Hydrophobic Modification of Glass Surface by Using Sol-Gel Synthesized Glass Powder as A Surface Roughness Promoter (original) (raw)
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Applied Surface Science, 2011
This study fabricated the large area and optically transparent superhydrophobic silica based films on glass surface with optimized hardness. A silane coupling agent, tetraethoxysilane (TEOS), effectively bonds silica particles onto the glass substrate. Desired surface roughness was obtained by adjusting nano silica particles concentration of the precursors prepared by the sol-gel process. Silica suspension was coated onto the glass substrate by the air brushing methods. This method can deposit a uniform, transparent coating on the glass substrate efficiently. Diluting the precursor by adding ethanol or a mixture of D.I. water and ethanol further improved the transmittance and superhydrophobicity efficiency. The results showed that as the silica particle concentration and the thickness of the coating were increased, the surface roughness was enhanced. Rougher surface displayed a higher superhydrophobicity and lower transmittance. Therefore, the concentration of silica particle, volume of coatings, and the ratio of ethanol and D.I. water are of great importance to deposit a transparent, superhydrophobic coating on glass.
Progress in Organic Coatings, 2019
A sol-gel coating using colloidal silica on a glass surface is carried out towards improving the self-cleaning properties. The optical transmittance and hydrophobic characteristics of the resulting coating are analyzed using analytical tools. Since the sol-gel coating reduces the optical transmittance of the glass samples, due to scattering and diffusion of the incident optical radiation at the coating surface, silicon oil (Sigma-Aldrich, 10 cSt) impregnation method is introduced to improve the optical transmittance. Silicon oil has good heat transfer characteristics, stable properties over range of temperatures, and optically transparent characteristics with refractive index of 1.4034. The resulting coated surface is tested in outdoor environments to examine the dust effect on the optical transmittance of the sol-gel coated and oil impregnated glass samples. It is found that deposition of 75 nm size silica particles on the glass surface modifies the texture height of the sol-gel coating, which in turn, improves the surface hydrophobicity. Sol-gel coating results in a web-type fully connected porous structures; in which case, agglomeration of the synthesized particles is responsible for the fully connected porous texture at the coating surface. The optical transmittance remains low for the sol-gel coated glass samples because of scattering and diffusion of the incident optical radiation at the coating surface. Silicon oil impregnation improves the optical transmittance of the sol-gel coated samples. The dust particles immerse into the oil film and reduce the optical transmittance of the oil impregnated samples in outdoor environments.
Engineering and Technology Journal, 2021
The sol-gel-prepared silica incorporated into the RTV matrix demonstrated the optimal hydrophobic surface at contact angle 146°. Zeta potential analysis demonstrated the stability of nanoparticles at recorded average values of −41 to −50 mV. Some XRD peak intensities of hydrophobic coating (RTV silicone rubber/silica) coated glass differed from the neat component (RTV or silica). XRD differences between the neat materials and their corresponding composite demonstrate satisfactory incorporation and a cohesive layer that produced significant bonding between components. This works aims to investigate the influence of three different categories of silica, namely, precipitated silica, fumed silica and nanosilica prepared via solgel process, for hydrophobic application in this work. Nanosilica was characterised using scanning electron microscopy, Fourier transform infrared spectroscopy, particle size and zeta potential. Diluted silicone rubber (roomtemperature vulcanising silicone...
Hydrophobic Material: Effect of Alkyl Chain Length on the Surface Roughness
Journal of Manufacturing and Materials Processing
The clean technologies of self-cleaning surfaces are expanding rapidly. Highly hydrophobic coatings with strong adhesion, high durability, and dirt-free surfaces have been prepared via sol-gel deposition of SiO2-TiO2-alkylsilane. The influence of the effects of the alkyl chain length of silane on surface roughness was investigated. This deposition involved a one-layer technique to produce the rough surfaces. The bimetal oxide of SiO2-TiO2 created a high level of surface roughness. As a result, the water contact angle of the coatings increased with the increasing alkyl chain length of silane (up to C=8). However, the water contact angle decreased when the C=16 of alkylsilane was applied. It was predicted that the longer alkyl chain would cause the molecules to collapse. The higher hydrophobicity was produced by SiO2-TiO2-OTMS coatings with a water contact angle of about 140.67 ± 1.23°. The effect of the dip-coating technique (one layer and layer-by-layer) on hydrophobicity was also d...
