Critical evaluation of rate parameters for chain-length-dependent termination of styrene and n-alkyl methacrylates, leading to the provision of benchmark data for such; and guidelines on the correct employment of these parameters for evaluation of (steady-state) rate and average degree of polymerization.
The previous project in this series, “Critically evaluated termination rate coefficients for free-radical polymerization. 1. Current status, evaluation of experimental methods, data for styrene and methyl methacrylate” (project 2000-028-1-400), was by any measure a success. This message is conveyed most emphatically by the impressive number of citations so far for the two publications from this project: 108 for M. Buback et al. Macromol. Chem. Phys. 2002, 203, 2570-2582 (https://dx.doi.org/10.1002/macp.200290041), and 72 for C. Barner-Kowollik et al. Prog. Polym. Sci. 2005, 30, 605-643 (https://dx.doi.org/10.1016/j.progpolymsci.2005.02.001).
What these figures evidence is the thirst of the radical polymerization (RP) community – including the many practitioners of reversible-deactivation (“living/controlled”) RP – for definitive instruction and data on termination, traditionally the most difficult topic in the realm of RP kinetics. The reason for the difficulty has become incontrovertibly clear over the last decade: termination is chain-length dependent in rate.
Nov 2014 – Project announcement published in Chem. Int. Nov-Dec 2014, p. 20; DOI: 10.1515/ci-2014-0615
July 2020 update – Final data from the Buback laboratory will soon be available for this project, as will work from the closely related project 2013-047-1-400 “Critically evaluated rate coefficients for radical polymerizations of styrene”. Current theoretical work from Nikitin on the SP PLP EPR method is also being considered for impact on existing termination data.
Last update 25 July 2020