An Easy‑to‑Prepare Flexible Dual‑Mode Fiber Membrane for Daytime Outdoor Thermal Management

Excellent outdoor thermal management is vital for public health and safety.However,the ever-changing and uncontrol-lable outdoor environmental conditions,such as irrepressible sunlight and drastic temperature fluctuations,bring majestic challenges to outdoor thermal management.Here,we report a significant advancement toward designing and fabricating a novel fiber membrane with a dual-function of radiative cooling and solar heating for an efficient daytime outdoor thermal management.Unlike the reported dual-mode thermal management materials,which are usually fabricated by compounding organic polymers and metal/inorganic non-metal materials,our fiber-based membrane is composed of only two polymers,i.e.,poly(vinylidene fluoride-co-hexafluoropropene)(PVDF-HFP)and polypyrrole(PPy).The resulting membrane presents outstanding outdoor thermoregulation capacity,with a practically attainable sun-ambient cooling temperature of~4.5℃,super-ambient heating temperature of~35.8℃,in an outdoor environment,under solar intensity(Isolar)of~850 W m^(-2).Fabrication process is simple and cost-effective,which offers the possibility of preparing large-scale products.Owing to the scalable and simple fabrication process,and the exceptional outdoor thermoregulation ability,this dual-mode fiber membrane has great potential to maintain a comfortable outdoor environment for human activities and industrial operations.