Fluorine-containing polyimide nanofiber membranes for durable and anti-aging daytime radiative cooling

Personal daytime radiative cooling (PDRC) materials have high sunlight reflection and high selective emissivity to outer space in the main atmospheric window, demonstrating huge potential in energy-saving for sustainable development. Recently, polymer-based membranes for radiative cooling have been widely reported, due to their easy processing, low cost, and unique optical performance. However, the desired high sunlight reflectance of PDRC materials is easily dampened by environmental aging, high temperature, and ultraviolet (UV) irradiation, resulting in reduced cooling performance for most polymers, adverse to large-scale practical applications. In this work, we demonstrate a novel polyimide nanofiber (PINF) membrane with a fluorine-containing structure via typical electrospinning technology. The resultant PINF membrane exhibits high sunlight reflectance, UV resistance, and excellent thermal stability, rendering anti-aging daytime radiative cooling. The sunlight reflectance of PINF membranes could maintain constant in the aging test for continuous 720 h under outdoor solar irradiation, exhibiting durable and long-term personal daytime radiative cooling performance.