LIQUID-STATE THEORY OF THE DENSITY-DEPENDENT CONFORMATION OF NONPOLARLINEAR-POLYMERS

We use the two solvation potentials discussed in the previous paper an d polymer reference interaction-site model (PRISM) theory to calculate the mutually consistent single-molecule conformation and liquid struc ture of model linear flexible nonpolar polymers. We focus on the mean end-to-end distance R(2) and radius of gyration R(g) Of the single cha in as functions of polymer density. Our calculations are compared to c omputer simulations to assess their accuracy, and some aspects of the general trends with density predicted are discussed. Two methods of ca lculating the conformation of the single chain in the solvation potent ial are used, one is Monte Carlo simulation, the other, introduced in this paper, employs a generating functional. We cannot unambiguously c onfirm the accuracy of one solvation potential over the other; at low density they give identical results, and the exact values are too few at high density. However, we are inclined to question the accuracy of the hypernetted-chain (HNC) style potential at high densities because it seems to predict a strong contraction of the polymer chain that is not seen experimentally in real polymer melts.