Regenerated Cellulose Aerogel Fibers with Lightweight and Exceptional Mechanical Performance for Thermal Insulation

Abstract Recycling cellulose‐based waste textiles (CBWT) into high‐performance functional materials is a key challenge in sustainable green development strategies. Herein, a combination of water bath wet spinning and gradient solvent exchange methods is employed to develop a regenerated cellulose aerogel fiber (CAF) with excellent mechanical and thermal insulation properties. CAF fibers, with a core‐shell structure, exhibited an excellent mechanical property, with a tensile strength of 16.56 ± 1.48 MPa, a strain at break of 67.9% ± 10.37%, and toughness of 6.65 MJ m −3 in the absence of draft process. Furthermore, the CAF fabrics demonstrated outstanding thermal insulation performance (39.31 mW/m/K), with a temperature difference of 45 °C at 100 °C, significantly reducing heat transfer compared to conventional materials, exhibiting a great promise for use in heat‐resistant and cold‐weather clothing. Most importantly, the process of CBWT dissolution is significantly accelerated by preheating the ionic liquid (IL)/DMSO solution system, which will significantly improve the recycling efficiency and economic benefits of CBWT. This study provides a simple and effective method for fabricating a high‐performance regenerated cellulose aerogel fiber, aiming to promote the development of the textile recycling industry and the innovation of sustainable functional materials.