Interpretation of reactivity in radical polymerization - radicals, monomers, and transfer agents: Beyond the Q-e scheme

50 years ago, Alfrey and Price advanced the e-e scheme for the interpretati on of radical and monomer reactivity and the prediction of monomer reactivi ty ratios in radical copolymerization. Despite the early criticism of the s cheme by Mayo and Walling, and its obvious fundamental shortcomings, it con tinues to be essentially the only such scheme in use today. However, the mo re soundly based Patterns of Reactivity Scheme, originally proposed in 1959 , has recently been revised in such a way that it provides, in a simple way , far more accurate predictions of monomer reactivity ratios than does the e-e scheme. Moreover, it is equally applicable to the forecasting of chain- transfer constants and to the understanding of the reactivity of initiator radicals. The history of investigations of radical, monomer, and transfer a gent reactivity is reviewed here, including a summary of the Revised Patter ns Scheme and its applications. (C) 1999 John Wiley & Sons, Inc.