Electron beam-induced cationic polymerization drives structure and properties of epoxy coatings

In the quest for sustainable yet high-performing coatings, Electron Beam-initiated cationic polymerizations of epoxy resins can advantageously combine the energy-efficient and highly productive features of EB curing to the desirable mechanical and chemical characteristics of epoxy coatings. Nevertheless, the relatively slow polymerization rate of EB cationic epoxy systems obstructs their widespread use compared to e.g. acrylate-functional resins polymerized by free radical mechanism. In this work, we report the preparation and characterization of a series of EB-cured cationic epoxy polymer coatings. We connect molecular properties (chemical structures of monomers and cationic initiators), curing conditions (EB irradiation parameters) and network characteristics, and show that epoxy coatings with good mechanical properties and no residual unreacted epoxy functionalities can be prepared in very short curing times without the need for thermal post-EBC treatments. Establishing structure–properties relationships in the cationic curing of commercially relevant epoxy resins represents a major first step towards a wider adoption of cationic curing technologies by the coating industry.