KINETIC EVIDENCE OF REACTION-DIFFUSION DURING THE POLYMERIZATION OF MULTI(METH)ACRYLATE MONOMERS

The polymerization behavior and reaction kinetics for a series of multifunctional (meth)acrylate monomers were experimentally characterized and modeled with particular attention focused on the importance of the reaction diffusion mechanism in these polymerizations. In general, reaction diffusion was : found to be the primary mechanism for termination beginning as low as 5% double-bond conversion. Termination mechanisms in linear systems have been found to become reaction diffusion controlled, but not until much higher conversions, 40-50%. Evidence of reaction diffusion included a significant plateau in the termination kinetic constant and strict proportionality of k(p) and k(t) at higher conversion (>10%) for all monomers studied. The ratio of k(t) to k(p) was found to be a single constant for all multiacrylates, independent of the number of acrylate groups. A model that was previously developed by the authors for predicting cross-linking reaction behavior was tested using this experimental data. The kinetic constants for termination and propagation that were experimentally determined provided a method for quantifying the theoretical model parameters associated with reaction diffusion.