Dynamic scattering from ternary mixtures of polymers in solution

Abstract

The dynamic scattering properties of ternary mixtures made up of two polymer components and a solvent are considered. Examples of symmetrical and nonsymmetrical mixtures are examined. Particular attention is focused on the interpretation of the eigenmodes. It was recently shown that the eigenmodes for ternary mixtures could be rigorously identified with the cooperative and interdiffusive modes only if the two polymer components are identical, except for their optical properties. Here, we consider several mixtures made up of different polymer constituents and compare the variations of the relaxation frequencies with the scattering wave vector q. In all the examples considered, the behavior of (Γ, Γ T) and (Γ′, Γ 1) are found to be qualitatively the same. This leads to the conclusion that, although the eigenmodes can be identified rigorously as the cooperative and interdiffusive dynamical processes only for symmetrical mixtures with a finite χ-parameter, they can still be so-identified approximately even in the case of different polymers and nonsymmetrical mixtures under certain experimental conditions.Key wordsDynamic scatteringternary mixturescooperative modeinter-diffusive mode