Determination of Free-Radical Propagation Rate Coefficients for Cycloalkyl and Functional Methacrylates by Pulsed-Laser Polymerization

Abstract

Free-radical propagation rate coefficients (kp) for three cycloalkyl methacrylates and two functional methacrylates were measured at temperatures between 30 and 110 °C. The data were obtained by analyzing molecular weight distributions of polymer produced by pulsed-laser polymerization − the PLP/MWD technique. Arrhenius parameters were compared with recent results reported for linear and branched alkyl methacrylates, including methyl methacrylate (MMA) and n-dodecyl methacrylate (DMA). The highest kp value, for 2-hydroxypropyl methacrylate, is more than twice the MMA value, and is 50% higher than the DMA value at 50 °C. The monomer with the lowest kp value, isobornyl methacrylate, has a coefficient of similar magnitude to DMA. Values for the other three monomers − glycidyl, cyclohexyl, and benzyl methacrylates − are intermediate between these two levels.