Macromolecules, Vol.27, No.3, 650-655, 1994
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.
Keywords:FREE-RADICAL POLYMERIZATION;CHAIN CROSSLINKING PHOTOPOLYMERIZATION;CONTROLLED VINYL POLYMERIZATION;ELECTRON-SPIN RESONANCE;METHYL-METHACRYLATE;RATE COEFFICIENTS;HIGH CONVERSION;EMULSION POLYMERIZATION;VOLUME RELAXATION;NETWORK FORMATION