SYNTHESIS AND CHARACTERIZATION OF POLYSTYRENE-POLYESTER LIQUID-CRYSTALLINE BLOCK-COPOLYMERS

Liquid crystalline (LC) black copolymers comprising polystyrene and Le polyester blocks were obtained by a three-step procedure. In a first step, hydroxyl-terminated oligoesters were obtained by polycondensatio n reaction of methylhydroquinone and 4,4'-dicarboxy-1,10-dibenzoyloxyd ecane in pyridine solution in the presence of tosyl chloride and dimet hylformamide. Hydroxyl-terminated oligoesters were then further polyme rized with 4,4'-azo-bis(4-cyanopentanoyl chloride) to form azo-macroin itiators which, in a third step, were employed in the free-radical pol ymerization of styrene to form block copolymers. The thermal and LC pr operties of the copolymers are presented and discussed in terms of the dependence upon the molecular weight of the polystyrene block.