Preparation and Characterization of Biomimetic SiO2-TiO2-PDMS Composite Hydrophobic Coating with Self-Cleaning Properties for Wall Protection Applications

Abstract

Superhydrophobic surfaces have great potential for self-cleaning, anti-icing, and drag-reducing characteristics because of their water repellent property. This study demonstrates the potential application of coatings to protect architectures from detrimental atmospheric effects via a self-cleaning approach. In this research, a SiO2-TiO2-PDMS composite coating was prepared on the surface of building walls by the sol-gel method. Tetraethyl orthosilicate (TEOS) and titanium isopropoxide (TTIP) were used as inorganic precursors, and polydimethylsiloxane (PDMS) was used as low surface energy substances. The effects of TEOS and PDMS content on microstructure, wettability, and self-cleaning performance of coating wall surfaces were investigated by conducting various tests, including scanning electron microscopy (SEM), X-ray energy spectroscopy (EDS), angle measurement, and Fourier transform infrared spectroscopy (FTIR). The results indicated that hydrolysis and condensation reactions of TEOS, TTIP, and PDMS were performed on the surface of the substrates, leading to a micro- and nano-structure similar to the surface of lotus leaves. When the molar ratio of PDMS to TEOS was 1:5, the static contact angle of the coating reached a maximum of 152.6°. At this point, the coated surface was able to resist the adhesion of particle pollutants and liquid pollutants, which could keep the walls clean and possess a good ability of self-cleaning. In conclusion, SiO2-TiO2-PDMS composite coating is potentially useful in wall protection applications with its hydrophobic and environmentally friendly superhydrophobic properties.