Preparation of a temperature-sensitive superhydrophobic self-cleaning SiO2-TiO2@PDMS coating with photocatalytic activity

Abstract In this paper, SiO2-TiO2 composite particles were prepared by loading nano-TiO2 onto the surfaces of amorphous SiO2 microspheres, which were then modified with PDMS to obtain a SiO2-TiO2@PDMS ternary compound. The photocatalytic performance of SiO2-TiO2@PDMS and the wettability of the coated surface were tested and characterized. Moreover, the effect of microstructure and composition of SiO2-TiO2@PDMS on its properties was studied. The results showed that SiO2-TiO2@PDMS possessed a certain degree of photocatalytic activity and the coating was almost superhydrophobic. Furthermore, the wettability and adhesion to water droplets of the SiO2-TiO2@PDMS coating were affected by the heat-treatment temperature; the mechanism of the above phenomena was also analysed. Moreover, the as-prepared coating exhibited excellent repellent effects towards acid (pH = 2), alkaline (pH = 11), and organic dye droplets. A mechanically damaged coating maintained its liquid repellence, indicating that the good mechanical stability of the coating. The superhydrophobicity of the as-prepared coating did not decrease after UV irradiation for 8 h, illustrating that the as-prepared coating had a great UV irradiation resistance. In addition, the as-prepared coating was environmentally friendly and free of fluorides and is therefore suitable for practical applications.