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 uncontrollable 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 °C, super-ambient heating temperature of ~ 35.8 °C, 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.Graphical Abstract