An instant, repeatable and universal supramolecular adhesive based on natural small molecules for dry/wet environments

Development of supramolecular adhesion systems from small molecules is a promising strategy to construct adhesives integrating synthetic simplification and sophisticated properties. Here, we report a facile and green one-pot strategy for fabricating a solvent-free and dynamic supramolecular adhesive via co-heating three readily available feedstocks, a natural small biological molecule (α-lipoic acid), a natural plant polyphenol (tannic acid), and ferric chloride. The adhesive is injectable and self-healing, which can work instantly and repeatedly on various materials (e.g., polytetrafluoroethylene (PTFE)) in diverse conditions (dry, underwater, pH < 7, various ionic environments, and even in vacuum) at room temperature, showing promising applicability in complex environments. The self-strengthening of the supramolecular network with time further improves the adhesion strength of the adhesive for the glass (from about 22 kPa to exceeded 300 kPa after 28 d). More importantly, the adhesive exhibits great potentials to be applied in biomedical fields with wet environments. This ready-to-use and high-performance supramolecular adhesive, constructed by natural small molecules via an extremely facile preparation method, represents a promising universal strategy for both dry and wet adhesion.