THE EFFECT OF ATTRACTIONS ON THE STRUCTURE AND THERMODYNAMICS OF MODEL POLYMER BLENDS

Molecular dynamics (MD) simulations were carried out on a blend of 50 unit, pearl-necklace chains with the object of examining-the effect of intermolecular attractions on the blend structure and thermodynamics, Repulsive interactions were imposed between intermolecular sites so t hat the effective hard core diameter of B type chains was 1.2 times th at of the A type chains. Simulations were performed for a series of ru ns in which the attractive interactions were systematically varied fro m zero to the full Lennard-Jones value. Examination of the radial dist ribution functions revealed that the attractive interactions had very little effect on the blend structure up to the point of phase separati on. Furthermore, we found that perturbation theory accurately predicte d the changes in pressure associated with the variations in the attrac tive strengths. (C) 1997 American Institute of Physics.