Tough, Waterproofing, and Sustainable Bio-Adhesive Inspired by the Dragonfly Wing

The development of multifunctional bio-adhesive plays a critical role in achieving a sustainable society, where the intrinsic sensitivity to water and poor dynamics severely bottlenecks its scale-up application. Inspired by the microstructure of dragonfly wings, a strong and tough adhesive with excellent reprocessability is designed and developed by creating a dynamic network consisting of a lignin polyurea (LPU) framework with soybean protein (SP). The LPU framework act as the rigid nervures to slow crack propagation and transfer stress, while the SP dissipate the strain energy through the interplay from the graded hydrogen and imine bonds generated between LPU and SP. The bio-adhesive achieves significant enhancements in fracture toughness and water resistance by ≈7 and 23 folds, respectively, compared with SP. Furthermore, the capacity for diffusion and restoration of dynamic network endows the adhesive with superior reprocessability, enabling recycled particleboard to achieve high retention of modules (over 80%). This sustainable bio-adhesive approach offers a promising eco-friendly alternative to the conventional petrochemical adhesive.