Synthesis and characterization of hydrophobic coating materials based on alkoxy silane compounds

Recently, various methods have been developed for the preparation of hydrophilic surfaces such as wax solidification, lithography, electrochemical assemblies, hydrothermal, and sol-gel processes. Among these methods, sol-gel, which is the basis of chemical reactions in the solution, provides ground-level engineering for the researcher. In this study, a sol-gel-derived method for coating concrete substrates with a thin layer of a synthesized silica-based solution is presented. In this method, the tetraethyl orthosilicate compound is used as a precursor, octyltriethoxysilane, which has a large alkyl group, as modification agent and ethanol and methanol as solvent is used. Moreover, the effect of modifier agent on surface hydrophobic properties was investigated. The structure and morphology of synthesized solutions were described by infrared spectroscopy and atomic force microscopy images. Also, the contact angle of water, which indicates the surface hydrophobicity, was measured by the modifier agent in various ratios. The contact angle of the drop of water with the surface of hydrophobic concrete was about 141 degrees. Also, immersion test and water absorption for concrete specimens were prepared. For concrete, the amount of water absorption during 24 hours was 25 grams, while water absorption for hydrophobic concrete decreased to 9 grams. In another test, to investigate the effect of the synthesized solution on the actual samples, the hydrophobic effect followed by self-cleaning on samples of concrete and brick has been successfully carried out. According to the results of this study, the resulting hydrophobic solution can well boost the samples of concrete, stone, bricks, and any substrate based on silica. This synthesized solution, by creating an angle of drop of water up to 141 degrees, causes these surfaces to be hydrophobicity and self-cleaning effect.