Sustainable Biomass-Caffeic Acid Hybrid Adhesives via Dynamic Covalent and Metal–Ligand Coordination Networks

Abstract

Adhesives are crucial for bonding diverse substrates in electronics, aerospace, and precision manufacturing, but traditional ones suffer from insufficient durability, poor low-temperature performance, and limited environmental adaptability. This study develops a high-performance supramolecular adhesive (poly(Cu-BTC-CA)) via a stepwise polymerization strategy: Cu-BTC (MOF) is synthesized first, then functionalized with caffeic acid (CA) to form a dual cross-linked porous network. FT-IR confirms coordination/polymerization interactions. Poly(Cu-BTC-CA) shows robust adhesion to diverse substrates, including stainless steel, copper, aluminum, and glass. More remarkably, this MOF-based adhesive exhibits a distinctive low-temperature reinforcement effect, with its adhesion strength on stainless steel increasing to 6.2 MPa at −80°C—a counterintuitive enhancement rather than the usual decline. It also retains effective bonding after exposure to liquid nitrogen (−196°C), with partial recovery upon warming to room temperature. In addition, the adhesive demonstrates outstanding macroscopic load-bearing performance: a mere 62.5 mg of material over a 625 mm² overlap area can stably support a 30 kg load without interfacial debonding. This work provides a novel design for adhesives with excellent strength, wide temperature adaptability, and great potential for extreme-environment applications.