Phase Equilibria of Quasi-Ternary Systems Consisting of Multicomponent Polymers in a Binary Solvent Mixture III. Effects of Average Molecular Weight and Molecular Weight Distribution of the Original Polymer

Abstract

The effects of average molecular weight and molecular weight distribution MWD of the original polymer on the phase equilibrium of quasi-ternary systems consisting of multicomponent polymers, solvent 1 and solvent 2 were studied by computer experiments. For this purpose, polymers having strict monodispersity, Poisson (the weight-average molar volume ratio of the polymer to the solvents, Xw=300), Schulz–Zimm (Xw=150—6000, the ratio of the Xw to number-average molar volume ratio of the polymer to the solvents, Xw/Xn=1.03—5.0), and Wesslau (Xw=300, Xw/Xn=2.0—8.0) type molecular weight distributions were utilized. A small, but significant difference was observed for coexistence curves and other characteristic parameters between strictly monodisperse polymer and the Schulz–Zimm polymer (Xw/Xn=1.03). As Xw of the original polymer, Xwo, decreases, the partition coefficient σ, phase volume ratio R, and the polymer volume fraction in a polymer-rich phase vp(2) increases, and the MWD of the polymers in both phases becomes sharp. As Xw/Xn of the original polymer (Xwo/Xwo) decreases, σ, R, and vp(2) increase for a small relative amount of polymer in a polymer-rich phase ρp, but in larger ρp region, σ, R, and vp(2) decrease with Xwo/Xwo.