A waterproof and breathable cellulosic composite with thermal management inspired by penguins

Temperature is paramount for human body, contributing to a growing demand for enhanced thermal comfort in wearable textiles. However, it is still a major challenge to prepare multifunctional thermal comfort materials with integrated insulation strategies. The Antarctic penguin uses its feathers to maintain body temperature by three different functional layers, namely photothermal conversion layer, thermal insulation layer and infrared reflective layer. Inspired by this biological model, a thermal comfort cellulosic composite has been developed featuring analogous functional layers similar to penguin feathers to adapt the thermal properties that penguin feathers serve. The outermost layer comprises a polyacrylonitrile (PAN) @carbon nanotube (CNT) -polydimethylsiloxane (PDMS) layer fabricated via electrospinning and spraying, where CNTs impart photothermal conversion capability with 60 % absorbance and PDMS confers water resistance. Then, the middle layer consists of porous cellulose, exhibiting low thermal conductivity (0.0456 W/m·k). The innermost layer features Ag nanoparticles, with 90 % infrared reflectivity to reduce heat loss. Simultaneously, the cellulosic composite exhibits effective active thermal management, allowing rapid heating with low voltage. Furthermore, this composite has superior breathability comparable to cotton. Combining passive and active insulation, the multifunctional textile offers thermal insulation, waterproofing, and breathability, making it suitable for various wearable conditions.