Nanosphere-structured hierarchically porous PVDF-HFP fabric for passive daytime radiative cooling via one-step water vapor-induced phase separation

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-03, Vol.460, p.141581, Article 141581
• Main Authors: Cheng, Ningbo, Miao, Dongyang, Wang, Chao, Lin, Yanyan, Babar, Aijaz Ahmed, Wang, Xianfeng, Wang, Zhaohui, Yu, Jianyong, Ding, Bin
• Format: Article
• Language: English
• Subjects: Electrospinning; Hierarchically porous fiber; Interconnected nanosphere structures; One-step; Passive daytime radiative cooling; Water vapor-induced phase separation
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.141581

[Display omitted] •Nanosphere-structured PVDF-HFP fibers with hierarchically porous structures are fabricated.•A facile strategy for unique structures via one-step electrospinning based on water vapor-induced phase separation using single solvent was developed.•The as-prepared fabric offers excellent spectral selectivity with solar reflectance of ∼93.7 % and infrared emittance of 91.9 %.•Practical radiative cooling characterization showed a temperature drop of ∼13.8 °C compared with cotton.•The obtained fabric presents a high specific surface area (14.43 m2/g) and hydrophobicity (∼135°). Growing demand for efficient and economical cooling for indoor as well as outdoor applications, especially personal cooling in outdoor environments, is a major global challenge today. Currently, tailored optical structures with spectral selectivity are being used as cooling strategies. However, developing these photonic structures generally requires sophisticated multi-step manufacturing processes and use of multiple solvents which limits their acceptability for large-scale production and cost-effectiveness. Therefore, for the first time, herein we report the fabrication of nanosphere-structured hierarchically porous poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) fibrous fabric via a facile one-step electrospinning process based on water vapor-induced phase separation (WVIPS) technique using single solvent. The fabricated fabric with interconnected nanospheres structure and hierarchically porous fibers possessed large roughness and high specific surface area. Cooling performance of the fabricated PVDF-HFP fabrics was evaluated using skin simulators to mimic human body. The as-prepared PVDF-HFP fabric exhibits a superior average solar reflectance (∼93.7 %) and infrared emittance (∼91.9 %), yielding a temperature drop of ∼19.8 °C and ∼13.2 °C compared to the bare skin simulator and the one covered with cotton fabric, respectively, under solar intensity of ∼950 W m−2. Additionally, excellent hydrophobicity and adsorption make designed fabrics potentially suitable materials for not only radiative cooling but also for waterproof and filtration applications.