Controlled radical polymerization of 2-hydroxyethyl methacrylate initiated by photofunctional 2-(N,N-diethyidithiocarbamyl)isobutyric acid

We demonstrated that density functional theory calculations provide a reliable and quantitative prediction of the trends in C-S bond dissociation energies using several model compounds as photoinitiator. On the basis of this information, we designed a possible photofunctional initiator for the polymerization of hydrophilic vinyl monomers. Photopolymerization of 2-hydroxyethyl methacrylate (HEMA) hydrophilic monomer was carried out in ethanol initiated by 2-(N,N-diethyldithiocarbamyl)isobutyric acid (DTCA) under UV irradiation. We performed the first-order time-conversion plots in this polymerization system, and the straight line in the semilogarithmic coordinates indicated first order in monomer. The molecular weight of the poly(2-hydroxyethyl methacrylate) (PHEMA) increased with increasing conversion. The molecular weight distribution (M-w/M-n) of the PHEMA was about 1.5. Methyl methacrylate (MMA) could also be polymerized in a living fashion with such a PHEMA precursor as a macroinitiator because PHEMA exhibited a dithiocarbamate (DC) group at its terminal end. This system could be applied to the architecture of amphiphilic block copolymers. It was concluded that these polymerization systems proceeded with controlled radical mechanism. (C) 2003 Wiley Periodicals, Inc.