Preparation and Characterization of SiO2-PMMA and TiO2-SiO2-PMMA Composite Thick Films for Radiative Cooling Application

Abstract

Radiative cooling, an emerging technology that reflects sunlight and emits radiation into outer space, has gained much attention due to its energy-efficient nature and broad applicability in buildings, photovoltaic cells, and vehicles. This study focused on fabricating SiO2-polymethyl methacrylate (PMMA) and TiO2-SiO2-PMMA thick films via the blade-coating method. The investigation aimed to improve cooling performance by adding TiO2 particles to increase the coverage area and utilize the TiO2 reflectance ability. The characterizations of the emissivity/absorptivity, solar reflectance, and microstructure of the thick films were conducted by using ultraviolet–visible/near-infrared (UV-Vis/NIR) diffuse reflection spectroscopy and scanning electron microscopy, respectively. Experimental results revealed that the maximum temperature drops of approximately 9.4 and 9.8 °C were achieved during the daytime period for SiO2-PMMA and TiO2-SiO2-PMMA thick films. The total solar radiation reflectivity increased from 71.7 to 75.6% for SiO2-PMMA radiative cooling thick films after adding TiO2. These findings underscored the potential of TiO2-SiO2-PMMA thick films in advancing radiative cooling technology and cooling capabilities across various applications.