Monte Carlo Simulations of Ultrathin Polymer Blend Films: Influence of Interaction Strength on Segregation and Shape of Coils

The influence of the interaction strength on segregation and anisotropy of individual polymer coils is studied by Monte Carlo simulations of chains on a square lattice for a homopolymer blend, a random copolymer/homopolymer blend, and a pure random-copolymer melt. These simulations show that in a two-dimensional blend an increase in interaction strength causes anisotropic swelling of polymer coils. The anisotropic swelling is less pronounced for the random copolymer/ homopolymer blend where intramolecular repulsion also induces internal reorganization of the polymer coils. For realistic values of the interaction parameter segregation of individual coils remains a dominant feature. Therefore, in ultrathin polymer blend films a characteristic microdomain morphology may be present even if both components are miscible.