Construction Of Hydrophobic Superhydrophobic Coating On SiO₂ Surface Of Silicate Glass

Superhydrophobic surface has a lot of advantages such as high water contact angle and low hysteresis, which could be applied into self-cleaning, anti-icing, oil-water separation and other areas. Many efforts have been taken to investigate the preparation methods and performances and made some progress, so how to fabricate large-scale superhydrophobic surfaces in a more convenient and high-efficient way has been the focus of recent researches. In this thesis, the transparent hydrophobic/superhydrophobic coating based on SiO₂ particles was fabricated on silicate glass according to the basic principle of "Lotus effect", and also its contact angle, transparency and stability performances were carefully investigated.The superhydrophobic surface was successfully dip-coated on silicate glass substrate by taking silica sol ?acidic silica sol, alkaline silica sol and silica sol mixture with three different stoichiometric ratios of acids and alkaline, respectively? as precursor solution and hexadecyltrimethoxysilane ?HDTMS? as modifying agent. The effects of acidic silica sol, alkaline silica sol and mixtures acidic and alkaline silica sol on wettability, hardness and stability of the hydrophobic coating were carefully studied. The surface morphologies of coatings were characterized by field-emission scanning electron microscopy ?FESEM? and the results showed that the hydrophobic property of alkaline silica sol was much better than the acidic silica sol coating, hardness performance on the contrary. When Vacid:Falkaine equals to 3:7, the silica nanoparticles in alkaline silica sol could link with each other effectively and form a good combination with the substrate at a certain strength and roughness, thus making silica sol mixture the best candidate for hydrophobic performances. In this case, the contact angle of coating is 128.2°, the transmittance of visible light is up to 95% and the hardness is no less than 6H. The hydrophobic coating could also exhibit good stability after exposure to natural light for 35 days or washed by water for 5 times.Taking TMCS modified SiO₂ ?dissolved in toluene? as the precursor solution, the superhydrophobic surface has been synthesized on silicate glass with a dip-coating method and its performances has been characterized by contact angle measurement, transmittance testing instrument, field-emission scanning electron microscopy ?FESEM? and energy dispersive X-ray spectrometers ?EDX?. The results indicated that the as-fabricated coating exhibited a lotus leaf-like micromorphology after immersing into precursor solution for three times. In addition, the water contact angle and slide angle of the superhydrophobic coatings were 156°±2° and 5°±1°, respectively and he transmittance in the visible region was above 75%, indicating an excellent self-cleaning performance; Moreover, the superhydrophobicity could still be maintained washed by water jet for five times. This convenient and simple preparation of superhydrophobic coating can provide a valuable reference for practical industrialization.