Thiol-ene adhesives from clove oil derivatives

This paper reports the synthesis of catechol-functionalized thiol-ene polymer networks as photocurable adhesives, where the adhesive interactions are derived from 4-allylpyrocatechol - a monofunctional alkene readily obtained from natural products of Syzygium aromaticum flower buds (clove). The thiol-ene photopolymerization process enables rapid cure times, low energy input, and solvent-free processing. The resulting polymer networks show improved macroscopic adhesion to a variety of substrates - including glass, marble, aluminum, and steel - by varying the concentration of 4-allylpyrocatechol in the network. Additionally, the effects of the catechol moiety on polymerization kinetics, thermomechanical, and mechanical properties were determined by comparing the synthesized catechol moiety to a series of control monomers such as eugenol (one phenol group) and methyl eugenol (no phenol groups).