A novel synergistic covalence and complexation bridging strategy based on multi-functional biomass-derived aldehydes and Al(III) for engineering high-quality eco-leather.

To get rid of the chrome pollution faced by the leather industry, we explored a novel engineering high-quality eco-leather technology based on the synergistic interactions between biomass-based aldehydes and Al(III). Firstly, dialdehyde xanthan gum (DXG) was prepared to covalently crosslink with the collagen fibers (CFs) via Schiff-base linkages under alkaline conditions, endowing the leather with a shrinkage temperature (Ts) of 80 °C and opening channels for the subsequent penetration of Al species (AL). Secondly, and for this latter purpose, the DXG-tanned leather was acidified to release part of the DXG from the leather according to the dynamic nature of the Schiff-base. Containing suitable oxygen-containing groups (OGs) with excellent complexation capabilities, the released DXG served as masking agents for AL, facilitating the penetration of AL into the inner CFs network for further complexation crosslinking. Consequently, a denser crosslinking network was constructed in the leather, and the crust leather exhibited higher Ts (82.2 °C), improved mechanical (tensile strength: 13.4 N/mm2, tear strength: 53.3 N/mm) and organoleptic properties than those of the DXG crust or AL crust leathers. This demonstrates that this synergistic covalence and complexation bridging strategy is a sustainable option to substitute highly restricted chrome tanning agent for eco-leather production.