Controlling molecular weight and architecture in free-radical polymerization

The field of free-radical polymerization has been transformed by the development of techniques for controlling the molecular weight and architecture of the resulting polymer. However, to achieve control, these new processes rely upon a delicate balance of the rates of various competing reactions; choosing the optimal control agent for a given system can sometimes be problematic. Over the last decade or so we have been using computational chemistry to study the mechanism of these processes and the effects of substituents on their thermodynamics and kinetics with a view to developing user-friendly guidelines for optimal reagent selection, which we can then apply to the design of optimal control agents. Among our successful computational designs was the first multi-purpose RAFT agent, capable of controlling monomers with disparate reactivities, and a Diels-Alder active RAFT agent suitable for use in the synthesis of self-healing materials. Our current interest is in the development of a new class of pH switchable nitroxides that, in their “on” state, will be capable of functioning at much lower temperatures than currently possible —which promises not only energy savings, but reduced side reactions and a much broader chemical scope than currently possible with this process.

Selected Recent Publications

  • Gryn’ova, G., Lin, C.Y. & Coote, M.L. (2013) Which Side-Reactions Compromise Nitroxide Mediated Polymerization? Polym. Chem., 4, pp. 3744 – 3754
  • Isse, A.A., Gennaro, A., Lin, C.Y., Hodgson, J.L. Coote, M.L. & Guliashvili, T., (2011) Mechanism of Carbon-Halogen Bond Reductive Cleavage in Activated Alkyl Halide Initiators Relevant to Living Radical Polymerization: Theoretical and Experimental Study, J. Am. Chem. Soc., 133, pp. 6254–6264.
  • Lin, C.Y., Marque, S.R.A., Matyjaszewski, K., & Coote, M.L. (2011) Linear-Free Energy Relationships for Modeling Structure-Reactivity Trends in Controlled Radical Polymerization, Macromolecules, 44, pp. 7568–7583


This work was funded by the ARC Centre of Excellence for Free-Radical Chemistry and Biotechnology, and has involved a number of long-standing collaborations but most particularly with Professor Kris Matyjaszewski, Carnegie-Mellon, and Professor Christopher Barner-Kowollik, Karlsruhe Institute of Technology.