Engineering an epoxy tanning agent via facile functionalization of sucrose with silane coupling agent for sustainable leather production

Developing chrome-free tanning agents to manufacture eco-leather products is the most promising way to address chrome pollution and achieve a sustainable leather industry. Herein, we report on a facile strategy to synthesize a novel biomass-based epoxy tanning agent (BET) based on sucrose and γ-(2,3-epoxypropoxy) propytrimethoxysilane (KH560). FTIR, XPS, ²⁹Si NMR, and GPC analyses confirmed the reaction between sucrose and KH560 via forming Si–O–C bonds, suggesting the successful preparation of BET. The subsequent application experiments showed that the BET-tanned leather demonstrated superior performance with a well-organized collagen fiber network and a shrinkage temperature exceeding 80 °C, outperforming commercial TWS-tanned leather in thermal stability during post-tanning and resistance to yellowing. Moreover, the BET-tanned crust leather exhibited enhanced tensile strength (25.65 vs. 16.18 N/mm²) and tear resistance (84.01 vs. 60.71 N/mm) compared to TWS-tanned crust leather, along with reduced extensibility under a specific load and at break. Compared with the TWS-tanned crust leather, the BET-tanned crust leather also displayed superior smooth grain surface, dyeing uniformity, softness, and fullness. These promising results pave the way for developing alternative chrome-free tanning agents, aiding the sustainable development of the leather industry.

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