range of phase stability.