Detailed analysis of termination kinetics in radical polymerization

Studies into the termination step of radical polymerization have mostly been carried out via chain-length-averaged properties. With advent pulsed laser (PLP) induced by single pulses (SPs), analysis rate coefficients kt has significantly improved. In conjunction with highly time-resolved near-infrared (NIR) detection monomer consumption, SP-PLP-NIR allows for measurement as a function temperature, pressure and degree conversion. addition suitable reversible addition−fragmentation chain−transfer agent, this technique even determination chain-length-dependent kti,i, where i refers to chain length two terminating radicals identical size. The decay kti,i is more pronounced at small size below crossover ic. At larger lengths, decreases weaker extent. Thus, so-called composite model perfectly suited representing behaviour across entire chain-length range. A further clear improvement provided SP-PLP-EPR method, which directly measures type concentration microsecond electron paramagnetic resonance (EPR) spectroscopy. This EPR-assisted particularly valuable polymerizations secondary undergo backbiting thus types radicals, tertiary, are simultaneously present, case acrylic monomers. © 2023 Authors. Polymer International published John Wiley & Sons Ltd on behalf Society Industrial Chemistry.