Abstract

Driven by the increasing demand for high-performance waterproof leather, effective waterproof chemicals have attracted considerable attention. In this work, a series of silicon-containing polyurethane retanning-fatliquoring agents (denoted as Si-WPUC) were successfully synthesized via prepolymerization of isophorone diisocyanate with dihydroxy-terminated polydimethylsiloxane, chain extension with dimethylolpropionic acid, and end-capping with fatty alcohols of varying chain lengths (butanol, octanol, dodecanol, and octadecanol). These Si-WPUC agents were applied in the wet processing of wet-blue goatskin to simultaneously achieve retanning, fatliquoring, and waterproofing functions. The structure of the target products was confirmed by Fourier transform infrared spectroscopy (FTIR). Surface tension and particle size analyses revealed that the Si-WPUC emulsions exhibited good surface activity, nanoscale particle sizes (41.41-53.25 nm), and excellent storage stability. Applied to chrome-tanned goatskin, the crust leather treated with Si-WPUC4 (derived from butanol) exhibited the best performance: a Maeser flex count of 36,406 cycles (exceeding the military-grade standard of 15,000 cycles), a water contact angle of 145.3° on the flesh side, and a solid surface tension reduced to 21.61 mN/m while maintaining satisfactory water vapor permeability. Moreover, the crust leather was imparted with excellent physical properties. This work provides a highly controllable route toward sustainable, high-performance waterproof leather chemicals.