A Repeatable Supramolecular Adhesive with Ultrastrong Underwater Adhesion, Self-Healing Ability, and Long-Term Stability

Repeatable adhesives attract enormous attention for their environmental friendliness and adaptability but suffer from weak adhesion when used in underwater conditions. Herein, we develop a supramolecular adhesive by incorporating quadruple hydrogen-bonded units into isocyanate-modified polydimethylsiloxane (PDMS) polymers. By synergistically utilizing interfacial covalent bonds and multiple hydrogen bonds, the supramolecular adhesive exhibits repeatable adhesion in air for at least 5 cycles and ultrastrong underwater adhesion of ∼9.37 MPa. The rapid establishment of covalent bonds on various substrate surfaces confers the adhesive with instantaneous and tough adhesion in both air and underwater environments. Reversible multiple hydrogen bonds within the adhesive polymers endow the material with self-healing performance. In addition, rheology analysis combined with mechanical tests revealed the thermal-responsive property of the adhesive. Taking advantage of the self-healing performance and thermal-responsive adhesion, the adhesive exhibits repeatable ability. This work deepens the understanding of multiple hydrogen bonds and isocyanate-modified PDMS polymers, enabling the fabrication of repeatable adhesives for industrial applications.