Coexistence in a Binary Isotopic Polymer Mixture

Abstract

We have measured directly the phase coexistence characteristics in a high-molecular-weight binary isotopic polymer mixture over a range of temperatures around the critical point, using nuclear-reaction analysis. Our results reveal an equilibrium phase diagram with an upper critical solution temperature, in fair quantitative accord with the simplest form of the Flory-Huggins mean-field model. Deviations may be due to a mild compositional dependence of the monomeric interaction parameter.