Synthesis and characterization of ABA-triblock copolymers with polystyrene and main-chain liquid crystalline polyester segments

This paper reports on the synthesis and characterization of polystyrene-block-poly(2,2'-dimethyl-4,4'-biphenylene phenylterephthalate) -block-polystyrene. The ABA-triblock copolymers were synthesized by condensation reactions of telechelic poly(2,2'-dimethyl-4,4'-biphenylene phenylterephthalate) with anionically prepared omega-hydroxy polystyrenes. Three different lengths of the liquid-crystalline polyester ((M) over bar(n) = 2650, 5500, 10100 g/mol) were used as central block B. The number-average molecular weight (M) over bar(n) of the polystyrene segments was varied in the range of 690 to 10000 g/mol. The liquid crystalline behavior and the transition temperatures are discussed with respect to the molecular weight of the polystyrene segments and the block copolymer composition. A comparison with the corresponding polymer blends is given and first results on the morphology of the block copolymers are presented.