Not So Dye-Fast

Many of the colorful textile products we use—think clothing, sofas, and carpeting—come courtesy of reactive dye molecules that are designed to adsorb onto and covalently bond to fabric fibers. But during a typical dyeing treatment, up to 40% of the dye molecules hydrolyze and remain only loosely associated with the fibers via electrostatic interactions such as hydrogen bonding. Manufacturers must repeatedly wash and rinse the fabric to get the unsecured dye out, which requires a lot of water, time, and energy. Motivated to make the dye wash-off process more efficient, Richard S. Blackburn of the University of Leeds, in England, introduced vinylpyridine-based polymers into the process to electrostatically attract and shepherd away errant dye (ACS Sustainable Chem. Eng. 2015, DOI: 10.1021/acssuschemeng.5b00034). These polymers, such as poly(vinylpyridine-N-oxide), are already used as additives in laundry detergent to maintain colorfastness. Blackburn and research assistant Nabeel Amin found that using the polymers during dyeing cuts water use in half, reduces processing time by 75%, and consumes 90% less energy.