Intramolecular screening effects in nondilute polymer solutions: An equation-of-state approach

In a previous article, we presented a simple modification of the traditional Flory-Huggins theory that took intramolecular screening effects (or same chain contacts) into account. In this article, we present a natural extension of that work, in which free-volume effects are also explained with an equation-of-state model. The predictions of the interaction parameter, chi, for several polymer-solvent systems are presented, over the entire concentration range, in theta solvents and good solvents. A geometric mean assumption is applied to the calculation of an exchange energy interaction term. The predictions of chi are successful to various degrees when internal pressures are used, whereas the use of solubility parameters in most cases produces fairly good agreement with experimental results. (C) 2003 Wiley Periodicals, Inc.