Self-Healing and Reversible Supramolecular Adhesive Gel with Low-Temperature Resistance.

Adhesive, self-healing, stretchable materials are appealing in emerging scientific and industrial applications. Herein, poly(vinyl alcohol) (PVA)/chitosan (CS)/prenucleation metal-organic framework clusters (preMOFs) hydrogels with boric acid (BA) as cross-linkers, denoted as PSBM gels (PSBM refers to PSB-preMOF-74-Ni, preMOF-74-Ni refers to amorphous prenucleation MOF-74-Ni clusters), were constructed. The strategy for synthesizing a triple-networked supramolecular hydrogel involved introducing dynamic covalent bonds via borate esters within PVA, CS, and prenucleation metal-organic framework clusters, thereby increasing the cross-linking density and mechanical strength. PSBM gels exhibited extreme stretchability (up to 300 times their original length), instantaneous self-healing capability (within 5 s), increased conductivity, reusability, and inherent adhesion. The dehydrated and cured PSBM gel (CPSBM) demonstrated reversible adhesion, maintaining its effectiveness under mild to harsh conditions, including high heat at 200 °C and cryogenic conditions in liquid nitrogen. This research establishes a foundation for the development of hydrogels with self-healing and stretchable abilities, presenting a new strategy for advancing adhesive materials.