Fabrication of transparent and high durable superhydrophobic glass surfaces by one-step spray coating method

Superhydrophobic surfaces are known as surfaces with water contact angles above 150º and low sliding angles. Although superhydrophobic surfaces are of great interest in the industrial applications due to their non-wetting and self-cleaning properties, they still cannot be used extensively in industry due to low transmittance and low durability. Especially, to achieve durable superhydrophobic glass surfaces with high transmittance by easy-to-apply methods such as spray coating is still the one of most common problems both for industrial applications and in the literature. The aim of this thesis is to fabricate facile, transparent and durable superhydrophobic glass surfaces by one-step spray coating method, which can be applied to large areas affordable without advanced fabrication methods. There are two main points to achieve superhydrophobic surfaces. The first one is to increase the surface micro-nano roughness and the second one is to decrease the surface energy. Therefore, in this thesis, spherical silica nanoparticles (Si NPs) were used to increase surface roughness, and in order to reduce surface energy, ODTS and PDMS were employed. In the first part of the study, silica nanoparticles of different sizes were synthesized by using the Stöber method. The size of the synthesized silica nanoparticles was varied by changing the amount of the precursor chemicals such as NH4OH, DIW, and TEOS. Also, the effect of centrifugation and drying processes on the agglomeration mechanism of on silica nanoparticles have been studied in detail. In the second part of the thesis, the light transmittance, water contact angle and sliding angle of glass surfaces sprayed with solutions of different sized silica nanoparticles were examined. Furthermore, the light transmittance, water sliding and contact angles of glass surfaces that were fabricated by spraying different amounts of silane-modified silica nanoparticle solutions were investigated. In the last part of the thesis, PDMS/Si NPs based glass samples were fabricated. By varying the weight percent of silica nanoparticles in the spray solution and PDMS/Si NPs weight ratios in this solution, the change of the durability, light transmittance, water contact angle and sliding angle of the fabricated glass surfaces were examined. Our studies have shown for the first time in the literature that Si NPs with an average hydrodynamic diameter of 40 nm without any silane modification, when sprayed on glass surfaces in one step with dilute PDMS solutions, achieve light transmittance above %70, water contact angles over 160° and high durability to different abrasion tests. Keywords: Silica nanoparticle (Si NP), One-step spray coating, Trasnparent and high durable superhydrophobic glass surfaces, PDMS/Si NP glass surfaces