Feng Dudong, Witty Andrew S, Birnbaum Fletcher I, Gonzalez Orlando G Rivera, Felicelli Andrea, Lee Won-June, Barber Emily C, Ruan Xiulin
School of Mechanical Engineering and the Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA.
James Tarpo Jr. and Magaret Tarpo Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA.
Adv Mater. 2025 Aug 20:e04382. doi: 10.1002/adma.202504382.
Although significant energy-saving potential of passive daytime radiative cooling has led to diffusively white or reflective surfaces, achieving coloration expands their application for both aesthetic and functional purposes. However, it presents huge technical challenges in scalable processing. This work presents a novel and general self-stratifying approach for creating radiative cooling paints with various colors using selected narrow-band absorption dyes. Applied as a single coat, these paints self-assemble into an absorption-scattering dual-layer structure that efficiently displays color while minimizing light absorption. Three base colors (cyan, magenta, and yellow) are demonstrated to provide full daytime subambient cooling, achieving 93% solar reflectance and 0.94 sky window emissivity. One newly developed black paint achieves 46.3% solar reflectance and a temperature drop of up to 25 °C, outperforming commercial counterparts. A purple radiative cooling paint (mixed dyes) demonstrates the color customization potential within the CMYK space, addressing the dilemma between color and cooling for colored radiative cooling paints. The mechanical and surface properties, characterized by abrasion, adhesion, and contact angle tests, are on par with or surpassing commercial products. This unique self-stratifying mechanism enhances surface properties and provides new insights for developing high-volume loading paints and water-harvesting coatings without increasing fabrication complexity.
尽管被动式日间辐射冷却具有显著的节能潜力，促使人们采用漫反射白色或反射性表面，但实现彩色化可拓展其在美学和功能方面的应用。然而，这在可扩展加工方面带来了巨大的技术挑战。本文提出了一种新颖且通用的自分层方法，使用选定的窄带吸收染料来制备具有各种颜色的辐射冷却涂料。这些涂料作为单层涂层应用时，会自组装成吸收 - 散射双层结构，既能有效呈现颜色，又能将光吸收降至最低。实验证明，三种基色（青色、品红色和黄色）可实现全天低于环境温度的冷却效果，太阳能反射率达到93%，天空窗口发射率为0.94。一种新研发的黑色涂料太阳能反射率达到46.3%，温度降幅高达25°C，性能优于市售同类产品。一种紫色辐射冷却涂料（混合染料）展示了在CMYK色彩空间内进行颜色定制的潜力，解决了彩色辐射冷却涂料在颜色与冷却性能之间的两难问题。通过磨损、附着力和接触角测试表征的机械性能和表面性能与市售产品相当或更优。这种独特的自分层机制增强了表面性能，为开发高负载量涂料和集水涂层提供了新的思路，同时不增加制造复杂性。
