A strain-reinforcing elastomer adhesive with superior adhesive strength and toughness

Abstract

Strong and ductile adhesives often undergo both interfacial and cohesive failure during the debonding process. Herein, we report a rare self-reinforcing polyurethane adhesive that shows the different phenomenon of only interfacial failure yet still exhibiting superior adhesive strength and toughness. It is synthesized by designing a hanging adhesive moiety, hierarchical H-bond moieties, and a crystallizable soft segment into one macromolecular polyurethane. The former hanging adhesive moiety allows the hot-melt adhesive to effectively associate with the target substrate, providing sufficient adhesion energy; the latter hierarchical H-bond moieties and a crystallizable soft segment cooperate to enable the adhesive to undergo large lap-shear deformations through sacrificing weak bonds and mechano-responsive strength through the fundamental mechanism of strain-induced crystallization. As a result, this polyurethane adhesive can keep itself intact during the debonding process while still withstanding a high lap-shear strength and dissipating tremendous stress energy. Its adhesive strength and work of debonding are as high as 11.37 MPa and 10.32 kN m⁻¹, respectively, outperforming most reported tough adhesives. This self-reinforcing adhesive is regarded as a new member of the family of strong and ductile adhesives, which will provide innovative chemical and structural inspirations for future conveniently detachable yet high-performance adhesives.