PHASE ORGANIZATION OF SOLVENT-CRYSTALLIZED SYNDIOTACTIC POLYSTYRENE FILMS

Sorption and diffusion of dichloromethane vapor in the helical forms- that is, delta and gamma-of syndiotactic polystyrene were investigated. The thermal transition from the delta to the gamma form occurs through an intermediate mesomorphic form, also characterized by chains in helical conformation but lacking true crystalline order. The mesomorphic phase was found impermeable to the vapor at low activity, becoming permeable at higher activities. The presence of a mesomorphic phase, along with the crystalline and the amorphous forms, was suggested in the crystallized samples, too, and its fraction increases greatly going from the delta to the gamma form.