Multifunctional amphoteric heteropolymer for chromium free sustainable leather process

Abstract The post‐tanning process of leather making involves the of large quantities of auxiliary chemicals to enhance the functionalities of the leather. Hence, developing multifunctional polymers are essential to reduce the pollution load and enhance sustainability. Herein, we report the synthesis of multifunctional retanning and fatliquoring agent using a hydroxyethyl methacrylate (HEMA) monomer by modifying the hydroxyl group to carboxyl and long‐chain hydrocarbon along with quaternary ammonium monomer. The resulting polymer has been subsequently used in the tanning and post‐tanning process. The influence of the carboxyl group increases the metal uptake of the aluminum (twofold) and zirconium (1.5‐fold) tanning agent, and hydrothermal stability of the polymer‐treated leathers is 74 and 81°C for aluminum and zirconium tanning, respectively. The experimental leather showed uniform pore size distribution and better organoleptic characteristics than the control. Introducing the quaternary ammonium group in the polymer increased dye exhaustion in the experimental process up to 97%. The anti‐bacterial studies show the polymer is effective against gram‐positive species due to electrostatic interaction. The biochemical analysis of the experiment process shows higher biodegradability (0.62). Thus, the present study opens a new avenue for a sustainable replacement for conventional post‐tanning chemicals.