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

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.