Structural and morphological features of the syndiotactic polystyrene/ethylbenzene complex

Abstract

The δ-phase of the syndiotactic polystyrene/ethylbenzene system, as formed by crystallisation from dilute solution, is shown to result in a lamellar morphology, with a monoclinic crystal lattice similar to that already reported for the complex with toluene. Combined SAXS, FTi.r., d.s.c. and t.g.a. measurements show that an increase in the X-ray long period between 80 and 120°C is related to solvent loss and decomplexation. There is also some temporary loss in helical order. SANS measurements on the δ-phase reveal negligible isotopic fractionation. The small increase in the in-plane radius of gyration with increasing molecular weight is interpreted as evidence of a sheetlike molecular conformation, with superfolding at higher molecular weights leading to a multiple sheet structure. On transformation to the solvent-free γ-phase, an increase in radius of gyration results from a displacement of crystal stems out of the δ-phase sheets.