Free-radical propagation rate coefficients for cyclohexyl methacrylate, glycidyl methacrylate and 2-hydroxyethyl methacrylate homopolymerizations

Abstract

Propagation rate coefficients (kp) for the homopolymerization of cyclohexyl methacrylate (CHMA), glycidyl methacrylate (GMA) and 2-hydroxyethyl methacrylate (HEMA) were determined by the pulsed laser polymerization (PLP)/size-exclusion chromatography (SEC) technique. Temperature was varied between -10 and 90°C and pressure up to 2500 bar. kp values for CHMA and GMA agree within the experimental accuracy of ±20 per cent. They are by about a factor of 2.5 below kp of HEMA. The activation energies and activation volumes of kp of methacrylates studied so far, including linear and branched alkyl methacrylates, are close to each other: EA(kp) = (22 ± 2) kJ · mol-1 and ΔV≠(kp) = - (16 ± 2) cm3 · mol-1, respectively, indicating a pronounced family-type behavior.