Propagation Kinetics of Methacrylic Acid Studied by Pulsed-Laser Polymerization

Propagation rate coefficients k p have been determined for free radical polymerizations of methacrylic acid (MAA) using pulsed-laser polymerizations (PLP) combined with size exclusion chromatography (SEC). The temperature dependence of k p has been studied for polymerizations of 33 vol % monomer in methanol in the temperature range from 20 to 60 °C. k p is described by the following Arrhenius relation: ln[ k p /L·mol -1 ·s -1 ] = (13.31 ± 0.49) − (2132 ± 133) K / T . Variations in MAA concentration and the type of solvent do not influence k p significantly. Any distinctions elicited in k p by these variations are of the order of the experimental uncertainty and are much smaller than the relative changes in the MAA monomer−dimer equilibrium observed by FTIR spectroscopy. The magnitude of k p and its variation with temperature are similar to results reported for methyl methacrylate and the rest of the methacrylate family.