Waterborne polyurethane/cellulose composite aerogel with passive cooling and thermal insulation properties

Passive cooling is a cooling technology that does not require external energy input, with most passive cooling strategies having high manufacturing difficulty and cost. In this study, we prepared lightweight aerogels (0.093 g/cm3) with high porosity (91.3%), directional pores, enhanced elastic recovery performance, and lower thermal conductivity (0.046 W/mK) through simple mixing, directional freezing, and freeze-drying. The prepared samples have a reflectance of 87% in the ultraviolet-visible-near-infrared (UV-Vis-NIR) range (0.2-2.5 mu m) and an emissivity of 93.6% in the atmospheric transparency window. After covering the box with axial and transverse aerogel samples, the temperature inside the box relative to the uncovered sample box decreased by 12.9 and 13.4 degrees C, respectively. This work provides a feasible method for the research of simply prepared passive cooling materials. Mechanism and performance of Waterborne polyurethane/cellulose composite aerogel. image