Glass Spheres: Functionalization, Surface Modification and Mechanical Properties
Advanced Structured Materials, 2013
Hydrophobic micro-glass particles were obtained by chemical modification with organosilanes. Particles were treated by peroxymonosulfuric acid to obtain a hydrophilic surface, which was the first step of the modification process. Different silanes were used, each of them with a different functional group, effecting variable degrees of hydrophobicity. The successful chemical modification process was established using Fourier transform infrared spectroscopy (FTIR) and water drop interaction with the modified particles surfaces. The morphology of the modified particles was studied using scanning electron microscope (SEM). The degree of the hydrophobicity was established with static contact angle measurements. The microscopic adhesion and particle contact properties of the comparatively stiff (amorphous) micro-glass beads and the macroscopic powder flow behavior were investigated with ring shear tests and evaluated by constitutive models on physical basis.
Preparation and microstructure study of borosilicate coatings produced by sol-gel
Journal of Sol-Gel Science and Technology, 1994
Borosilicate coatings in the systems (100-x)SiO2-xB203 (x = 20, 30) and 75SiO2-20B203-5Na20 have been obtained using the dip-coating procedure. Stable solutions were prepared from TEOS and trimethylborate, H20/TEOS ratios being changed from 2 to 6. Sodium acetate in aqueous solution was used as Na20 precursor. Coatings were prepared in an airtight glove-chamber with humidity and temperature control. Good and transparent films were obtained only for RH < 20%. Microstructure evolution and phase separation phenomena were investigated by TEM studying their dependence on the water content of the solution, temperature and time of the heat treatment and thickness of the coatings. A comparison with similar melted glasses and bulk glasses prepared by sol-gel has been also established.
Synthesis and characterization of hydrophilic nanocomposite coating on glass substrate
Journal of Applied Polymer Science, 2006
Hydrophilic coatings based on 3-glicidoxy propyl trimethoxy silane (GPTMS) and polyethylene glycol (PEG) were prepared with the incorporation of tetramethoxysilane (TMOS) and silica nanoparticle colloidal suspension by a sol–gel process. Characterization of the coatings has been performed by Fourier Transform Infrared (FTIR) and Attenuated Total Reflectance Infrared (ATR-IR) techniques. Morphological properties were characterized by Scanning Electron Microscopy (SEM). The distribution of Si atoms in the hybrid system was obtained by Si mapping. The particle size in sol solution of the coating was measured by light scattering analyzer. Optical properties were characterized by using UV–vis spectrophotometer. The hydrophilicity of the coating was determined by contact angle measurements, and also the results have been confirmed by surface energy and water uptake investigations. The obtained results indicate that the surfactants affected the contact angles remarkably but did not change ...
Hydrophobic and oleophobic sol-gel coatings on glass substrates for usage at high temperatures
International Journal of Applied Glass Science, 2018
The paper reports an optimized process to obtain transparent and highly hydrophobic sol-gel coatings with further oleophobic behavior at high temperatures. Polyorganosiloxane sols were prepared incorporating an organic based precursor, 1H,1H,2H,2H Perfluorooctyltriethoxysilane (POTS), into a silica-based hybrid sol and deposited on soda-lime glass-slides. The coating surfaces show high water contact angle (WCA) around 120 AE 1°and oil contact angle (OCA) of 70 AE 1°after curing at temperatures between 350 and 400°C. The coatings thickness changed between 300 and 2000 nm depending on sol composition and curing temperature. Easy-to-clean tests were performed, the results showing excellent anti-stick and easy-to-clean properties compared to non-coated samples. Atomic force microscopy (AFM) revealed the presence of rippled surfaces with morphology similar to "lotus leaf surface," this explaining the properties. These hybrid fluoroalkylsilane sol-gel coatings are a good alternative to provide antistick and easy-to-clean properties to glass substrates being quite easy to scale up.