DETERMINATION OF FREE-RADICAL PROPAGATION RATE COEFFICIENTS FOR CYCLOALKYL AND FUNCTIONAL METHACRYLATES BY PULSED-LASER POLYMERIZATION

Free-radical propagation rate coefficients (k(p)) for three cycloalkyl methacrylates and two functional methacrylates were measured at tempe ratures between 30 and 110 degrees C. The data were obtained by analyz ing molecular weight distributions of polymer produced by pulsed-laser polymerization - the PLP/MWD technique. Arrhenius parameters were com pared with recent results reported for linear and branched alkyl metha crylates, including methyl methacrylate (MMA) and n-dodecyl methacryla te (DMA). The highest k(p) value, for 2-hydroxypropyl methacrylate, is more than twice the MMA value, and is 50% higher than the DMA value a t 50 degrees C. The monomer with the lowest k(p) value, isobornyl meth acrylate, 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.