Insights on Chemical Reactions and Formation Process of Electron Beam-Cured Acrylic Networks

In electron beam (EB) curing of cross-linked acrylic networks, the very high energies in play lead to several chemical phenomena unfolding sequentially and simultaneously. Hence, the formation and composition of cross-linked acrylic networks cured by EB irradiation are expected to be different compared to networks obtained by other curing methods. Herein, we characterize the distinct EB-triggered chemical reactions of a model aromatic epoxy diacrylate by analyzing the cross-linked films cured at different EB process parameters, i.e., EB curing dose and dose rate. The viscoelastic properties of the cross-linked films were evaluated by DMTA, and their respective sol/gel fractions were analyzed by SEC, H-1 NMR, and MS. The cross-linked films differ in their viscoelastic properties and network composition. High EB irradiation parameters were found to trigger multiple chemical reactions, namely, the activation and cleavage of C-C bonds of isopropylidene groups and C-O bonds of hydroxyl, ether, and ester groups. Understanding the connection between EB curing conditions, reactions involved in the network creation and polymer properties can enable bottom-up approaches to material design and a more efficient use of the EB technology on multiple polymer chemistries.