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 CO2) 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).