Neutron scattering studies of syndiotactic polystyrene/ethylbenzene

The neutron scattering observed from delta-phase samples of syndiotactic polystyrene (sPS)/ethylbenzene is shown to be consistent with sheet-like arrangements of crystal stems arranged along the a direction. Adjacent stems therefore show an alternation in helicity. Simulations based on a statistical model have been used to calculate statistical parameters, such as the probability of adjacency (P-A) for which optimum agreement is found for a value of 0.8. Radii of gyration obtained from simulations are in good agreement with experimental values. The molecular weight range studied appears to cover the change from a single-sheet structure to a superfolded double sheet. The same stem statistics (with P-A = 0.8) apply, irrespective of molecular weight. Scattering data from the gamma phase of sPS are well reproduced by a model involving some movement of stems out of the planes of the sheets. (C) 1998 Elsevier Science Ltd. All rights reserved