A Mussel-Inspired Bio-Based Dipping System with Superior Interfacial Anti-Fatigue Adhesion

Enhancing interfacial reliability of fiber-reinforced rubber composites is essential for ensuring overall safety, which was traditionally achieved through resorcinol-formaldehyde-latex (RFL) dipping on fiber frameworks. Nevertheless, the widely used RFL system has come under strict regulation due to its toxicity. Most existing alternatives focus on petroleum-based resins, which lack long-term sustainability. To address this issue, a novel bio-based dipping system was developed as a sustainable and effective substitute for the RFL system. A dopamine-like structure was incorporated to facilitate the formation of the bio-based phenolic resin, and the resin formulation was optimized to yield a robust network and a stable dipping layer. Covulcanization at the fiber-rubber interface ensured robust interfacial bonding. The bio-based dipping system combines the rigidity of phenolic resins with the flexibility of the dopamine-like segments, constructing an interfacial layer with strength comparable to RFL, enhanced toughness, and lower interfacial heat buildup. These contribute to achieving static adhesion comparable to RFL while demonstrating interfacial fatigue resistance up to 49% higher, far exceeding the interfacial fatigue life reported for other fiber-rubber composite systems. Compared to other eco-friendly dipping systems, this work not only upgrades bio-based raw materials but also offers the advantages of a simple one-step process and superior interfacial fatigue resistance, making it a promising solution for both environmental sustainability and high-performance industrial applications.