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.

Preparation of a Stable Superhydrophobic Mortar Surface Using a One-Step Method

“…The configured methyl orange solution was placed on the superhydrophobic sample with a rubber-tipped dropper, and the process of pollutant flow was observed and photographed to record. 37 Stability Testing of Coating. Mechanical stability of the superhydrophobic coating was determined by sandpaper abrasion and tape peel experiments.…”

“…Liquid contaminants were simulated with methyl orange solution. The configured methyl orange solution was placed on the superhydrophobic sample with a rubber-tipped dropper, and the process of pollutant flow was observed and photographed to record …”

Synthesis of a water-based TEOS–PDMS sol–gel coating for hydrophobic cotton and polyester fabrics

“…40 An intense peak at around 1076 cm À1 to 1020 cm À1 indicates the presence of Si-O-Si bonds in the sample. 16 There is a medium intense peak at 889 cm À1 in the spectrum which is likely due to the asymmetric stretching of Si-C bonds. This peak is followed by a less intense peak at 857 cm À1 which is likely due to the symmetric stretching of Si-C bonds.…”

“…42 There is also an intense peak at 787 cm À1 which corresponds to CH 3 rocking in Si-CH 3 . 16,40 In the hydrolysed TEOS spectrum, there is a broad peak in the range of 3700-3200 cm À1 which indicates the vibration of O-H. Compared to the raw TEOS, the emergence of this peak shows that TEOS has been hydrolysed by water, and some Si-O-C bonds have been replaced by Si-O-H. 43 However, the existence of medium-intensity sharp peaks in the range of 3000-2800 cm À1 proves that there are still a few Si-O-C bonds that have not been hydrolysed in the solution, likely due to the fact that water is the limiting reactant in the hydrolysis process.…”

“…[13][14][15] Moreover, TEOS-PDMS coatings can be modified with various additives, such as nano-calcium oxalate, TiO 2 nanoparticles, and innovative antifouling silica nanocontainers, to improve their properties. [16][17][18] Other applications of TEOS-PDMS coatings include enhancing the lifetime of PDMS devices through sol-gel coatings.…”