Tough bio-based thermosets with dual curing capability via epoxy and allylic functionality

Acrylic monomer from high oleic soybean oil (HO-SBM) was combined with vanillin-derived aromatic counterpart, 2-glycidoxy-5-vinylanisole (GVA), in chain copolymerization to design tough biobased thermosets with a dual-curing capability. Under specified conditions, a polymer network can be formed by selective cross-linking of epoxy groups of GVA or HO-SBM allylic groups as well as dual-curing via epoxy-amine and autoxidation mechanisms simultaneously. Glass transition temperature of the synthesized copolymers increases with the GVA content, although the values fall in a rather narrow range (-10 degrees C to 7 degrees C). Thermosets cured via epoxy-amine and dual-curing have a significantly denser network when compared to autooxidation. Such an increase in cross-link density led to improved chemical (solvent) resistance and hardness of thermoset coatings. At the same time, a higher GVA fraction in the chain (from 37 to 44 wt%) noticeably increases Young's modulus of thermosets (up to 235 MPa). A substantial modulus increase at the rubbery plateau was observed for epoxy-amine and dual-curing thermosets with 44 wt% of GVA.