Multimolecule glasses and crystals of isotactic polystyrene

When spreading dilute solutions of isotactic polystyrene (iPS) on water, it was observed that different concentrations produce different morphologies in the resulting amorphous films. From 10(-1) to 10(-2) wt% solutions, ribb onlike films and circular platelets of multimolecule aggregates were obtain ed. After isothermal crystallization of these amorphous films, lamellae, in cipient spherulites, and single-molecule crystals were observed. The format ion of lamellar crystals lying flat on the substrate is an indication of th e absence of epitaxy by the substrate, which would require the molecular ch ains to be in the surface plane and thus yield lamellae normal to the subst rate. The dense packing in the center of sheaf-like spherulites is caused b y screw-dislocation growth, and it produces structures similar to shish keb abs. It was also observed that the lamellae grown from the center develop s econdary growth spirals, causing the branching and splaying of the structur e typical for spherulitic growth.