Segregation at the Interface between a Homopolymer and a Binary Polymer Blend.

Low-energy forward-recoil spectrometry studies show that the interface between polystyrene sAd and a miscible blend of two poly(styrene-co-4-bromostyrene)s sB:Cd has an interfacial excess of B, z B, where B is the component with the lower bromostyrene level. At 170 ±C, z B increases with the bulk volume fraction of B, fB`, has a maximum near 0.25, and then decreases. These results are in qualitative agreement with self-consistent field (SCF) calculations. SCF calculations of the interfacial tension and interfacial width predict that B has an optimum compatibilizing effect for fB` , 0.25.