Macroradical reactivity studied by electron spin resonance

Abstract

In this work data are reviewed on direct measurments of radical reaction kinetics in polymers by the EPR method. Published data as well as the authors' results are given on the kinetics of the reactions of macroradical decay, macroradical oxidation, hydrogen elimination and monomer addition to macroradicals.As an explanation of the process of macroradical decay the mechanism of radical state migration by means of hydrogen atoms elimination from adjacent chains has been suggested and confirmed. The activation energies of various macroradical reactions have been measured and found to be very high. This is due to a specifity of the kinetic process in solid phase and to the participation of the diffusion phenomenon. Comparative investigation of the reactivity of various macroradicals reveals a great importance of the steric factor, i. e. the entropy of the transition state for the kinetics of macroradical reactions.