Abstract
Ion beam and surface analysis complemented with optical and electron microscopy are used to analyze the structure of spin-coated films of blends of polystyrene and polybutadiene. Both polystyrene and polybutadiene preferentially segregate to the surface depending on the molar mass of the blend, but only the smallest polystyrene chains dominate surface-enriched layers. Contact angle experiments reveal that the surface energy of the films is dominated by film morphology rather than the surface energy of the individual components. It is concluded that polymer chain mobility in the toluene solvent during spin casting is an important factor in controlling the surface structure.