SIMPLE-MODELS FOR INTERACTIONS OF LINEAR-POLYMERS IN DILUTE-SOLUTIONS

A simple mean-field approach that was introduced by DiMarzio for the description of the collapse transition of linear polymers in dilute solutions is extended to the case of interacting polymers. We discuss the potential of mean force between two identical molecules and the resulting second osmotic virial coefficient. In the good-solvent range, this approach yields results which are very similar to those of the Flory-Krigbaum theory. While the direct extension of DiMarzio's approach leads to unphysical behavior near or below the theta-point, a modified treatment which combines elements of both his and Flory and Krigbaum's approach leads to results which are physically reasonable also in the latter case. The theory also yields information on how the average size of interacting molecules changes with their intermolecular separation; the results are in good qualitative agreement with simulation results given in the literature. The paper closes with a discussion of the potential of mean force between a linear polymer and a hard wall.