Predicting the Phase Behavior of Polymer Systems with the GC-SAFT-VR Approach

The recently developed heteronuclear group contribution SAFT-VR equation (GC-SAFT-VR) [Peng et al. Fluid Phase Equilib. 2009, 227 (2), 131−144] enables the predictive study of the thermodynamic properties of fluids and their mixtures by using a molecular-based model in which the molecules are described by heterosegmented chains in which each type of segment represents a functional group present in the molecule. Given the success of the GC-SAFT-VR approach in predicting the fluid phase equilibria of mixtures without fitting to any mixture data, and the known difficulties in determining equation-of-state parameters for polymers because of the lack of coexistance data, in this work, we extend the GC-SAFT-VR equation to study the phase equilibria of small molecules in polymer systems. The results demonstrate the ability of the GC-SAFT-VR equation of state to predict the vapor−liquid and liquid−liquid equilibria of polymer solutions and accurately capture the effects of polymer molecular weight and molecular topology on phase behavior.