Fully renewable thermosets based on bis-eugenol prepared by thiol-click chemistry

Thiol-ene photocuring and thiol-epoxy thermal curing have been applied to prepare new thermosets from renewable substrates. As monomers, a tetrallyl and a tetraepoxy derivative of bis-eugenol were prepared by dimerization of eugenol, allylation and further epoxidation. These compounds were reacted with a commercially available tetrathiol, PETMP, and thiols synthesized from two natural resources as squalene (6SH-SQ) and eugenol (3SH-EU) in photoinitiated and thermal conditions. The reaction process was studied by calorimetry, and the materials obtained were characterized by thermogravimetry, thermomechanical studies and mechanical testing. Thiol-epoxy materials showed a better mechanical performance than thiol-ene photocured thermosets. This new epoxy monomer of renewable origin allowed to prepare materials with final properties better than those obtained from the diglycidylether of bisphenol A, owing to the high functionality of bis-eugenol and its rigid and compact structure.