Tuning up sol-gel process to achieve highly durable superhydrophobic coating

Abstract

Considering practical application of hydrophobic coatings, their durability is a matter of issue. Existing routes for mitigating the problem might not be applicable due to suggesting expensive facilities and non-eco-friendly materials. This paper introduces a robust, scalable cost-effective sol-gel route to obtain a durable superhydrophobic coating. Main component of the sol included Tetraethyl orthosilicate and Methyltriethoxysilane as sol matrix, Triethoxyoctylsilane as a low surface energy precursor, and fumed silica nanoparticles for roughness formation. A coating with a contact angle of 160° and very low sliding angle (<1°) was fabricated. The robustness of the coating was highly improved by incorporating sols with different pH values and spraying them alternately on glass substrate. As a result, the longevity of superhydrophobic behavior doubled under accelerated weathering conditions and reached 1500 h, which could be considered as a promising weathering durability. The coating retained its hydrophobicity after three runs of peeling tape test and 26 min continuous slurry erosion. Regarding sol-gel technique, the research demonstrated how to boost the durability of a superhydrophobic coating by only utilizing chemical characteristics of the sols and incorporating available facilities with non-fluoro based materials. The reaction mechanisms during the sol-gel process and the effect of each component on final properties were thoroughly discussed and fundamentally correlated to the obtained results.