Mechanistic aspects of nitroxide-mediated controlled radical polymerization of styrene in miniemulsion, using a water-soluble radical initiator

Nitroxide-mediated controlled free-radical polymerization of styrene was studied in a miniemulsion system. The use of an acyclic beta -phosphonylated nitroxide enabled polymerization to be performed at a temperature below 100 degreesC, typically 90 degreesC. A bicomponent initiating system was chosen, i.e., a radical initiator in conjunction with added free nitroxide. This work focused on the mechanistic understanding of the polymerization. The parameters that affect both the kinetics of polymerization and the control of the molar mass and molar mass distribution have been examined and discussed, such as the nature and concentration of the pH buffer, the initiator concentration, the monomer/water ratio, and the process for chain extension.