Growth processes of poly methylmethacrylate particles investigated by atomic force microscopy

The growth processes of poly methylmethacrylate (PMMA) particles prepared by soap-free emulsion polymerization at a reaction temperature 70°C are observed using scanning electron microscopy and atomic force microscopy to clarify the growth mechanisms at the molecular scale. Here, the use of a cationic initiator, V-50, enables us to synthesize positively charged PMMA, which then adsorbs electrostatically on the negatively charged mica plate with molecular scale smoothness. As a result, the following results are found. If the monomer concentration is high, PMMA particle size increases with increasing initiator concentration, otherwise particle size decreases with increasing initiator concentration. In the former case, the growth mechanism is very similar to that of the polystyrene particles we proposed; in the latter case, the phenomenon is thought to follow the LaMer diagram.