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 a dded salt (MgSO4), was investigated using environmental scanning elect ron microscopy. Without added salt, the polymer latices form a hexagon al or cubic packing structure upon evaporation of water from the sampl e, and subsequently the deformation and compaction of the polymer lati ces occurs. The surface of the aggregated polymer latices appears smoo th. With added MgSO4 salt, in general neither a hexagonal nor a cubic packing arrangement is seen as the water evaporates. The packing struc ture is irregular and porous, and the individual polymer latex particl es can always be seen. Moreover, two-dimensional fractal structures we re observed in the aggregated state of the highly salted solution.