Propagation Kinetics in Radical Polymerization Studied via Pulsed Laser Techniques

Abstract

AbstractPulsed laser techniques have enormously improved the quality by which rate coefficients of radical polymerization may be determined. The specific and most important feature of the various types of pulsed laser techniques consists in the almost instantaneous production of a significant radical concentration and in the ease by which radical concentration may be controlled by applying further laser pulses at pre‐selected delay times. The pulsed laser polymerization – size exclusion chromatography (PLP‐SEC) experiment is extremely valuable for the determination of reliable propagation rate coefficients, kp. The present article briefly reviews recent results from PLP‐SEC studies directed toward the solvent dependence of kp in aqueous systems, into kp in copolymerization reactions, and into measurements of propagation rate coefficients in systems containing two types of radicals, as is the case with acrylates, where secondary chain‐end radicals may undergo 1,5‐H shift reactions (backbiting steps) to produce tertiary midchain radicals. By a propagation step, the tertiary radicals are transformed back to secondary ones.