A Circular Manufacturing Platform for High-Performance Cellulosic Fibers via Hydrogen-Bond Unzipping and Rezipping.

This study outlines a closed-loop manufacturing process for cellulosic fibers designed to meet the textile industry's urgent demand for eco-friendly, cost-effective solvents, circular-design principles, and superior material performance. The process utilizes a deep eutectic solvent composed of calcium chloride, formic acid, and water, which effectively facilitates cellulose dissolution and partial esterification. Followed by dry-jet wet spinning and ethanol-induced coagulation, the initially disordered cellulose chains are reorganized into an ordered, compact fibrillar structure. The resulting fibers showcase a relative crystallinity of 63.9%, tensile strength of 222 MPa, elongation exceeding 20%, and thermal stability above 180°C. Furthermore, they possess textile-relevant properties including thermal conductivity of 0.064 W·m-1·K-1, moisture regain of 12.4%, and luster comparable to cuprammonium rayon. Significantly, the process allows for the concurrent recovery of both the solvent and coagulant, maintains fiber reusability, and minimizes waste and costs. The life-cycle assessment indicates that this approach significantly reduces the carbon footprint and resource depletion compared to conventional rayon production. These findings establish a cost-effective, eco-friendly alternative to current solvent systems, addressing both environmental and industrial needs.