Photo-induced controlled radical polymerization of methyl methacrylate mediated by photosensitive nitroxides

Photosensitive nitroxides bearing different chromophore groups (benzophenone, naphthalene and quinoline) were synthesized and characterized. The photochemical properties of the synthesized products were investigated by UV-visible and fluorescence measurements. The results indicated that an efficient energy transfer from the chromophore moiety to the nitroxide radical moiety could occur within the molecular distances. The photo-induced nitroxide-mediated polymerization of methyl methacrylate (MMA) was performed using the photosensitive nitroxide/2,2-dimethoxy-2-phenyl acetophenone as a bimolecular mediated system. The controlled character of the polymerization was confirmed by the linear tendency of molecular weight evolution with narrow molecular weight distribution (1.3-1.4). The experimental conditions, such as type of chromophore, initiator concentration and molar ratio of initiator/nitroxide, are discussed for a better understanding of the mechanism of the controlled polymerization. Using the polymerization products as macroinitiator, the chain extension reaction of MMA turned out to be able to re-initiate further polymerization of the monomer. (c) 2014 Society of Chemical Industry