Facile and eco-friendly dyeing process based on UV-induced photografting to immobilize halochromic dye on nylon 6 fabric for acidic gas detection

The employment of colorimetric textile sensors based on halochromic dyes enable the visual detection of gas leaks, without the need for additional instruments, and are thus advantageous for the immediate detection of hydrochloric acid. Despite their potential utility, the widespread use of halochromic dyes is impeded by their poor dyeability and washfastness on nylon fibers. Herein, we introduce an environmentally sustainable UV-induced photografting method to dye nylon 6 fabrics and enhance the dyeability and wash fastness of hal-ochromic dyes. This method employs UV radiation to generate radicals that facilitate the covalent bonding of the radical-sensitive groups on the dye and fiber, which significantly reduces dye leaching. Colorimetric nylon sensors fabricated using a graftable rhodamine dye with exceptional pH sensitivity via a UV-induced photo-grafting method. The sustainability of the UV-induced photografting method and the gas detection performance, durability, and reusability of the fabricated textile sensors are investigated. The fabricated sensors demonstrate rapid detection rates of <10 s, exhibit distinctive color changes (Delta E >20) upon exposure to hydrogen chloride at concentrations as low as 1 ppm, and show excellent durability (washfastness level: 4-5, performance retention rate after washing: 97 %) and reusability after ten washing/drying cycles. Furthermore, the UV-induced pho-tografting method is more environmentally sustainable than conventional dyeing methods owing to its low solvent consumption (-97 %), low energy consumption (-84 %), and relatively short process time (-45 %).