Interfacial Tension of Demixed Polymer Solutions

摘要

The interfacial tension of demixed polymer solutions is an important topic because an accurate description of this phenomenon is the first step toward a description of spinodal decomposition in polymer solutions. DeGennes has argued that the interfacial thickness of demixed polymer solutions equals the correlation length in the most concentrated phase. Therefore, a mean field description could not be expected to work. For example, the mean field theory of Roe predicts interfaces much broader than the correlation length and subsequently predicts interfacial tensions smaller than observed by over 100%. In this paper we attempt to make DeGennes' prediction quantitative. This is accomplished by using the ''Gibb's adsorption isotherm'' which relates interfacial tension to polymer adsorption and chemical potential. The latter is obtained from an empirical Flory-Huggins fit to equilibrium phase diagrams. The predictions of interfacial tension are quantitative, with an accuracy comparable to that of the empirical fit of the phase diagrams. 12 refs., 2 figs. (ERA citation 11:020577)