Development and evaluation of porous poly-L-lactic acid (PLLA) fibrous membrane for effective radiative cooling applications

One-step electrospinning via NIPS produced highly porous PLLA membranes. • Achieved high solar reflectance (∼95.7%) and strong mid-IR emission. • Porous morphology enabled 2.6–3.9 °C cooling vs smooth PLLA. • Up to 9.2 °C reduction compared with cotton under sunlight. • Scalable, low-cost route for flexible daytime radiative cooling textiles. The growing demand for efficient and cost-effective cooling solutions, both indoors and outdoors, especially for personal cooling in outdoor environments, posses a significant global challenge. Current cooling methods often rely on custom optical structures with spectral selectivity, which typically involve complex manufacturing processes, limiting their large scale production and cost-effectiveness. This study aims to develop a radiation cooling material by utilizing the porous structure of poly- L -lactic acid (PLLA) through one-step electrospinning method based on the Non-solvent induced phase separation (NIPS) technique. The resulting membrane, with porous structure, exhibits substantial roughness and a high specific surface area, revealing an impressive average solar reflectance (∼95.7%) under wavelength of (0.25 ∼ 2.5 μm) and mid infrared emittance (∼88.3%) under wavelength of (8 ∼ 13 μm). The study evaluates the indoor cooling performance of porous PLLA, resulting in temperature reductions of approximately 2.6∼3.9°C and 5∼9.2°C compared to smooth PLLA and cotton-covered surface, respectively, under different solar intensities. It also explores the potential of porous PLLA for outdoor cooling applications, emphasizing its hydrophobic, mechanical, and flexible properties. It proposes a cost-effective method for producing high-performance radiative cooling materials using PLLA and underscores its versatility for practical applications.