DIFFERENT SURFACE PROFILES IN SURFACE DEMIXING OF POLYMER BLENDS

The surface of the polymer mixture is simulated by Monte-Carlo method via condensing the polymer mixture against the solid wall and examining the free surface parallel with the wall. Depending on interactions present in the mixture and on the composition we find three representative situations of surface segregation effect in polymer mixtures described as segregation in, segregation out, and surface double layer. The segregation occurs across a realistic diffusive surface profile in contrast to theoretical approaches to this phenomenon working with a steplike density profile across the surface. Among the advantages of the present simulation, like the presence of compressibility of the studied system, there are also certain limitations, such as the lattice approximation.