Statistical Thermodynamics of Polymer Solutions. II. Excluded Volume Effect and Second Virial Coefficient

Abstract

A recently published theory of the second virial coefficient in polymer solutions is modified to take account of the fact that in a good solvent the mean dimensions of two interacting linear molecules are increased beyond random‐flight size through both intermolecular and intramolecular mutual volume exclusion among chain segments. Since the model for a bimolecular cluster bears a formal resemblance to a cruciform branched chain, a method for calculating the dimensions of such polymers can be applied to the two‐molecule problem. This treatment improves the agreement of calculated virial coefficients with experiment as compared with the simpler assumption, made in the original formulation of the theory, that each molecule of an interacting pair is expanded independently in consequence of intramolecular interactions alone.