The development of an Epoxy-amine/Thiol-ene photocurable system

In this study is reported a new method to photocure epoxy resins rapid and quantitatively. It was combined the thiol-ene photopolymerization with the anionic polymerization of an epoxy resin. A tetrallylic tertiary diamine was used as the curing agent. The basic character of the diamine initiated the anionic polymerization of the epoxy resin and at the same time, the allylic groups of the curing agent reacted with a multifunctional thiol. It was found that increasing the concentration of the thiol-ene system in the epoxy formulation resulted in a higher photopolymerization rate and conversion of the epoxy groups. The moduli of the polymers with increasing concentrations of the thiol-ene system were higher than the modulus of a polymer cured with diethylenetriamine which is a conventional curing agent. A study with model compounds revealed that tertiary amine and multifunctional thiol, as well as the polythioethers formed in the thiol-ene reaction induced the anionic polymerization of the epoxy resin.