Anisotropic Polytetrafluoroethylene-Based Aerogels with Hierarchical Architecture Enabled Versatile Passive Radiative Cooling

Conventional polymer-based radiative cooling materials often exhibit limited functional integration and poor stability under complex environmental conditions, restricting their application in multifunctional practical scenarios. Here, a multifunctional anisotropic polytetrafluoroethylene (PTFE) based aerogel was fabricated by constructing a directional porous architecture via unidirectional freezing, combined with the incorporation of fluorosilane-modified silica (SiO2) nanoparticles. The tailored structure effectively suppressed shrinkage and deformation during sintering, enhanced porosity and surface hydrophobicity, and imparted excellent oleophilic absorption capacity. Benefiting from the high infrared emissivity of the Si–O–Si network in the atmospheric window (elevated to 94.5%) and the structure-induced solar reflectance (increased to 94%), the aerogel achieved all-day passive radiative cooling with temperature reductions of ∼10.1 °C during the daytime and ∼4.3 °C at night under outdoor conditions. The structural design strategy proposed in this work provides insights into developing highly stable and multifunctional radiative cooling materials, and also opens possibilities for multifunctional energy conservation applications of PTFE-based aerogels.