A Robust Salty Water Adhesive by Counterion Exchange Induced Coacervate.

Counterion exchange of charged macromolecules has comprehensive implications in biological and synthetic systems such as protein function, biosignaling, ion conducting, and separation, but the correlation between the dynamic ion exchange, polyelectrolyte phase separation, and functionality remains elusive. Here, counterion exchange is exploited as a means to facilitate liquid-liquid phase separation and coacervates featuring higher stability and versatility compared with conventional complex coacervate. Self-coacervation of a cationic polyelectrolyte (polyamidoamine-epichlorohydrin, PAE-Cl) occurs in broader conditions when its original counter anion (Cl- ) is exchanged by bis(trifluoromethane-sulphonyl)imide anion (TFSI- ), as a result of TFSI- counter anions association instead of polyelectrolyte complexation. This coacervate is catechol-free, easy to prepare, and highlights robust wet adhesion strength on diverse submerged surfaces in salty water (pH = 3-11), as demonstrated by its versatile capability of in situ underwater gluing and repairing without any pre-immersive drying.