Impact of hydrogen bonding on propagation kinetics in butyl methacrylate radical polymerizations

Abstract

Pulsed laser initiated polymerizations of butyl methacrylate in butanol show a significant enhancement of the propagation rate coefficient k(p) compared to polymerizations in bulk. The activation energy E-A of k(p) is reduced due to the presence of butanol: at a monomer concentration of 0.8 mol.L-1 k(p) for polymerizations in butanol at 0degreesC is about 85% higher than in bulk, the difference reduces to 44% at 80degreesC. These findings are associated with a reduction in E-A of k(p) from 23.0 kJ.mol(-1) for bulk systems to 20.5 kJ.mol(-1) for polymerizations in butanol. The increase of k(p) in the presence of an alcohol is explained by the formation of hydrogen bonds between the OH group of the solvent and the carbonyl group of the monomer.