Polarized and depolarized dynamic light scattering from a block copolymer melt

Abstract

Dynamic light scattering measurements on a symmetric poly(ethylenepropylene-b-dimethylsiloxane) block copolymer reveal three polarized (VV) and one depolarized (VH) modes. The VV modes correspond to cluster diffusion, the heterogeneity mode and a diffusive mode that is tentatively ascribed to adventitious homopolymer. The VH mode is attributed to the reorientational dynamics of the pretransitional composition fluctuations. Furthermore, it is shown that in the ordered state the copolymer is a sufficiently depolarizing medium that VH-inactive modes can appear clearly in the VH scattering geometry