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

Abstract

Propagation rate coefficients (k p ) 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. k p values for CHMA and GMA agree within the experimental accuracy of ± 20 per cent. They are by about a factor of 2.5 below k p of HEMA. The activation energies and activation volumes of k p of methacrylates studied so far, including linear and branched alkyl methacrylates, are close to each other: E A (k p ) = (22 ± 2) kJ.mol -1 and ΔV ( k p ) = - (16 ± 2) cm 3 . mol -1 , respectively, indicating a pronounced family-type behavior.