Bidirectional Phase Separation Spinning Under Natural Drying to Prepare Aerogel Fibers for Thermal Insulation

Abstract Aerogel fibers have emerged as a promising solution in thermal insulation. Yet, the current preparation methods pose challenges: they are either inefficient for continuous production or involve energy‐intensive and time‐consuming steps like freeze‐drying or supercritical drying, thus restricting their practical utility. Here, a bidirectional phase separation spinning technique is introduced for continuous and rapid production (360 m h −1 ) of aerogel fibers at any desired length. Importantly, fibers can be directly dried at room temperature, eliminating the need for energy‐intensive freeze‐drying or other additional steps, significantly reducing energy consumption and processing time. Aerogel fibers produced using this method exhibit remarkable properties: low density (0.18 g cm − 3 ), high porosity (84%), and broad operational temperature range (−20 to 120 °C). Notably, the thermal insulation mat composed of these aerogel fibers achieves an exceptionally low thermal conductivity (31 ± 1.2 mW/(mK)). This work provides a novel strategy for the preparation of aerogel fibers, achieving energy savings and efficiency, positioning aerogel fibers as a promising alternative for next‐generation textiles.