The prediction of reactivity in radical polymerisation

Abstract

Until recently, the only method available for the prediction of monomer reactivity ratios in radical polymerisation was the Alfrey-Price Q-e Scheme. This has now been adapted in such a way that all the scheme's undesirable features have been removed and no assumptions are involved other than the basic separation of reactivity into thermodynamic and polar components. It is then found that, provided that the copolymerisation behaviour of any given monomer with (i) styrene and (ii) acrylonitrile has been characterised, its copolymerisation with any other monomer, similarly characterised, can be predicted with much greater precision than hitherto. This procedure is called the Revised Patterns of Reactivity Scheme, or “Patterns”. Unlike the Q-e Scheme, a parallel procedure can be applied to the prediction of transfer constants, with remarkable accuracy over a spread of transfer constant values of nine orders of magnitude. The procedure can also be applied to evaluate the reactivity of initiator radicals with monomers. A side-product of the Patterns scheme is a simple method for obtaining approximate values of the Hammett σ constant for the substituent present on the α-carbon atom of a monomer.