Small-molecule ionic liquid-based adhesive with strong room-temperature adhesion promoted by electrostatic interaction

Abstract

Low-molecular-weight adhesives (LMWAs) possess many unique features compared to polymer adhesives. However, fabricating LMWAs with adhesion strengths higher than those of polymeric materials is a significant challenge, mainly because of the relatively weak and unbalanced cohesion and interfacial adhesion. Herein, an ionic liquid (IL)-based adhesive with high adhesion strength is demonstrated by introducing an IL moiety into a Y-shaped molecule replete with hydrogen bonding (H-bonding) interactions. The IL moieties not only destroyed the rigid and ordered H-bonding networks, releasing more free groups to form hydrogen bonds (H-bonds) at the substrate/adhesive interface, but also provided electrostatic interactions that improved the cohesion energy. The synthesized IL-based adhesive, Tri-HT, could directly form thin coatings on various substrates, with high adhesion strengths of up to 12.20 MPa. Advanced adhesives with electrical conductivity, self-healing behavior, and electrically-controlled adhesion could also be fabricated by combining Tri-HT with carbon nanotubes.