How Advances in Polymer Characterization Are Enabling a More Rigorous Understanding of Radical Polymerization Kinetics

The advent of reversible-deactivation radical polymerization (RP) has resulted in enormous growth in interest in RP over the last two decades. In the chemical community, this interest has been overwhelmingly focused on synthesis and material properties. However, the marketplace has not yet undergone any sea change, and industrial chemists remain very interested in traditional RP kinetics. As it so happens, major advances in this domain have also occurred. Two recent of these will be outlined in this talk: (1) The characterization of product polymer by large-molecule mass spectrometry (MS) as a window onto the kinetics of chain formation. Such information is yielded by the relative peak heights of the specifically identified products from the various avenues of dead-chain formation. By way of example, new and (for the first time) rigorous results for the disproportionation-to-combination ratio will be presented. (2) The coupling of pulsed-laser polymerization with EPR spectroscopy – the so-called SP PLP EPR technique – to study chain-length-dependent termination (CLDT), which it is now realized is the key to understanding many RP kinetic phenomena. By way of example, results for (meth)acrylate (macro)monomers will be presented. Combining these two strands, it will be shown that MS may be used to study CLDT, as exemplified for methyl methacrylate. Knowledge of the kind furnished by these studies is essential for robust modeling and rigorous understanding of such polymerizations, an obligatory aspect of the design and uptake of advanced materials