Mussel-Inspired Green In Situ Lignin Regeneration Strategy for Plant Fiber Surface Reconstruction toward Strong Yet Tough Soybean Meal Adhesive with Mildew Resistance

High Resolution Image Download MS PowerPoint Slide The manufacturing of wood-based panels necessitates biomass adhesives characterized by high mechanical strength and superior toughness. As promising alternatives to nonrenewable, toxic formaldehyde-based adhesives, soybean meal (SM) adhesives have garnered significant attention. Nevertheless, owing to the inherent stiffness-toughness trade-off, plywood commonly undergoes brittle fracture and is susceptible to damage and deformation flaws throughout its manufacturing and service life. Herein, inspired by the adhesive mechanism of mussel proteins, dopamine-mimetic functionalized rough kenaf fibers (ADKF) were fabricated via an eco-friendly and sustainable approach using a ternary deep eutectic solvent (DES) system. This strategy was designed to simultaneously dissolve and functionalize the intrinsic lignin within kenaf fibers (KF), subsequently anchoring it onto the KF surface, which, in turn, enhanced the interfacial compatibility between the KF and SM adhesive. Ultimately, by constructing a multicross-linking network, a high-strength SM-based adhesive with excellent toughness was developed through the synergistic addition of ADKF, copper ions, and triglyceride amine. The wet shear strength of the resultant SMG/ADKF@Cu adhesive reached 1.05 MPa, which was 400% higher than that of the pure SM adhesive. The synergistic effects of the bridging role of ADKF and the formed sacrificial bond structures contributed to the enhanced toughness of the adhesive, with the debonding work reaching 0.297 J. Furthermore, the SMG/ADKF@Cu adhesive exhibited better moisture resistance and mildew resistance (5 days). This sustainable and eco-conscious design for biomimetic functionalized KF utilization provides an effective pathway for valorizing lignocellulosic waste, offering novel paradigms for developing high-performance protein-based adhesives.