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 s hown to strongly influence the surface segregation in blends of deuter ated 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 compare d to the bulk value, even after annealing for several days at 150-degr ees-C. A low molecular weight blend containing the fluoro-end-capped d euteropolymer showed immediate surface segregation, which increased to give ca. 60% deuterated polymer at the surface after annealing. A sim ilar blend, but with the fluoro end cap on the hydrogenous polymer, ex hibited a surface enrichment of 41% of the hydrogenous component. Anne aling a high molecular weight blend of hydrogenous and deuterated poly styrenes at 155-degrees-C resulted in the gradual segregation of the d euterated component to the surface. A blend of high molecular weight f luoro-end-capped deuterostyrene and hydrogenous styrene showed an incr eased rate of segregation under the same conditions.