Ultrastrong and Versatile Nonisocyanate Polyurethane Adhesive under Extreme Conditions

Abstract

Adhesives with ultrastrong adhesion performance and environmental tolerance under extreme conditions, such as low temperatures or immersion in organic solvents, are of critical need in aerospace, aircraft, energy, and chemical industries but rare. Herein, a solvent-free and highly cross-linked nonisocyanate polyurethane (NIPU) adhesive with ultrastrong interfacial adhesion, superior substrate versatility, and excellent tolerance to extreme conditions is reported. The adhesive is fabricated by a one-step strategy combining sol–gel chemistry and cyclic carbonate–amine polyaddition. The former results in an amine-terminated hyperbranched siloxane, which can promote the polyaddition reaction and enhance the cross-linking density, and the latter yields NIPU with high-density polar groups. The adhesive exhibits an ultrahigh adhesion strength of up to 20.67 MPa ascribed to the tough cohesion and high-density hydrogen bonds established on the interface. Moreover, the adhesive exhibits superior versatility to different substrates, including ceramic, steel, aluminum alloy, copper alloy, poly(methyl methacrylate), polyethylene, glass, and wood. Furthermore, the NIPU adhesive can be cured at low temperatures and exhibits excellent environmental tolerance to extreme conditions including ultralow temperature (−196 °C) and organic solvents. The novel adhesive has promising potential for applications under specific and extreme conditions such as aerospace, aircraft, energy, and chemical industries.