Pages 141–145
Abstract
Research summary supplied by the authors
To mitigate chromium pollution in leather manufacturing, we developed a novel biomass-based chrome-free tanning agent (polyphenol–cyanuric chloride derivative, PCC) by grafting cyanuric chloride (CC) onto tea polyphenol (TP). Exploiting the pH-responsive phenolic hydroxyl groups of TP, PCC exhibits a phase-adaptive tanning mechanism: it permeates collagen as nanoscale particles (100–200 nm) under mildly acidic conditions (pH 4.5–6.0), then undergoes HCl-triggered supramolecular selfassembly into micron-scale networks (<“2000 nm) via ð–ð stacking under strong acidity (pH < 3.0). This biphasic behavior enables salt-free processing while promoting complete collagen cross-linking, evidenced Fig. 1 Graphic for paper by an increased shrinkage temperature (Ts) of 80.7 ± 1.2 °C, comparable to commercially available glutaraldehyde tanning agents. PCC-tanned leather shows improved fullness and photostability; yellowing is suppressed after UV aging ( 4.0). Supporting measurements indicate markedly reduced effluent burdens (COD 850 mg/L; TDS 420 mg/L) versus conventional chrome and aldehyde systems. Overall, this work demonstrates a practical route to convert agricultural polyphenols into high-performance, ecofriendly tanning materials through pH-driven in situ self-assembly. Δb* Δb*