Development of Hydrophobic Non-Fluorine Sol-Gel Coatings on Aluminium Using Long Chain Alkyl Silane Precursor

Hydrophobic surface can be achieved by synergistic effect of lowering of surface energy and increase in surface roughness. Present work emphasizes on the development of thin hydrophobic sol-gel coatings on aluminium substrate using a long chain C-16 silane precursor i.e., Hexadecyltrimethoxysilane (HDTMS) crosslinked with Glycidoxypropyltrimethoxysilane (GPTMS) and Tetraethoxyorthosilcate (TEOS), in varying concentrations. Condensation and hydrolysis reactions of all three silane precursors resulted in hydrophobic sol-gel coating with a contact angle greater than 90. This can be attributed to the self assembled, low energy HDTMS groups on the surface. By further, enhancing the surface roughness of the aluminium substrate, before coating application, using various etching solutions, it was possible to achieve enhanced hydrophobicity with contact angle of about 130 and sliding angle of 20. Surface morphology, surface roughness and hydrophobicity of the coating were characterized using SEM, AFM and water contact angle analysis, respectively.