II. Fundamentals of Free-Radical Polymerization Propagation Kinetics in Radical PolymerizationStudied via Pulsed Laser Techniques

摘要

Pulsed laser techniques have enormously improved the quality by whichrate coefficients of radical polymerization may be determined. The specific and mostimportant feature of the various types of pulsed laser techniques consists in thealmost instantaneous production of a significant radical concentration and in theease by which radical concentration may be controlled by applying further laserpulses at pre-selected delay times. The pulsed laser polymerization – size exclusionchromatography (PLP-SEC) experiment is extremely valuable for the determination ofreliable propagation rate coefficients, kp. The present article briefly reviews recentresults from PLP-SEC studies directed toward the solvent dependence of k_pin aqueoussystems, into k_pin copolymerization reactions, and into measurements of propa-gation rate coefficients in systems containing two types of radicals, as is the casewith acrylates, where secondary chain-end radicals may undergo 1,5-H shift reactions(backbiting steps) to produce tertiary midchain radicals. By a propagation step, thetertiary radicals are transformed back to secondary ones.