Wetting transition in a binary polymer blend

We have used composition depth profiling, based on nuclear-reaction analysi s and secondary ion mass spectroscopy, to study segregation at the free sur face of a partly miscible binary mixture consisting of random oleifinic cop olymers. The equilibrium surface excess data, analysed within a mean-field Cahn approach, point to a wetting transition. The surface phase diagram obt ained was confirmed by the observed dynamics of the segregation from a coex istence composition: the monotonic and halted growth of the surface layer w as observed at temperatures above and below the predicted wetting point, re spectively.