Nanostructured cotton fabrics for personal passive cooling with enhanced thermal conduction and energy saving

Textiles with passive cooling capabilities offer an efficient way to optimize personal thermal regulation. However, the simultaneous achievement of passive cooling, durability, and comfort in a single fabric poses a significant challenge. Herein, an ingenious cotton fabric that can be fabricated through a facile dip-dry technique is proposed. Carboxylated cellulose nanocrystals are grafted onto the fiber surfaces, and then covalently linked with hydroxylated boron nitride nanosheets to form a nanostructured coating. The resulting fabric demonstrates a remarkable enhancement of 69 % in its thermal conductivity and an impressive 56 % rise in in-plane thermal diffusivity, when compared to the pristine cotton fabric. This has the potential to raise the comfort setpoint temperature of indoor cooling equipment by 2.1 degrees C, thereby reducing cooling energy consumption by 22.2 %, while significantly enhancing the perceived cooling effect on the skin. Under the direct sunlight, the nanostructured fabric cools the skin by 1.21 degrees C below ambient temperature, preventing an excessive increase of 8.2 degrees C in skin temperature. Moreover, the resulting fabric maintains comparable levels of comfort and wearability as that of the original cotton fabric. This study presents an innovative strategy towards the development of passive cooling textiles.