Robust and Sustainable Starch Adhesive Inspired by the Feline Meniscus

Abstract With the continual reinforcement of low-carbon and environmental protection concepts, the development of high-performance formaldehyde-free bio-based adhesives has become a research hotspot in application fields. The robust meniscal structure is composed of a rigid, interwoven fiber skeleton and a glycosaminoglycan-rich buffering layer. In this study, citric acid was used as a cross-linking agent to react with active groups on starch, thereby constructing a rigid cross-linking network. Meanwhile, hyperbranched polyurea (HPU) was introduced into the adhesive system via covalent and hydrogen bonding, serving as a buffer layer to dissipate stress and enhance system toughness. Compared with the unmodified starch adhesive, the pre-pressing strength of SA/HPU10 adhesive was increased to 0.80 MPa, representing an increase of 700%. Dry and wet shear strengths were increased to 1.94 MPa and 1.31 MPa, respectively, corresponding to increases of 84.8% and 627.8%, respectively. The work of adhesion was increased by 830.6% to 1270.3 mJ, and toughness was significantly enhanced. In addition, the coating performance and mold resistance were significantly improved through biomimetic modification. Together with the life cycle assessment results, these findings indicate that the bio-based biomimetic SA/HPU10 adhesive has considerable potential to balance environmental sustainability and practical performance and may serve as a next-generation adhesive.