Phase transitions in thin films of symmetric binary polymer mixtures

We report lattice and off-lattice computer simulation studies on the phase coexistence of symmetric polymer blends confined between two hard walls to which neither component is preferred energetically. We find that the phase diagrams for thin films are always ‘inside’ those for thicker films. While one reason for this is the loss of neighbours due to the presence of the wall, another important factor is the somewhat surprising surface segregation of the minority blend component.