Catechol containing polyhydroxyurethanes as high-performance coatings and adhesives

Green routes for the synthesis of high-performance isocyanate-free polyurethane coatings and adhesives are intensively searched for. In this article, we report a solvent- and isocyanate-free formulation for novel poly(hydroxyurethane) glues bearing strongly adherent catechol groups. These adhesives are prepared by the polyaddition of a CO2-sourced tricyclic carbonate, hexamethylene diamine, and a catecholamine (dopamine). The role of the catechol functions on the PHU curing and on the final PHU properties are investigated. Although the dopamine slows down the curing of the formulation, this catecholamine added at only 3.9 mol % impressively improves the mechanical and adhesion performances of PHU. The lap shear adhesion of our product surpasses those of PHU that do not contain the catechols. We also demonstrate that the catechol-bearing PHU glues are competing with the adhesion performances of commercial PU glues, at least when a thermal curing is implemented to overcome the low reactivity of cyclic carbonate with amines. The use of renewable feedstocks, the solvent-free process, the atom economy polyaddition reaction, and the absence of any toxic reagent benefit the sustainability of the final product.