Chitosan-Based Polymeric Dyes for In Situ Coloration of Regenerated Cellulose Fibers

Abstract

Conventional aqueous textile dyeing consumes large quantities of inorganic salts, generating high-salinity wastewater and considerable environmental burdens. Herein, an in situ coloration strategy was developed by covalently coupling chromophores to chitosan and incorporating the resulting polymeric dyes into cellulose fibers during wet spinning, in which chitosan-based polymeric dyes were prepared through covalent coupling of chromophores with chitosan in a low-temperature homogeneous system and subsequently incorporated into regenerated cellulose fibers during wet spinning. Structure analyses confirmed the successful incorporation of the polymeric dyes into the regenerated cellulose fibers. The polymeric dye solution containing 2 wt % chitosan exhibited satisfactory stability. When blended with a 5 wt % cellulose solution and wet-spun using phytic acid solution as the coagulation bath, the dye retention in the regenerated filaments reached 89.7%. The filaments containing 1 wt % chitosan and a Reactive Red 195 loading of 200% exhibited a tensile strength of 110 MPa. The regenerated cellulose fibers exhibited balanced mechanical properties, with a favorable combination of strength, stiffness, and extensibility. Moreover, the incorporation of chitosan imparted antibacterial activity to the fibers, with bacterial reduction rates of 88.02% against Escherichia coli and 75.38% against Staphylococcus aureus. By integrating dye synthesis, fiber formation, coloration, and functionalization into a single process, this approach provides a viable pathway to reduce salt consumption and wastewater generation.