A meniscus-inspired, environmentally robust, tough soybean-based adhesive

The development of sustainable and versatile formaldehyde-free bio-based adhesives is currently a research focus in materials science. However, their practical extensive applications are often limited by their high brittleness and poor performance. Inspired by the robust structure of the meniscus (composed of a rigid framework of interwoven collagen fibers and a flexible buffer layer of the glycosaminoglycan matrix), this study utilizes poly(ethylene glycol itaconate) (EIA) synthesized from itaconic acid derived from the fermentation of crop straws as a buffer layer. Through hydrogen bonding, EIA is introduced into the rigid cross-linked network of soy protein, resulting in the development of a robust adhesive (SM/EIA). The adhesion work of the optimized SM/EIA adhesive was increased by 458% (0.424 J), demonstrating superior toughness. The dry/wet shear strength reached 2.05 MPa and 1.13 MPa, representing increases of 37.6% and 289.7%, respectively, exhibiting exceptional bonding capabilities for wood substrates. The as-designed adhesive also shows versatile bonding performance for diverse substrates, including ceramics and metals. Additionally, it exhibited excellent water retention, coating applicability, and pre-press performance, along with notable mold resistance and flame-retardant properties. Combined with life cycle assessment, the biomimetic design offers novel perspectives for advancing adhesive systems, facilitating the replacement of conventional petroleum-based adhesives through systematic integration of renewable resources and structural bioinspiration.