Liu Ling, Shan Xiameng, Hu Xueyan, Lv Weibang, Wang Jin
Nano Science and Technology Institute of University of Science and Technology of China, Hefei 230026, China.
Key Laboratory of Multifunctional Nanomaterials and Smart Systems, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China.
ACS Nano. 2021 Dec 28;15(12):19771-19782. doi: 10.1021/acsnano.1c07184. Epub 2021 Nov 30.
Personal thermal management (PTM) materials have recently received considerable attention to improve human body thermal comfort with potentially reduced energy consumption. Strategies include passive radiative cooling and warming. However, challenges remain for passive thermal regulation of one material or structure in both harsh hot and cold environments. In this work, silica aerogels derived from sodium silicate were prepared through a solvent-boiling strategy, where hydrophobization, solvent exchange, sodium purification, and ambient pressure drying (HSSA) proceeded successively and spontaneously in a one-pot process. This strategy leads to the synthesis of superhydrophobic silica aerogels with extremely low energy consumption without out the use of an ion-exchange resin or low surface tension solvents. Silica aerogels possess a high specific surface area (635 m/g), high contact angle (153°), and low thermal conductivity (0.049 W/m K). A layer-by-layer (LBL) structure including the silica aerogel layer and an extra phase change material layer was designed. The structure demonstrates dual-functional thermal regulation performance in both harsh cold (-30 °C) and hot (70 °C) environments, where the time to reach equilibrium is postponed, and the inner temperature of the LBL structure can be kept above 20 °C in harsh cold environments (-30 °C) and below 31 °C in harsh hot environments (70 °C). A proof-of-concept experimental setup to simulate the illumination of sunlight also proved that the inside temperature of a model car protected by the LBL structure was below 28 °C, while the outside temperature was 70 °C. In addition, these results are well supported by theoretical COMSOL simulation results. The findings of this work not only provide an eco-friendly approach to synthesize silica aerogels but also demonstrate that the LBL structure is a robust dual-functional PTM system for thermal regulation in both harsh hot and cold environments.
个人热管理（PTM）材料最近受到了广泛关注，有望在降低能耗的同时提高人体热舒适度。其策略包括被动辐射冷却和加热。然而，在恶劣的高温和低温环境中，单一材料或结构的被动热调节仍面临挑战。在这项工作中，通过溶剂沸腾策略制备了由硅酸钠衍生的二氧化硅气凝胶，其中疏水化、溶剂交换、钠纯化和常压干燥（HSSA）在一锅法中依次自发进行。该策略可在不使用离子交换树脂或低表面张力溶剂的情况下，以极低的能耗合成超疏水二氧化硅气凝胶。二氧化硅气凝胶具有高比表面积（635 m/g）、高接触角（153°）和低导热率（0.049 W/m K）。设计了一种包括二氧化硅气凝胶层和额外相变材料层的逐层（LBL）结构。该结构在恶劣的寒冷（-30°C）和炎热（70°C）环境中均表现出双功能热调节性能，达到平衡的时间被推迟，LBL结构的内部温度在恶劣寒冷环境（-30°C）中可保持在20°C以上，在恶劣炎热环境（70°C）中可保持在31°C以下。一个模拟阳光照射的概念验证实验装置还证明，由LBL结构保护的模型车内温度在外部温度为70°C时低于28°C。此外，这些结果得到了理论COMSOL模拟结果的有力支持。这项工作的发现不仅提供了一种合成二氧化硅气凝胶的环保方法，还证明了LBL结构是一种强大的双功能PTM系统，可在恶劣的高温和低温环境中进行热调节。
