INTERFACES IN PARTLY COMPATIBLE POLYMER MIXTURES - A MONTE-CARLO SIMULATION APPROACH

The structure of polymer coils near interfaces between coexisting phas es of symmetrical polymer mixtures (AB) is discussed, as well as the s tructure of symmetric diblock copolymers of the same chain length N ad sorbed at the interface. The problem is studied by Monte-Carlo simulat ions of the bond fluctuation model on the simple cubic lattice, choosi ng N = 32 and lattice linear dimensions L x D x L up to 512 x 64 x 512 , and using massively parallel computers (GRAY T3D). While homopolymer coils in the strong segregation limit are oriented parallel to the in terface, the diblocks form ''dumbbells'' oriented perpendicular to the interface. However, in the dilute case (''mushroom regime'' rather th an ''brush regime''), the diblocks are only weakly stretched. Distribu tion functions for monomers at the chain ends and in the center of the polymer are obtained, and a comparison to the self-consistent field t heory is made. (C) 1998 Elsevier Science B.V. All rights reserved.