Catherine L. Moad

Initiating free radical polymerization

The kinetics and mechanism of the initiation and reinitiation of free radical polymerization is reviewed. The importance of understanding the kinetics, specificity and efficiency of initiation and chain transfer when predicting polymerization kinetics and polymer composition is highlighted. These factors are particularly important when making low molecular weight polymers and in living or controlled polymerization processes. Examples of RAFT polymerization and catalytic chain transfer are provided.

Quantitative characterization of radiation degradation in polymers by evaluation of scission and cross-linking yields

Abstract This article presents a survey of literature on the quantitative characterization of the radiation degradation of polymers in terms of scission and cross-linking. An outline of the theoretical expressions for such characterization is followed by a general discussion of ways in which those equations may be used to quantify radiation chemical yields of scission, G ( S ), and crosslinking, G ( X ). Specific considerations of their practical application begin with the classical Charlesby-Pinner treatment of solubility measurements on extensively degraded polymers, and then switch to characterization by means of solution studies of polymer samples subjected to much lower radiation doses. Included in those discussions is the evaluation of G ( S ) and G ( X ) by quantifying the effect of irradiation on molecular size distributions inferred from sedimentation velocity, gel permeation chromatography and dynamic light scattering measurements, and also their evaluation from the dose dependence of average molecular weights determined by osmometry, classical light scattering, sedimentation equilibrium and gel permeation chromatography.