Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE A sustainable DMF–NIPS process produces a hierarchically porous PTFE/CaF2/TiO2–PVDF membrane for passive daytime radiative cooling. The membrane combines high solar reflectance with strong thermal emissivity, achieving approximately 8.0°C sub-ambient cooling together with 91.8% solvent recovery and 28% raw-material cost reduction for scalable energy-saving applications.

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/CaF2/TiO2-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/CaF2 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 TiO2 (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.