<scp>PTFE</scp> / <scp> CaF ₂ </scp> / <scp> TiO ₂ </scp> Synergistic Low‐Cost Radiative Cooling Porous Membrane: Wet Non‐Solvent Phase Separation Green Forming and Performance Control

ABSTRACT In response to the bottlenecks of high cost, solvent pollution, and poor environmental adaptability of Passive Daytime Radiative Cooling (PDRC) materials, this study innovatively developed a PTFE/CaF 2 /TiO 2 ‐PVDF composite porous membrane via wet non‐solvent induced phase separation (NIPS) technology. Low‐temperature plasma modification was employed to enhance the dispersibility of PTFE. Combined with a DMF‐based solvent system and a three‐stage gradient recycling process, green preparation was achieved (solvent recovery rate of 91.8%, volatile organic compounds (VOCs) emissions reduced to 1.04 kg t −1 ); the synergistic substitution with PTFE/CaF 2 reduced raw material costs by approximately 28%, while maintaining high infrared emissivity. The resulting film (500 μm) exhibits excellent optical properties (reflectance of 99.7% in the 0.4–2.5 μm visible‐NIR band, peak emissivity of 0.967 in the 7–14 μm atmospheric window) and notable cooling performance (peak sub‐ambient temperature drop of 8.0°C under 1350 W m −2 solar irradiance, a 75% improvement over pure PVDF). Gradient TiO 2 (20 nm–1 μm) imparts UV shielding and anti‐fouling functionality; the micro‐nano porous structure (contact angle 98°) synergistically delays UV aging. This research provides a low‐cost and scalable radiative‐cooling material platform with potential applications in building energy efficiency, electronic thermal management, and photovoltaic thermal management.