EFFECT OF LONG-RANGE FORCES ON SURFACE ENRICHMENT IN POLYMER BLENDS

Model calculations are made of surface segregation profiles for polyme r and oligomer blends, both for the case in which surface segregation is driven purely by short-range forces, and for the case in which long -range (dispersion) forces are important. As expected, the inclusion o f long-range forces affects the profiles as complete wetting is approa ched, but the effect on the shape of the surface segregation profile f or a high polymer blend in the one phase region of the phase diagram i s small; recent discrepancies between theory and experiment cannot be accounted for by this explanation.