Stable Superhydrophilic Surface Research Articles

Determining the Role of Oxygen in Obtaining Long-Term Stable Superhydrophilic Surfaces on Metals Treated with a Femtosecond Laser.

Laser processing is a simple way to obtain hydrophobic or even superhydrophobic properties of metal surfaces. However, preparation of superhydrophilic surfaces by this method, the properties of which do not change under the influence of various factors, remains a difficult task. In this work, we show that with increasing laser power, the degree of oxidation of the treated metal surface also increases. As a result, highly oxidized samples showed highly stable superhydrophilic properties. A Janus membrane fabricated from a stainless steel mesh with asymmetric hydrophilic-hydrophobic wettability demonstrated stable water diode properties. In addition, it was found that during the examination of sample surfaces by Raman spectroscopy, organic compounds adsorbed on the hydrophobic surface were decomposed by the laser of the spectrometer, which imposes limitations on the laser power when using this method in characterizing hydrophobic surfaces of metals fabricated by laser processing.

Rapid laser fabrication of long-term stable superhydrophilic aluminum surface

A simple method for fabricating stable superhydrophilic aluminum surface is reported in this paper. Controllable micro-nanostructures were prepared on the surface of aluminum plate by nanosecond laser and then soaked in boiled 45% ethanol solution for 2 h as the post-treatment. It is demonstrated that the laser-ablated aluminum plate surface is hydrophilic and then switch to superhydrophilic after a 45% ethanol solution post-treatment. The treated superhydrophilic structure has good hydrophilic stability in a certain period of time. The mechanism of superhydrophilic behavior of aluminum surface treated with laser and ethanol solution was discussed. A new method for preparing stable superhydrophilic surface is proposed in this paper, which is of great significance for the preparation of superhydrophilic surface and the application of superhydrophilic surface in industrial production.

Effect of Nanosecond Laser Treatment Parameters on Surface Wettability Behaviour of Pure Aluminium

In this study, a method of preparing stable superhydrophilic surface on aluminum plate by nanosecond laser is presented. The influences of different laser processing parameters on the wettability of aluminum plate and the effect of preservation temperature on the conversion rate of aluminum plate from superhydrophilic to superhydrophobic after laser ablation were studied. It is demonstrated that the microstructure formed by different laser processing parameters has certain influence on the hydrophilic property of aluminum plate, such as the lower the scanning interval and scanning speed, the easier it is to form a superhydrophilic surface. In addition, the storage temperature has a significant effect on the change of surface contact angle with time. The samples stored in the average temperature of 0°C in the atmospheric environment have an average contact angle of 18.7 °in 60 day after laser treatment, which has always maintained a good hydrophilicity. However, the samples heated 3 hours in the temperature of 150 °C appears the hydrophobicity with an average contact angle of 156.3 The mechanism of wettability transition was expounded, and a method to maintain the superhydrophilic durability of metal surface was proposed in this paper.

In situ growth of hierarchical Al2O3 nanostructures onto TiO2 nanofibers surface: super-hydrophilicity, efficient oil/water separation and dye-removal

Developing a facile strategy to synthesize template-free TiO2 membrane with stable super-hydrophilic surface is still a daunting challenge. In this work, super-hydrophilicity (close to 0°) and underwater super-oleophobicity (165°) have been successfully demonstrated on a hierarchical Al2O3/TiO2 membrane, which is prepared via a facile electrospinning method followed by simple calcination in air. The precisely-tuned Al2O3 heterojunctions grew in situ and dispersed uniformly on the TiO2 surface, resulting in an ‘island in the sea’ configuration. Such a unique feature allows not only achieving super-hydrophilicity by maximizing the surface roughness and enhancing the hydrogen bonding, but also improving the adsorption capacity toward different toxic dyes utilizing the abundant adsorption sites protected by the hierarchical nanostructure during sintering. The new Al2O3/TiO2 nanofibrous membrane can serve as a novel filter for gravity driven oil/water separation along with dye removal, achieving 97.7% of oil/water separation efficiency and 98% of dye capture, thanks to their superb wettability and the sophisticated adsorptive performance. Our presented fabrication strategy can be extended to a wide range of ceramic materials and inspires their advanced applications in water purification under harsh liquid-phase environments.

Production of stable superhydrophilic surfaces on 316L steel by simultaneous laser texturing and SiO2 deposition

Superhydrophilic surfaces with liquid contact angles of less than 5° have attracted much interest in practical applications including self-cleaning, cell manipulation, adhesion enhancement, anti-fogging, fluid flow control and evaporative cooling. Standard laser metal texturing method often result in unstable wetting characteristics, i.e. changing from super hydrophilic to hydrophobic in a few days or weeks. In this paper, a simple one step method is reported for fabricating a stable superhydrophilic metallic surface that lasted for at least 6 months. Here, 316L stainless steel substrates were textured using a nanosecond laser with in-situ SiO2 deposition. Morphology and chemistry of laser-textured surfaces were characterised using SEM, XRD, XPS and an optical 3D profiler. Static wettability analysis was carried out over a period of 6 months after the laser treatment. The effect of surface roughness on wettability was also studied. Results showed that the wettability of the textured surfaces could be controlled by changing the scanning speed of laser beam and number of passes. The main reason for the realisation of the stable superhydrophilic surface is the combination of the melted glass particles mainly Si and O with that of stainless steel in the micro-textured patterns. This study presents a useful method of fabricating stable superhydrophilic surfaces on metals.

Fabrication of metallic surfaces with long-term superhydrophilic property using one-stop laser method

Abstract A simple method for fabricating stable superhydrophilic surface at metallic substrates is reported. This technique comprises irradiating the surface with multiple laser pulses. Surface wettability can be taylored through controlling laser parameters and processing conditions. The substrates were selected as aluminum alloy and stainless steel. Physical morphology and chemical composition of laser-textured surfaces were characterized by SEM, XPS, and 3D profiler measurements. Results showed that the longest wettability duration was achieved as more than 1 month for stainless steel and more than 200 h for Al alloy, respectively. The possible mechanism of hydrophilic behavior of laser-textured surfaces was discussed. The effect of surface topography on superhydrophilicity property was also evaluated. This study presents a promising method in fabricating long-term superhydrophilic surfaces, which is useful for improving adhesion or achieving water-assisted flow in industrial applications as well as developing cell-based technologies in biomedical applications.

Fabrication of stable superhydrophilic surfaces on titanium substrates

We report a method of producing superhydrophilic surfaces on titanium substrates via sandblasting and dip-coating with colloidal silica nanoparticles. The surface exhibits a high level of hydrophilic stability, as it stays superhydrophilic for an excess of 40 days and through multiple wetting–dewetting cycles. The combination of microscale roughness from the sandblasting and nanoscale roughness from the silica particles results in a micro-nano binary structure, which greatly enhances the hydrophilicity of the titanium samples. Due to the simplicity and ease of implementation of this method, such a surface is suitable for potential use in a variety of applications, such as prosthetic dentistry and other biomedical fields.

Production of a superhydrophilic surface by aluminum-induced crystallization ofamorphous silicon

The wettability of glass substrates textured via aluminum-induced crystallization(AIC) of amorphous silicon (a-Si) was studied. It was found that a stablesuperhydrophilic surface could be produced by AIC of a-Si. This research suggeststhat densely distributed micron-sized silicon islands with nanoscale siliconspikes produced by the technique of AIC of a-Si are responsible for the stablesuperhydrophilicity. The study also shows that these superhydrophilic surfacescan be easily converted to superhydrophobic ones by means of coating withC4F8.