Improving passive daytime radiative cooling via incorporation of composite nanoparticles into sheath of PU-PVDF core-sheath nanofiber film

Abstract

Climate change has recently caused more severe temperatures, increasing demand for personal thermal management outdoors. Radiative cooling fabrics, known for their potent cooling ability, play a crucial role in regulating the thermal balance of the human body in high-temperature environments. In this study, an innovative PU (polyurethane)-SiO2/TiO2@PVDF (polyvinylidene fluoride) core-sheath nanofiber film was developed by incorporating SiO2/TiO2 composite nanoparticles (STNs) into the sheath of the nanofibers through coaxial electrospinning. The PU-STNs@PVDF composite nanofiber film with thickness of ∼100 μm achieved a reflectance of 92 % in the visible to near-infrared spectral range and an emittance of 91 % within the atmospheric transparent window. The temperature of the PU-STNs@PVDF core-sheath nanofiber film was reduced by 6.9 °C and 4.7 °C compared with that of the cotton fabric and PU-PVDF nanofiber film, respectively. Under direct solar radiation in summer, the temperature of the PU-STNs@PVDF core-sheath nanofiber film was 7.7 °C lower than that of cotton fabric. The PU-STNs@PVDF core-sheath nanofiber film elongated at a break of 127.5 % and a tensile strength of 4.3 MPa, implying it promising flexibility. The PU-STNs@PVDF core-sheath nanofiber film possesses huge potential in personal thermal management.