Interpretation of dynamic scattering experiments on ternary polymer mixtures

Abstract

The dynamics of a ternary polymer mixture consisting of either homopolymers A and B, or diblock copolymers A-B, in a matrix of homopolymers C, is studied using the random phase approximation and assuming incompressibility. The relaxation frequencies and the amplitudes of the modes in dynamic scattering on such a mixture have been calculated as a function of the wave number q. In addition, the first cumulant of the dynamic scattering function of a labelled component is obtained in all q regions including the high q region where the segmental diffusion dominates the relaxation of the scattering function. The particular mixture consisting of A-B diblock copolymers in a matrix of homopolymers A, studied recently by Stuhn and Rennie, is analysed in detail, by calculating the first cumulant in the entire q region.