Growth of Grains and Correlated Grain Clusters in a Block Copolymer Melt

Ordering kinetics after quenching a block copolymer melt from the disordered state to the ordered state were studied by time-resolved, depolarized light scattering. A theoretical framework for relating the scattering patterns to the granular organization within the sample was developed. In some cases we found that ordering proceeds by the growth of individual grains. These systems were characterized by scattering profiles that are monotonic functions of scattering angle. In contrast, the scattering profiles, under certain quench conditions, contained peaks indicating the presence of intergrain correlations. We demonstrate that these correlations arise due to the presence of three-dimensional grain clusters. Estimates of the size, shape, and concentration of grains during the transformation from disorder to order were obtained. In the early stages of ordering, the grains grew quickly at the expense of the disordered phase until the entire sample was occupied by grains. This stage was followed by extremely slow grain growth (or undetectable growth, in the case of large quench depths) due to defect annihilation.