Eco-friendly dyeing of polyester, cotton, and wool using novel benzothiazole-based dyes

Traditional dyeing of natural fibers consumes large amounts of water, dyes, auxiliaries, and inorganic salts, leading to serious wastewater discharge and environmental pollution. Supercritical CO 2 dyeing is considered an environmentally friendly and sustainable coloration technology. Its poor dyeing performance on natural fibers remains a critical issue that requires urgent attention. To address this challenge, a benzothiazole-based reactive disperse dye was designed and synthesized from 3-ethylaniline and 2-amino-6-methoxybenzothiazole for the supercritical CO 2 dyeing of cotton and wool. The results showed that the reactive disperse dye achieved effective coloration of cotton and wool, while the precursor exhibited excellent dyeing performance on polyester. Under the optimized dyeing conditions, the K/S values of polyester, cotton, and wool reached 16.45, 5.85, and 5.63, respectively. The washing and rubbing fastness ratings of all dyed samples were above grade 4, except for the staining fastness of cotton on nylon, which was grade 3–4. Thermal and mechanical analyses further indicated that the dyeing process caused limited damage to the fabrics. This study provides a feasible strategy for dyeing both polyester and natural fibers in supercritical CO 2 and offers a sustainable approach for waterless textile coloration.