Self-Consistent Field Theory of Correlations In Linear/Branched Polymer Blends

Blends of a linear polymer and its branched equivalent have been shown experimentally to exhibit a tendency for the two species to avoid each other on a molecular scale.  This tendency to segregate in the bulk results in density correlations that can be measured by scattering and also produces a demixing contribution to the blend free energy.  We present studies using a self-consistent field (SCF) theory that allows calculation of these correlations, normally neglected in SCF theories, by computing the average density of species around a specified monomer.  We compute intra- and intermolecular radial distribution functions, and demonstrate the role of swelling at crowded branched junctions.  In a linear and star blend, the intramolecular monomer pair distribution function shows a crossover from self-avoiding walk to random walk that depends on the monomer density and excluded volume. As an extension of SCF calculation, the structure factors are compared with the random phase approximation, and can provided a reference for neutron scattering data analysis.