A Mussel-Inspired Design for Robust Catechol-Functionalized Cross-Linking Adhesives Uniting Water Resistance, Low-Temperature Stability, Recyclability, Degradability, and Fluorescence.

In the pursuit of green and sustainable development, there is an urgent demand for environmentally friendly adhesives that maintain a stable adhesion under harsh conditions. In this work, bioinspired by the synergistic mechanisms of mussel proteins, we designed a readily accessible and environmentally friendly catechol-functionalized cross-linking adhesive (MPCs) via molecular engineering and thiol-ene click chemistry. By optimizing solvent selection, we preserved a higher density of phenolic hydroxyl groups, significantly enhancing the interfacial adhesion. The resulting adhesive reaches remarkable lap shear strengths of 2.13 MPa in 63 °C water and 1.75 MPa in liquid nitrogen (-196 °C), surpassing most reported catechol-based adhesives. Notably, MPCs exhibit excellent recyclability through thermal reprocessing, retaining strong adhesion even after 10 reuse cycles. Mechanical testing reveals a tensile strength of up to 48 MPa, while the inherent π-π interactions between benzene rings confer photoluminescence under UV irradiation. This property enables fluorescence-based damage detection, as localized mechanical damage causes measurable intensity shifts. Furthermore, MPCs could degrade controllably through ester-linkage hydrolysis in the cross-linker, generating products with excellent biocompatibility. This work not only advances the design of bioinspired adhesives but also provides a sustainable solution for marine-environment and extreme-environment applications.