MONTE-CARLO SIMULATIONS OF SYMMETRICAL POLYMER BLENDS - II - CHAIN PROPERTIES IN INTERFACE REGIONS

Making use of a previously introduced lattice model for binary polymer blends of limited miscibility Monte Carlo simulations have been perfo rmed in order to investigate the influence of different thermodynamic conditions on mass segregation and global structure as well as on micr ostructure of homopolymers when passing from one bulk phase through th e interface to the other. The calculations show an enrichment of short er chains at the interface as well as a decreasing miscibility with de creasing average chain length (at constant bulk density) of the polyme r matrix on the one hand and relate the compression of the coils at th e interface to the observed orientation and deformation effects on the other. Surprisingly, an additional expansion of the polymer coils (be longing to the minority component) can be found at some distance from the actual interface due to attractive interactions between pairs of c hains in rather ''diluted'' layers. Furthermore, all phenomena are dis cussed from two different viewpoints: (i) The average chain length is kept constant while the energy parameter is varied, and (ii) the chain length is varied and the bulk densities an held constant by use of id entical relative energy parameters. (C) 1998 American Institute of Phy sics.