Simulation of non-linear free-radical polymerization using a percolation kinetic gelation model

A new kinetic gelation model that incorporates the kinetics of representative non-linear free-radical polymerization is presented. Specifically, free-radical homopolymerization, polymerization in the presence of a chain-transfer agent (CTA, CTA-induced polymerization), and copolymerization of a mixture of the bi- and tetrafunctional monomer is used to simulate kinetic effects on polymerization statistics and microstructures. An algorithm for random next-step selection in a self-avoiding random walk and efficient mechanisms of a component's mobility are introduced to improve the generality of the predictions by removing commonly occurring deficiencies due to early trapping of radicals. The model has the capability to take into account into several free-radical polymerization mechanisms such as crosslinking, branching, and transfer reaction, and also to predict the onset of the sol-gel transition, and the effect of chemical composition on the transition point. It is shown that a better understanding of microstructure evolution during polymerization and chemical gelation is attained. Lastly, one important benefit of the model is to simulate very highly packed random chains or microgels within a polymer network.