As-prepared Superhydrophobic Surface Research Articles

Superhydrophobic copper surface with mechanical, chemical, and UV durability along with corrosion resistance and self-cleaning effect

It is the prerequisite of improving the universality, stability, and wear resistance of superhydrophobic materials for the practical applications. A simple and environment-friendly method is developed herein for constructing superhydrophobic copper surface by hydrothermal method. The wettability, surface microstructure, phase structure, and chemical structure of superhydrophobic Cu2S-coated copper surface are examined by contact angle measurement, SEM observation, XRD measurement, FT-IR and EDS analyses. Results show that the superhydrophobic Cu2S-coated copper surface is composed of a large number of Cu2S crystals grafted with long hydrophobic alkyl chains, and which leads to the superhydrophobic copper presenting a rough and hierarchical surface with micro- and nano-scaled binary structure. It is noteworthy that 200 °C of heat treatment has marked influence on the surface microstructure and wettability. Consequently, the mechanical durability of the superhydrophobic copper has been improved greatly upon heat treatment. Just ground on both the hierarchical surface and grafted long hydrophobic alkyl chains as well as heat treatment, the as-prepared superhydrophobic copper surface exhibits not only good mechanical durability and corrosion resistance, but also excellent chemical and UV durability as well as self-cleaning effect. This method provides a novel and simple process to protect the surface of copper. It is believed that such technique may open a new approach to expand the application of copper. A simple and environment-friendly method is developed for constructing superhydrophobic copper surface by hydrothermal method. Ground on both the hierarchical surface and grafted long hydrophobic alkyl chains as well as heat treatment, the as-prepared superhydrophobic surface exhibits not only good mechanical durability and corrosion resistance, but also excellent chemical and UV durability as well as self-cleaning effect.

Superhydrophobic surface on aeronautical materials via the deposition of nanoparticles and a PDMS seal

This paper reports a stable superhydrophobic surface on resin composites through the coprecipitation process of hydroxyethyl cellulose and modified Zn-particles, subsequently with the use of PDMS seal. Surface morphologies and chemical compositions are investigated with SEM, EDS, and FT-IR. As expected, the prepared surface has the water repellency with the contact angle of 153° and the sliding angle of 1°, respectively. According to the comparison of different specimens when after the liquid impingement test, it can be reasonably demonstrated that appropriate PDMS seal improves the stability with regard to superhydrophobic surfaces. When superhydrophobic surface is soaked chronically and impinged strongly by water, its water repellency is going to reduce. However, further surface modification introduced by combustion leads to excellent water repellency again. And the sliding angle value of further modified surface is below 1°. The preparation of superhydrophobic surface is also applicable to a paper. This superhydrophobic paper is less flammable than the untreated paper. In addition, the as-prepared superhydrophobic surface exhibits good self-cleaning ability towards avoiding different types of contaminants.

Understanding the anti-icing property of nanostructured superhydrophobic aluminum surface during glaze ice accretion

Ice accumulation on power transmission lines has been a vital problem for power systems in cold regions. In this paper, the anti-icing property of the as-prepared superhydrophobic (SHP) surface on the aluminum substrate in glaze ice was studied in an artificial climate chamber. Results show that the as-prepared SHP surface demonstrates excellent anti-icing property with only 24.65% of the entire surface froze after spraying for 60 min. The nano-scale structures and the HDTMS molecule both contributed to the superhydrophobicity. The reason for the excellent anti-icing property of the as-prepared SHP surface can be ascribed to two reasons: on the one hand, the nanoscale structures can effectively help maintain the superhydrophobicity of the as-prepared SHP surface at low temperatures, which inhibited the frosting process for over 210 min at −5°C and −10 °C. On the other hand, the as-prepared SHP surface can completely repel the impacting millimeter-level cooled water droplets or reducing the critical diameter of micro-scale droplets in glaze ice leading to a reduction of ice accumulation. The nanostructured ZnO textures significantly helped improve the ability to resist frost and ice accumulation on the aluminum surface, which has a good prospect on power transmission lines against ice formation.

One-Step Preparation of Durable Super-Hydrophobic MSR/SiO₂ Coatings by Suspension Air Spraying.

In this study, we develop a facial one-step approach to prepare durable super-hydrophobic coatings on glass surfaces. The hydrophobic characteristics, corrosive liquid resistance, and mechanical durability of the super-hydrophobic surface are presented. The as-prepared super-hydrophobic surface exhibits a water contact angle (WCA) of 157.2° and contact angle hysteresis of 2.3°. Mico/nano hierarchical structures and elements of silicon and fluorine is observed on super-hydrophobic surfaces. The adhesion strength and hardness of the surface are determined to be 1st level and 4H, respectively. The coating is, thus, capable of maintaining super-hydrophobic state after sand grinding with a load of 200 g and wear distances of 700 mm. The rough surface retained after severe mechanical abrasion observed by atomic force microscope (AFM) microscopically proves the durable origin of the super-hydrophobic coating. Results demonstrate the feasibility of production of the durable super-hydrophobic coating via enhancing its adhesion strength and surface hardness.

