Papers by Keyword: Hydrophobic Surface

Abstract: Economically viable and maintenance free glass surfaces with improved hydrophobicity are highly demanding in the recent nanotechnology era. Deposition of pollutants and dirt on glass surface that not only causes visual obscurity but also damages the cultural heritages are still to be researched intensely. It is documented that excellent hydrophobic surfaces (with contact angle greater than 90^o) can be achieved by controlling the surface wettability, where liquid droplets remain spherical on such surfaces. Selection of materials and the preparation method play a significant role towards such accomplishments. Stirred by this idea, we explored the feasibility of fabricating super-hydrophobic tellurite glass systems by facilely varying the compositions of different constituents. Highly transparent and thermally stable ternary tellurite glass system with chemical composition of (80-x)TeO₂ – xSiO₂ – 20ZnO, where x = 0.00 to 0.20 mol% are synthesized via conventional melt-quenching method. Samples are characterized using Atomic Force Microscopy (AFM) and contact angle measurements. The impact of SiO₂ concentrations variation on the surface roughness, surface energy, and hydrophobic properties are inspected. Glass surface roughness as much as 9.885 nm is attained. The optimal value of water contact angle is discerned to be 101.02° for 0.1 mol% of SiO₂ incorporation into the amorphous tellurite host matrix. Besides, the surface energy revealed an inverse proportionality to the water contact angle. This achieved contact angle (greater than 90°) makes this hydrophobic glass surface beneficial for diverse applications. It is established that the present glass composition may be prospective for the development of super-hydrophobic surfaces.

Abstract: A simple and economical route based on a ZnCl₂ mediated process was developed to synthesize hierarchical flower-like ZnO micro/nanoflakes on the surface of copper foil by 2 stages electrodeposition method (2M ZnCl₂ – 0.5M ZnCl₂). The prepared flakes were characterized by XRD and SEM. The morphology of ZnO can be tuned from simple isolated nanoflakes to ordered flower-like shape using this method. The surfaces retain good hydrophobic stability in long period time.

Abstract: In recent years, a lot of effort has gone into many researchers making components of specific functions, mimicking various microstructures in nature. In this study, a super hydrophobic surface on injection-molded liquid silicone rubber was fabricated, mimicking micro-bumps on a lotus leaf. Original patterns were machined by electric discharge machining and liquid silicone rubber was injection-molded by using the original patterns as molds. The hydrophobic characteristics of injection-molded liquid silicone rubber surface replicated from the original electric discharge machined surface were studied. According to variations of injection molding process parameters like mold temperature, injection speed, injection pressure, vacuum, etc. the variations of water contact angles, as a hydrophobic index, measured on the injection-molded surfaces were examined. The liquid silicone rubber surface molded from wire-cutting electric discharge machined surface at mold temperature 120°C, injection speed 5 mm/sec, injection pressure 70 bar and in a vacuum cavity showed water contact angle of 148°, which is close to super-hydrophobic level.

Abstract: The high reactivity of the free silicon surface and its consequence: the “omnipresent” native silicon dioxide hinders the interface engineering in many processing steps of IC technology on atomic level. Methods known to eliminate the native oxide need in most cases vacuum processing. They frequently deteriorate the atomic flatness of the silicon. Hydrogen passivation by a proper DHF (diluted HF) treatment removes the native silicon oxide without roughening the surface while simultaneously maintains a “quasi oxide free” surface in a neutral or vacuum ambient for short time. Under such circumstances the last thermal desorption peak of hydrogen is activated at around 480-500°C where the free silicon surface suddenly becomes extremely reactive. In this study we show that deuterium passivation is a promising technology. Due to the fact that deuterium adsorbs more strongly on Si surface than hydrogen even at room temperature, deuterium passivation does not need vacuum processing and it ensures a robust process flow.