Kinetics of Primary Cyclization Reactions in Cross-Linked Polymers: An Analytical and Numerical Approach to Heterogeneity in Network Formation

Abstract

It is difficult to characterize the kinetics of cyclization reactions during free radical photopolymerization of multivinyl monomers because of the varying pendant double bond reactivities and inhomogeneities in the system. Primary cyclization, where a pendant double bond reacts intramolecularly with the propagating active center that formed it, leads to formation of microgels in the network. A new analytical and numerical approach is presented that solves the differential kinetic equations and can be used to investigate the factors influencing cyclization versus cross-linking reactions. Data are presented comparing two approaches, one based on numerical integration of the appropriate balances and one based on an analytical solution.