Anchoring adhesives on multi-network hydrogels derived from chrome leather scraps with high strength and underwater...

Hydrogels have been promising for high-humidity applications, including underwater restoration and underwater medicine. However, conventional hydrogels exhibited poor mechanical properties and loss of adhesion due to the hydration layer in a humid environment. Herein, an underwater adhesive hydrogel based on waste chrome leather scraps with high strength was devised through multi-network structure design and surface-anchored adhesive. Firstly, a multi-network hydrogel was constructed by using waste chrome leather scraps hydrolysate as the first network, polyacrylamide as the second network, and polysulfonate as the third network. Subsequently, the adhesive poly(dopamine methacrylamide-co-methoxyethyl acrylate) was anchored onto the surface of the multi-network hydrogel, which effectively enhanced the adhesion property of the hydrogel. The hydrogel demonstrated remarkable adhesion in aqueous environments (adhesive strength greater than 200 kPa), which was attributed to the adhesion and hydrophobic groups in the adhesive. Furthermore, the synergistic effect of the three networks resulted in an excellent compressive strength of the hydrogel (40 MPa compressive strength, 95% compression deformation). The findings of this work open a promising direction on how to convert waste chrome leather scraps into high value-added products and develop effective high-performance underwater adhesives, which offer a promising material for applications requiring mechanical strength and underwater adhesion.