Flexible Radiative Cooling Textiles Based on Bark‐Like <scp>SA</scp> ‐ <scp> Al ₂ O ₃ </scp> @ <scp> TiO ₂ </scp> Fibers for Personal Thermal Management

ABSTRACT Radiative cooling textiles have garnered significant attention due to their ability to maintain sub‐ambient temperature without energy input. Herein, novel flexible fibers with a bark‐like surface structure were developed by using a dry‐wet spinning technique. The resultant SA‐Al 2 O 3 @TiO 2 fibers exhibited excellent mechanical properties, with tensile stress and strain of 42.2 ± 2.4 MPa and 280% ± 20%, respectively. Meanwhile, SA‐Al 2 O 3 @TiO 2 fibers possess ultra‐high solar reflectance of 99.5% and infrared emissivity of 99.8% in the atmospheric window. Moreover, it is interesting to find that the bark‐like surface structure of SA‐Al 2 O 3 @TiO 2 fibers contributes to accelerating heat dissipation when air circulation is present. Compared with the common white cotton textiles, the textiles based on bark‐like SA‐Al 2 O 3 @TiO 2 fibers obtained a temperature drop of 6.3°C under the air circulation environment. Outdoor tests demonstrated the maximum cooling temperature of SA‐Al 2 O 3 @TiO 2 fiber‐based textiles under direct sunlight can reach 12°C when compared with the white cotton textile. Furthermore, the SA‐Al 2 O 3 @TiO 2 fiber‐based textiles can maintain 99% of their cooling efficiency after UV exposure for 72 h. Therefore, this work provides a viable strategy for designing radiative cooling fibers, which display great potential for personal thermal management.