SURFACE-MORPHOLOGY STUDIES OF MULTIBLOCK AND STARBLOCK COPOLYMERS OF POLY(ALPHA-METHYLSTYRENE) AND POLY(DIMETHYLSILOXANE)

Surface morphology and compositions of multiblock and starblock copoly mers of poly(alpha-methylstyrene) (PMS) and poly(dimethylsiloxane) (PD MS) were investigated by cross-sectional transmission electron microsc opy, angle- and energy-dependent ESCA, and infrared spectroscopy. The extent of surface segregation of PDMS was determined for multiblock an d starblock copolymers to a depth of 210 angstrom. No surface excess w as detected at depths probed by attenuated total reflectance Fourier t ransform infrared spectroscopy measurements. The PMS-PDMS block copoly mers with high PDMS bulk concentrations (60 wt %) have a highly orient ed lamellar morphology in the near air surface region, and the topmost air surface region (27 angstrom) is exclusively composed of PDMS. The PMS-PDMS block copolymers with lower PDMS bulk concentrations (40 wt %) have lesser or no domain orientation and the surface region include s detectable PMS.