Tailoring body surface infrared radiation behavior through colored nanofibers for efficient passive radiative heating textiles

Passive radiative heating textile offers an energy-saving pathway to increase body temperature in cold weather. However, the basic properties of clothing, such as color and comfort, are usually overlooked in the design of radiative heating materials, because conventional fiber materials cannot meet the needs of infrared thermal management. Herein, we achieved low infrared emissivity of the textile by reducing the fiber diameter to the submicron level through electrospinning. The electrospun polymer molecules can achieve uniform mixing with dye molecules during the preparation of the spinning solution. And the color depth of the prepared polyacrylonitrile nanofiber (NanoPAN) fabric can be turned by a scalable solvent impregnation method. Through compounding the Ag coating layer, the colored NanoPAN/Ag textile shows high solar energy utilization of 50% and low mid-infrared (IR) emittance of 15%, realizing superior IR heating performance. The resulted NanoPAN/ Ag textile maintains human body temperature at 33-35 degrees C at a cold ambient temperature of 14 degrees C, while, in the case of using dyed cotton fabrics, the body temperature will drop below 33 degrees C. Moreover, due to the use of nanofiber, the colored NanoPAN/Ag textile has outstanding water vapor transmission rate, water evaporation rate, breathability and mechanical stability, exhibiting great potential for practical application in infrared thermal management textile.