SYNDIOTACTIC POLYSTYRENE ETHYLBENZENE COMPLEX - CHAIN CONFORMATIONS AND PHASE-BEHAVIOR/

Syndiotactic polystyrene (sPS) has been studied, primarily in the delt a (solvent-stabilised) and gamma phases. Crystallisation from dilute e thylbenzene solution at 40 degrees C leads to a lamellar morphology, w ith a similar unit cell for the polymer/solvent complex as that propos ed by Chatani et al for the sPS/toluene complex [1]. As the temperatur e is raised, the X-ray long period increases in the temperature range of decomplexation, becoming constant in the gamma phase before increas ing again on annealing in tile alpha phase. Neutron scattering measure ments show negligible isotopic fractionation and only a small increase in the radius of gyration in the plane of the sedimented delta phase mats (R-xy) with increasing molecular weight. Together with model simu lations which reproduce satisfactorily both the form of Kratky plots a nd the values for R-xy, this evidence points strongly towards a sheetl ike structure (as is obtained for other non-complexing solution-grown polymer crystals). Increases in R-xy. and changes in the scattering cu rves fi om those characteristic of sheetlike structures in the gamma p hase are interpreted as indicating movement of crystal stems out of th e sheers.