Sustainable cellulose foams for all-weather high-performance radiative cooling and building insulation

Yunfei Bai; Xiaohua Jia; Zhiqiang Shan; Caiyue Huang; Ding Wang; Jin Yang; Bo Pang; Haojie Song

doi:10.1016/j.carbpol.2024.121951

Sustainable cellulose foams for all-weather high-performance radiative cooling and building insulation

Carbohydr Polym. 2024 Jun 1:333:121951. doi: 10.1016/j.carbpol.2024.121951. Epub 2024 Feb 15.

Authors

Yunfei Bai¹, Xiaohua Jia², Zhiqiang Shan¹, Caiyue Huang¹, Ding Wang¹, Jin Yang¹, Bo Pang³, Haojie Song⁴

Affiliations

¹ School of Materials Science & Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, PR China.
² School of Materials Science & Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, PR China. Electronic address: xhjia2003@126.com.
³ Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrheniusväg 16C, Stockholm 106 91, Sweden. Electronic address: bo.pang@mmk.su.se.
⁴ School of Materials Science & Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, PR China. Electronic address: songhaojie@sust.edu.cn.

PMID: 38494216
DOI: 10.1016/j.carbpol.2024.121951

Abstract

Passive daytime radiative cooling (PDRC) as a zero-energy-consumption cooling technique offers rich opportunities in reducing global energy consumption and mitigating CO₂ emissions. Developing high-performance PDRC coolers with practical applicability based on sustainable materials is of great significance, but remains a big challenge. Herein, polyvinyl alcohol (PVA) and esterified cellulose (EC) extracted from sawdust were used as raw materials to construct foams by using a dual-crosslinking assisted-unidirectional freeze-drying strategy followed by hydrophobic surface modification. The resultant PVA/EC (PEC) foams with ideal hierarchical macropore structure displayed various excellent features, such as low thermal conductivity (26.2 mW·m^-1·K^-1), high solar reflectance (95 %) and infrared emissivity (0.97), superhydrophobicity as well as high mechanical properties. The features allowed the PEC foams to be used as radiative coolers with excellent PDRC performance and thermal insulating materials. A maximum sub-ambient temperature drops of 10.2 °C could be achieved for optimal PEC foams. Building simulations indicated that PEC foams could save 55.8 % of the energy consumption for Xi'an. Our work would give inspiration for designing various types of PDRC coolers, including but certainly not limited to foams-based radiative coolers.

Keywords: Foams; Freeze-drying; Radiative cooling; Sawdust; Thermal-insulating.