Living free radical polymerizations mediated by the reversible combination of transient propagating and persistent nitroxide radicals. the role of hydroxylamine and alkene formation

A kinetic analysis of living polymerizations controlled by persistent nitroxide radicals is extended to cover the formation of hydroxylamines and alkene macromonomers. This reaction can occur by radical disproportionation during the cross-reaction of the carbon-centered propagating and the nitroxide radicals and/or by a direct fragmentation of the dormant alkoxyamines. For equal extents, both pathways cause nearly indistinguishable upper limits of the monomer conversion and a very similar increase of the polydispersity in the final stages of polymerization, but they do not markedly affect the linear increase of the degree of polymerization with conversion.