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 that the effective hard core diameter of B type chains was 1.2 times that of the A type chains. Simulations were performed for a series of runs in which the attractive interactions were systematically varied from zero to the full Lennard-Jones value. Examination of the radial distribution functions revealed that the attractive interactions had very little effect on the blend structure up to the point of phase separation. Furthermore, we found that perturbation theory accurately predicted the changes in pressure associated with the variations in the attractive strengths.