Emulsifier-free polymerization of methyl methacrylate with a carboxyl-containing initiator

It was shown that the emulsifier-free polymerization of methyl methacrylate initiated by 4,4'-azobis(4-cyanovaleric acid) at high initial pH values di ffers from the polymerization of styrene carried out under analogous condit ions. It was demonstrated that the hydrolysis of the monomer in an alkaline medium with the formation of methacrylic acid leads to a decrease in the r ate of polymerization and to a reduction in the diameter of microspheres; n evertheless, the extent of carboxylation of the particle surface drops as p H increases. Varying the initial pH value enables one to control the diamet er of the monodisperse microspheres of PMAA in a submicron range.