Natural dyes and regenerated cellulose fibers blending using ionic liquid as a common platform for sustainable textiles/fashion applications

Abstract

Conventional textile dyeing generates significant water pollution through synthetic dye leaching, creating urgent need for closed-loop processes. The current work uses a novel in-situ spin dyeing process to develop dyed cellulose fibers, using ionic liquid (IL) as a unified platform to dissolve cellulose and disperse a range of natural dyes – eliminating post-spinning coloration. The spin dyeing method effectively requires less water uptake and is a sustainable benign method for the future textile industry. Different natural dyes were incorporated into the cellulose-IL composite solution to add vibrant colors to the fibers. Natural dyes derived from Sorghum, and Coreopsis show better conjugation with the wet-spun fibers, while the other dyes do not show similar levels of dye stability and incorporation within the fibers. FTIR results confirmed chemical bonding of dyes in the fibers. SEM images indicated the homogeneous dispersion of dye across the fibers. The resultant dyed fibers demonstrate similar mechanical properties in comparison to the neat cellulosic fibers, and commercially available fibers. Although thermal stability decreased for the dyed fibers, mechanical performance validates IL-mediated spin-dyeing as a viable alternative to petroleum-based dyes. This first demonstration of ILs enabling integrated fiber production and natural dyeing establishes a blueprint for sustainable textiles manufacturing.