Thiol-Vinyl Photopolymerizations: Controlled Network Evolution

Presently, the photopolymerization field is dominated by acrylic systems. Thiol-vinyl photopolymerizations have many advantages over acrylic polymerizations, like reduced oxygen inhibition, initiatorless polymerization, delayed gelation, and greater control over network structure. However, currently there are no theories for predicting and thereby controlling network evolution of these kinetically controlled mixed step-chain thiol-vinyl polymerizations. Here, a combined kinetic and statistical modeling framework is developed to predict network properties including molecular weight, gel point, and crosslinking density. Further, non-mean field kinetic modeling is used to include network non-ideality, cyclization, and ensuing network predictions are successfully contrasted with experiments. Then, network control aspect of these polymerizations is employed to design degradable materials with tunable degradation kinetics that are suitable for controlled drug delivery and tissue engineering. Both the network properties and concomitant degradation kinetics are adjusted by changing thiol functionality or stoichiometric ratio.