Features of a Dual-Curing Strategy for Making Highly Biobased Thermosets from Plant-Derived Ingredients

This study elaborates on a dual-curing strategy for synthesizing biobased thermosetting polymers from vanillin-derived 2-glycidoxy-5-vinylanisole (GVA) and a soybean oil-based acrylic monomer (SBM). While macromolecular fragments from SBM enriched in polyunsaturated (linoleic and linolenic) fatty acid undergo oxidative cross-linking, the epoxy groups of GVA constituents are simultaneously cured using a biobased amine curing agent. The results reveal a synergy between epoxy-amine and oxidative curing. Dual-cured thermosets exhibit a higher cross-link density than those cross-linked by either curing route alone. This results in an increased material stiffness and Young’s and storage modulus values reaching up to 1240 and 3030 MPa, respectively. This synergy between the two cross-linking mechanisms enables a reduction in the amount of amine curing agent required for efficient network formation. Systematic stoichiometric variation demonstrates that the best-performing biobased thermosets in this study can be formulated at a 1:0.8 epoxy:amine ratio (highest storage modulus). The advantages of the dual-curing strategy for making biobased thermosetting polymers were further highlighted by the thermoset coatings’ characteristics, improved chemical (solvent) resistance, and adhesion to the metal substrate.