Daytime radiative cooling is a burgeoning cooling technology that reflects solar irradiation and radiates heat to outer space (3 K) to cool down terrestrial objects without using external energy. However, previously reported radiative cooling materials require complex technology, expensive equipment, or harmful chemicals, most of which are easily contaminated during outdoor applications. In this work, we proposed a simple and eco-friendly method with water as template to fabricate robust superhydrophobic porous polydimethylsiloxane (PDMS) radiative cooling film. The film possesses strong reflectivity and emissivity which results in outstanding cooling performance with ambient temperature drop of 11.52 °C, and has a superhydrophobic property with water contact angle of 165.7° and a sliding angle of 2.1° which results in excellent self-cleaning function. In addition, the prepared film shows low thermal conductivity of 0.1063 W m⁻¹ K⁻¹ which efficiently suppresses the heat exchange because of the air-filled voids within the film. Combining the self-cleaning property to prevent the surface from outdoor contamination or wetting, the film is promising to be widely used for long-term cooling for outdoor applications.

Graphical abstract

A superhydrophobic porous polydimethylsiloxane (S-P-PDMS) daytime radiative cooling film with high reflectivity and emissivity was prepared by a simple and eco-friendly template method, which achieved a cooling effect with sub-ambient temperature drop of 11.52 °C.

中文翻译：

---

用于日间辐射冷却的耐用超疏水多孔膜的环保制备

日间辐射冷却是一种新兴的冷却技术，它可以反射太阳辐射并将热量辐射到外层空间（3K），从而在不使用外部能量的情况下冷却地球物体。然而，先前报道的辐射冷却材料需要复杂的技术、昂贵的设备或有害化学物质，其中大部分在户外应用中很容易受到污染。在这项工作中，我们提出了一种简单且环保的方法，以水为模板制备坚固的超疏水多孔聚二甲基硅氧烷（PDMS）辐射冷却膜。该薄膜具有很强的反射率和发射率，在环境温度下降11.52°C时具有出色的冷却性能，并具有超疏水性，水接触角为165.7°，滑动角为2°。1° 可实现出色的自清洁功能。此外，制备的薄膜显示出0.1063 W m的低热导率^-1  K ^-1由于薄膜内充满空气的空隙，有效地抑制了热交换。结合自清洁特性，防止表面受到室外污染或润湿，该薄膜有望广泛用于室外应用的长期冷却。

图形概要

采用简单环保的模板法制备了一种具有高反射率和发射率的超疏水多孔聚二甲基硅氧烷（SP-PDMS）日间辐射降温膜，实现了亚环境温降11.52 ℃的降温效果。