Detailed Kinetic and Mechanistic Insight into Radical Polymerization by Spectroscopic Techniques

The in-depth understanding of the kinetics and mechanism of conventional and reversible deactivation radical polymerization (RDRP) strategies requires efficient techniques to attain accurate rate coefficients of the individual reaction steps. Within the recently developed SP-PLP-EPR technique, pulsed-laser polymerization (PLP) induced by a laser single pulse (SP) is carried out in conjunction with highly time resolved EPR detection of the type and the concentration of radicals. The method provides an unrivaled direct access to the measurement of chain-length-dependent termination and also of propagation rate. Even for systems where as a consequence of transfer reactions different types of radical species with distinctly different properties occur, a full kinetic analysis is within reach. The SP-PLP-EPR technique is also applicable toward the measurement of RDRP-related rate coefficients for reversible addition-fragmentation transfer (RAFT) polymerization, atom transfer radical polymerization (ATRP), and organometallic-mediated radical polymerization (OMRP). Investigations into the latter two polymerization strategies benefit from additionally applying UV/vis/NIR in conjunction with Mossbauer spectroscopy to monitor reactions of the metal catalyst.