Polyvinyl alcohol/boron nitride aerogels for radiative cooling

• Published in: Journal of applied polymer science Vol. 141; no. 44
• Main Authors: Xu, Yazhou, Zhang, Jingna, Wang, Jingjing, Zhu, Huijie, Zhang, Shixun, Pan, Yamin, Liu, Xianhu, Liu, Chuntai, Shen, Changyu
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 20.11.2024; Wiley Subscription Services, Inc
• Subjects: aerogel; Aerogels; Ambient temperature; Boron nitride; Cooling; Daytime; poly (vinyl alcohol); Polyvinyl alcohol; radiative cooling; Sunlight; Thermal insulation
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.56174

Daytime radiative cooling material provides a low‐energy way of cooling because it can reflect sunlight and radiate heat without consuming any energy. However, there are still great difficulties in manufacturing low‐cost, high‐efficiency, sustainable, and biodegradable daytime radiative cooling materials. In this paper, poly (vinyl alcohol)/boron nitride (PVA/BN) composite aerogels were prepared by freeze‐drying technology. By adjusting the PVA concentration and BN content, the aerogel can achieve high sunlight reflectivity (96%), high mid‐infrared emissivity (96%) and good thermal insulation performance. Therefore, the temperature of the aerogel can be reduced to 12.5°C lower than the ambient temperature at night, and 5.5°C lower than the ambient temperature under the direct sunlight of 900 W/m2. This aerogel opens an environmentally sustainable pathway for radiative cooling applications. Poly (vinyl alcohol)/boron nitride composite aerogels with high sunlight reflectivity (96%), high mid‐infrared emissivity (96%), and good thermal insulation performance are prepared by freeze‐drying technology for radiative cooling. the temperature of the aerogel can be reduced to 5.5°C lower than the ambient temperature under the direct sunlight of 900 W/m2.