Solvent Influence on Propagation Kinetics in Radical Polymerizations Studied by Pulsed Laser Initiated Polymerizations

The influence of the reaction medium (organic solvents, water, ionic liquids, supercritical CO(2) ) on the propagation rate in radical polymerizations has very different causes, e.g., hindered rotational modes, hydrogen bonding or electron pair donor/acceptor interactions. Depending on the origin of the solvent influence propagation rate coefficients, k(p) , may be enhanced by up to an order of magnitude associated with changes in the pre-exponential or the activation energy of k(p) . In contrast, non-specific interactions, size and steric effects lead to rather small changes in the vicinity of the radical chain end and are reflected by modest variations in k(p) .