Ultrabreathable Open-Cell Hierarchical Pore Structure for Radiative Cooling Protective Membranes

Personal protective clothing is essential in biochemical threat environments, however balancing protection, thermal comfort, and breathability remains a significant challenge. This work introduces a novel, skin-friendly ultrabreathable radiative cooling protective membrane (Ub-RCPM), which is developed via a one-step evaporation-induced pore formation process. The sequential evaporation of solvent and nonsolvent during the process endows an ultrabreathable open-cell hierarchical pore structure. By adjusting the open-cell size, Ub-RCPM simultaneously offers high protection, moisture permeability, and passive radiative cooling. The hierarchical pore structure demonstrates a sunlight reflectivity of 94.79% and an infrared emissivity of 94.53% through the infrared atmospheric window, which enables efficient passive cooling. Its open-cell structure enables a water vapor transmission rate of 8904.59 g m^-2 day^-1, 3.5 times higher than that of commercial protection clothing. Additionally, the submicron pores provide a filtration efficiency of 99.1% for 75 nm aerosols. The combination of radiative cooling and ultrahigh breathability enables Ub-RCPM to a temperature lower than commercial protective clothing by 9.6-16.5 °C in real-world conditions. This presents a groundbreaking approach for the design of future thermal comfortable personal protective clothing.