STUDIES ON THE THERMOTROPIC LIQUID-CRYSTALLINE POLYCARBONATES .5. SYNTHESIS AND PROPERTIES OF CARBONATO SIDE-CHAIN LIQUID-CRYSTALLINE POLYSILOXANES

Two series of spacer-containing carbonate side chain liquid crystalline polysiloxanes were prepared by hydrosilylation of various novel allyl carbonates with poly(hydrogen-methylsiloxane). The thermotropic liquid crystalline properties of synthesized monomers and polymers were investigated by: (1) examination of the melt birefringence and stirred opalescene by a polarizing microscope equipped with a heating stage; (2) characterization of mesophase transitions by a differential scanning calorimeter (DSC); and (3) analysis of dielectric properties, conductivity and phase transition by a dielectric analyzer (DEA). It was found that most of the synthesized polymers with the carbonate groups in the side chains showed excellent mesophase stabilities and low glass transition temperatures. In the meantime, the melting transitions were reduced by introducing longer spacers.