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The controlled/“living” radical polymerization of n-butyl methacrylate was conducted in an emulsion under reverse atom transfer radical polymerization (ATRP) conditions. The initiators used were conventional water-soluble initiators, such as potassium persulfate (KPS), 2,2‘-azobis(2-methylpropionamidine) dihydrochloride (V-50), and 2,2‘-azobis[2-(2-dimidazolin-2-yl)propane] dihydrochloride (VA-044). The transition metal catalyst employed was copper(II) dibromide with 4,4‘-dialkyl-2,2‘-bipyridine as the ligands.

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Reverse atom transfer radical polymerization (ATRP) of n-butyl methacrylate was conducted in an aqueous dispersed system. Using a water-soluble initiator (V-50), a nonionic surfactant (Brij 98), and a hydrophobic ligand (dNbpy) to complex a copper halide, polymers with relatively well controlled molar masses and low polydispersities were obtained. Stable latexes with particle diameters within 150−300 nm were formed. Kinetic studies were performed under various experimental conditions. The influence of the concentrations of the catalyst, the surfactant, and the initiator as well as the temperature on the polymerization rate, molecular weight, and particle size was investigated. Because of the lack of high molecular weight polymer during the early polymerization stage, reverse ATRP in the aqueous dispersed system presumably has a different “nucleation” mechanism from that of a conventional emulsion polymerization. In addition, fast decomposition of the initiator prevents the continuous entry of radicals into the particles from the aqueous phase. As a result, the kinetics of the reverse ATRP is fundamentally different from a classical emulsion polymerization and is controlled mainly by the atom transfer equilibrium.