Electron Spin Resonance (ESR) Observation of Radical Migration Reactions in the Polymerization of Alkyl Acrylates

Abstract

Electron Spin Resonance (ESR) spectroscopic studies directed at clarifying the fundamentals of radical polymerizations have been conducted. A combination of ESR and atom transfer radical polymerization (ATRP) provided significant new information on the reactivity and dynamics of propagating radicals in radical polymerizations. Moreover, chain lengths of the radicals can be differentiated by the combined method. Previously, it had been extremely difficult, even impossible, to obtain such information from ESR spectra during conventional radical polymerizations. To overcome this difficulty radical precursors of oligo- and poly(meth)acrylates were prepared by ATRP. The mechanisms of main chain transfer reactions have been investigated and the possibility of another chain transfer reaction, to ester side groups, was examined. Multi-step radical migration behavior in various alky acrylates was also investigated and experimental evidence for such chain transfer reactions will be shown in this paper.