Morphology of core-shell polymer latices during drying

The morphology of core shell polymer latices (PMMA-rubber-PMMA) (PMMA, poly(methyl methacrylate)) aggregated upon drying, with and without added salt (MgSO4), was investigated using environmental scanning electron microscopy. Without added salt, the polymer latices form a hexagonal or cubic packing structure upon evaporation of water from the sample, and subsequently the deformation and compaction of the polymer latices occurs. The surface of the aggregated polymer latices appears smooth. With added MgSO4 salt, in general neither a hexagonal nor a cubic packing arrangement is seen as the water evaporates. The packing structure is irregular and porous, and the individual polymer latex particles can always be seen. Moreover, two-dimensional fractal structures were observed in the aggregated state of the highly salted solution.