Underwater self-curing and adhesion of phenolic polymer coacervate with negligible external stimuli

This study introduces a synthetic polymer system that achieves simultaneous underwater self-curing and adhesion without external triggers. Inspired by DNA and mussel adhesion system, chitosan-phloroglucinol (CHI-PhG) is engineered to collocate a cationic donor and a π-acceptor within a single pendant unit. This molecular architecture suppresses intramolecular contacts and instead promotes intermolecular, cation-π-mediated "zipping," which effectively limits polymer diffusion in aqueous media. The resulting reversible assemblies are spatially organized to bring adjacent phloroglucinol (PhG) moieties into proximity, enabling their oxidation-driven conversion into an irreversible phenol-phenol covalent network and thereby effecting spontaneous curing in the absence of light, pH shifts, or thermal cues. In parallel, the coexistence of polyphenol and amine functionalities confers strong underwater adhesion to both organic and inorganic substrates. Collectively, CHI-PhG translates DNA-like interaction encoding and mussel-inspired curing chemistry into a hierarchical assembly-to-curing process, enabling concurrent bulk cohesion and interfacial adhesion in fully aqueous, minimally stimulated conditions.