Polymer, Vol.46, No.23, 9549-9554, 2005
Polymorphism of syndiotactic polystyrene: gamma phase crystallization induced by bulky non-guest solvents
The crystallization of amorphous syndiotactic polystyrene (s-PS) films when induced by bulky solvents, whose molecules are too big to be enclosed as guest of s-PS clathrate phases, generally leads to the formation of gamma-phase. This kind of solvent induced crystallization in amorphous films generates a preferential (200) uniplanar orientation of the gamma-crystalline phase. Moreover, the presence of highly boiling solvents in the amorphous phase of these gamma-form samples can induce a gamma - beta phase transition, as a consequence of thermal annealing procedures at atmospheric pressure. A comparison with literature data suggests that the formation of the thermodynamically stable beta-phase is generally favored with respect to the formation of the kinetically favored alpha-phase, by any s-PS dilution. (c) 2005 Elsevier Ltd. All rights reserved.