Low-Temperature Dyeing of Polylactic Acid Fabrics with Microbial Prodigiosin Enabled by Natural Deep Eutectic Solvent Treatment

Polylactic acid (PLA), a biodegradable polymer derived from renewable resources, represents a promising candidate for sustainable textiles. Nevertheless, its practical application remains limited by the requirement for high-temperature dyeing, which can induce polymer hydrolysis and lead to the loss of fiber strength. To address this limitation, PLA fabric was treated with an eco-friendly natural deep eutectic solvent (NaDES) composed of glycerol and citric acid. The treatment was found to enhance fiber surface roughness and internal looseness, which facilitated dye diffusion and allowed for a significant reduction in dyeing temperature. When dyed with microbial prodigiosin, the treated PLA fabric achieved a color depth at 70 °C that was equivalent to untreated fabric at 90 °C, while also exhibiting a 93.56% bacteriostatic rate against Staphylococcus aureus due to the inherent antibacterial property of microbial prodigiosin. This work provides a novel and sustainable strategy for the eco-friendly dyeing of PLA textiles.