Interfaces in partly compatible polymer mixtures: a Monte-Carlo simulation approach

The structure of polymer coils near interfaces between coexisting phases of symmetrical polymer mixtures (AB) is discussed, as well as the structure of symmetric diblock copolymers of the same chain length N adsorbed at the interface. The problem is studied by Monte-Carlo simulations of the bond fluctuation model on the simple cubic lattice, choosing N=32 and lattice linear dimensions L×D×L up to 512×64×512, and using massively parallel computers (CRAY T3D). While homopolymer coils in the strong segregation limit are oriented parallel to the interface, the diblocks form “dumbbells” oriented perpendicular to the interface. However, in the dilute case (“mushroom regime” rather than “brush regime”), the diblocks are only weakly stretched. Distribution functions for monomers at the chain ends and in the center of the polymer are obtained, and a comparison to the self-consistent field theory is made.