Surface segregation of components in poly(vinyl chloride)-polydimethylsiloxane and polystyrene-poly(propylene oxide) solvent-cast blends

X-ray photoelectron spectroscopy and scanning electron microscopy are used to study the surface composition and morphology of poly(vinyl chloride)-polydimethylsiloxane (PVC-PDMS) and polystyrene-poly(propylene oxide) (PS-PPO) solvent-cast blends as a function of the blend composition and constituent molecular weights. The PVC-PDMS blends show a pronounced surface enrichment of PDMS, which is higher the lower the molecular weight of PDMS. The surface behavior of the PPO-PS blends is strongly dependent on the solvent used. Despite the much lower surface tension of PPO compared to that of PS, no surface segregation of PPO is observed in the PPO-PS blends cast from tetrahydrofuran, while the blends cast from chloroform exhibit a high surface enrichment of PPO. (C) 1998 John Wiley & Sons, Inc.