关键词: 辐射制冷, 个人热管理, 皮芯纳米纤维膜, 纳米颗粒, 同轴静电纺丝

Abstract: This study proposes a design scheme of SiO2/TiO2/PVDF-CA sheath-core nanofiber membranes intended for the emerging passive daytime radiative cooling (PDRC). PDRC is a novel cooling technology that effectively dissipates the heat from objects by achieving a balance in radiative heat exchange, thereby lowering the temperature. Based on high solar reflectance and high and mid-infrared emissivity, this study designed a STNs/PVDF-CA sheath-core nanofiber membrane with a complex microstructure to achieve outstanding radiative cooling performance.
The study began by preparing SiO2/TiO2 nanoparticles (STNs), which exhibited high solar reflectance (90%) and mid-infrared emissivity (95%) within specific ranges. It is confirmed by using TEM and XRD techniques to analyze the morphology and structure of STNs that TiO2 synthesized by hydrothermal method is coated on the surface of SiO2. Moreover, it is found that STNs have a significantly higher average reflectance in the ultraviolet to near-infrared wavelength range compared to SiO2. Additionally, it confirms a positive correlation between the increase in nanoparticle diameter and the peak shift of reflectance towards longer wavelengths within a certain range. Subsequently, STNs/PVDF-CA nanofiber membranes with CA as the core layer and STNs/PVDF as the sheath layer were prepared by using coaxial electrospinning.
Further experiments demonstrate that embedding STNs into PVDF-CA sheath-core nanofiber membrane achieves excellent solar reflectance capabilities. Furthermore, the nanofiber membrane exhibits significant emissivity within the atmospheric transparency window, providing ideal mid-infrared emission performance for PDRC. The study validates the cooling effect of the STNs/PVDF-CA sheath-core nanofiber membrane through a series of experiments, including simulated sunlight exposure and outdoor testing in high-temperature environments. The results indicate significant superiority in temperature reduction compared to cotton fabric, with a maximum cooling effect of 7.1°C.
In conclusion, the STNs/PVDF-CA sheath-core nanofiber membrane excels in solar reflectance and mid-infrared emission, offering a novel and efficient solution for PDRC technology. This study not only showcases the outstanding performance of the nanofiber membrane in high-temperature environments but also provides an alternative approach to improve personal thermal comfort.

Key words: radiative cooling, personal thermal management, sheath-core nanofiber membrane, nanoparticles, coaxial electrospinning