Propagation and Size-Dependent Chain Termination Rate Parameters in the Polymerization if Acrylates in Aqueous Solution as Studied by Pulse Radiolysis

Abstract

The radiation polymerizations of ethyl acrylate (EA) and hydroxyethyl acrylate (HEA) monomers in aqueous solutions were studied. For pulse radiolytic experiments, optical detection was used to measure the concentration of intermediates. The absorption spectra taken after a 2.6−μs pulse in N₂O-saturated acidic solution of EA and HEA are shown to have maxima at 300 nm. It was proved by comparative measurements that these maxima belong to α-carboxy alkyl radicals. At a low acrylate concentration (below 1 mmol˙dm⁻³) and a relatively high dose/pulse value (above 30 yY), the decay of the transient signal occurs close to second-order kinetics. Average values of the termination rate parameters were calculated from aftereffect measurements. A computer program based on numerical integration was applied in order to estimate the individual rate parameters.