SURFACE SEGREGATION IN BLENDS OF HYDROGENOUS POLYSTYRENE AND PERFLUOROHEXANE END-CAPPPED DEUTERATED POLYSTYRENE, STUDIED BY SSIMS AND XPS

End capping a polystyrene with perfluorooctyldimethylchlorosilane is shown to strongly influence the surface segregation in blends of deuterated and hydrogenous polystyrenes. The surface composition, determined by static secondary ion mass spectroscopy, of a low molecular weight blend containing 0.14 mole fraction deuterated polystyrene, end capped by proton donation from methanol, was only slightly increased compared to the bulk value, even after annealing for several days at 150-degrees-C. A low molecular weight blend containing the fluoro-end-capped deuteropolymer showed immediate surface segregation, which increased to give ca. 60% deuterated polymer at the surface after annealing. A similar blend, but with the fluoro end cap on the hydrogenous polymer, exhibited a surface enrichment of 41% of the hydrogenous component. Annealing a high molecular weight blend of hydrogenous and deuterated polystyrenes at 155-degrees-C resulted in the gradual segregation of the deuterated component to the surface. A blend of high molecular weight fluoro-end-capped deuterostyrene and hydrogenous styrene showed an increased rate of segregation under the same conditions.