Effect of seed characteristics on morphology development in poly(n-butyl acrylate)-poly(n-butyl methacrylate) core-shell dispersions

This article reports on the influence of synthesis characteristics such as seed cross linking, particle-size distribution (PSD), and surfactant in the seeded emulsion polymerization of n-butyl acrylate-butyl methacrylate core-shell systems. These systems were studied using a combination of techniques such as light scattering (static and dynamic), asymmetric field flow fractionation coupled with multiangle laser light scattering and transmission electron microscopy. Complimentary data, obtained from static light scattering and electron microscopy studies, on the effect of seed crosslinking on morphology development reveals that the presence of a crosslinked seed favors the formation of nonequilibrium core-shell morphology. For uncrosslinked seeds occluded structures were present with a diffuse boundary between the core and the shell. In both cases, i.e., with or without surfactant, a monomodal PSD was observed for the core-shell systems and the relative size polydispersity and the shape of the seed PSD were retained. Use of surfactant was found to broaden the PSD but did not seem to affect the formation core-shell morphology. The study also shows the influence of crosslinked seeds on the film properties. Copyright © 2012 Wiley Periodicals, Inc.