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

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.