Interfacial properties of elastomer blends as studied by neutron reflectivity

The interfacial properties of a homopolymer (polybutadiene (PB)) and a terp olymer (brominated poly(isobutylene-co-p-methylstyrene) (BIMS)) are reporte d. Neutron reflectivity was used to study the interfacial structure. The re sults were complemented by scanning transmission X-ray microscopy and atomi c force microscopy, which were used to probe the morphology of these binary blends. Our results show that the interfacial behavior of these elastomeri c blends is a direct function of the BIMS chemical composition. The interfa cial width decreased with increasing bromide functionality. At levels below 8 mol%, the para-methylstyrene concentration had a less pronounced effect on the compatibility and interfacial characteristics. We also studied the e ffect of styrene butadiene random copolymers on the miscibility of the PB/B IMS blends. The results showed that styrene-butadiene rubber (SBR) was not fully miscible with BIMS and PB on an individual basis, but addition of rel atively small amount of SBR enhances the compatibilization of the PB/BIMS i nterface. Self-consistent field (SCF) modeling was used to determine the op timum copolymer composition. The calculations are consistent with the exper imental results. (C) 2001 Elsevier Science Ltd. All rights reserved.