Facile fluorine-free one step fabrication of superhydrophobic aluminum surface towards self-cleaning and marine anticorrosion

Service performance and safety of aluminum materials are restricted by the proneness to marine corrosion. The facile and low cost fabrication of fluorine-free superhydrophobic aluminum surfaces for anticorrosion is still a challenging issue. Herein, we report a handy and versatile fabrication of nonfluorinated Allium giganteum-like superhydrophobic aluminum surfaces via one step electrodeposition approach. The surface topographies, wettability and chemical compositions were detailed characterized and discussed. In addition, we investigated the self-cleaning and low surface adhesion ability of the as-fabricated electrodeposited superhydrophobic surface. The electrochemical impedance spectra was performed to reveal the corrosion resistance and inhibition efficiency of the as-prepared superhydrophobic surface. The air-exposure and 3.5 wt% NaCl immersion tests suggest a good lasting quality of the surface. We believe the facile fabrication of fluorine-free superhydrophobic surface can meliorate many shortcomings of achieving superhydrophobicity and broaden the potential applications of aluminum-based materials towards marine-related fields.

A Simple, Low-cost Method to Fabricate Drag-reducing Coatings on a Macroscopic Model Ship

A low-cost method was used to fabricate superhydrophobic coatings on a macroscopic model ship and the drag-reducing effect was investigated at both low and high speed. Hierarchical structures of the superhydrophobic copper coatings were characterized by means of scanning electron microscopy(SEM) and X-ray diffraction(XRD). Drag coefficient tests on surfaces with different wettability(superhydrophilic, hydrophilic, hydrophobic and superhydrophobic surfaces) showed that the as-prepared superhydrophobic surface exhibited a high remarkable drag reduction of 81% at a low speed of 1 mm/s. In the drag-reducing tests with model ship, the superhydrophobic coatings also exhibited around 16% drag reduction at a velocity of 0.3 m/s.

A biomimetic surface with switchable contact angle and adhesion for transfer and storage of microdroplets.

Recently, superhydrophobic surfaces with switchable wettability have attracted much attention. The ability to control the contact angle and adhesion of the multifunctional smart surface will be more beneficial to meet the complex practical applications, but until now this has been a challenge. Inspired by rose petals, we report a smart, biomimetic, and superhydrophobic surface whose wettability can switch reversibly between superhydrophobicity and superhydrophilicity on the Cu substance. At the same time, we can control the adhesion on the as-prepared superhydrophobic surface by covering and removing the ink. Thus, the as-prepared surface can be used as a medium for microdroplet transfer and storage. Compared with the original Cu substrate, electrochemical measurements show that the corrosion inhibition of the superhydrophobic surface is significantly improved. Good corrosion resistance allows the platform to be used to manipulate or store more types of microdroplets, especially corrosive microdroplets. In addition, the as-prepared surface has a good stability which facilitates the practical application of the as-prepared smart surface. This work provides a smart and effective strategy for lossless transfer and patterned storage of microdroplets. It is also promising for the design of new smart interface materials such as for biological cell manipulation, chemical microreaction and other types of microfluidic devices.

A novel dissolution and resolidification method for preparing robust superhydrophobic polystyrene/silica composite

The poor robustness under large pressure has become the bottleneck for the practical applications of the superhydrophobic surfaces. Here, we present a simple and inexpensive method for forming a superhydrophobic surface using polystyrene and an acetone based suspension of perfluorosilane-coated silica nanoparticles. The acetone is a suitable solvent to dissolve the PS which tends to form microscale roughness. Simultaneously, the nanoparticles are forced to get embedded into the PS surface during the resolidification process after evaporating the acetone. The combination of partially-embedded nanoparticles and hierarchical structure result in the robustness of as-prepared surface, which could withstand tape-peeling test (24.50kPa) for at least 80 times and sandpaper abrasion (7.84kPa) for 6.75m without losing superhydrophobicity. Moreover, the as-prepared superhydrophobic surface maintains excellent self-cleaning properties in either air or oil environment.

One-step hydrothermal process to fabricate superhydrophobic surface on magnesium alloy with enhanced corrosion resistance and self-cleaning performance

Superhydrophobic surfaces can exhibit anti-corrosion, anti-fogging, and self-cleaning performance due to their high water repellence. It is significant for industrial fabricating of superhydrophobic surface with a simple and environment-friendly method. Herein, a facile, environment-friendly, and cost-effective one-step hydrothermal route is proposed to fabricate the superhydrophobic surface on magnesium alloy. The as-prepared superhydrophobic magnesium alloy surface presents the rough and hierarchical micro/nano- structure grafted with long hydrophobic alkyl chains via covalent bonds. Both electrochemical corrosion test and long term immersion in 3.5wt.% of NaCl solution demonstrate that the superhydrophobic surface greatly improves the corrosion resistance of magnesium alloy. Meanwhile, the superhydrophobic magnesium alloy exhibits excellent self-cleaning performance. It is supposed that this facile method and remarkable properties of resultant superhydrophobic magnesium alloys have a promising future in expanding the application of magnesium alloys.

Novel, stable and durable superhydrophobic film on glass prepared by RF magnetron sputtering

A novel and facile approach has been adopted to fabricate a nanostructured superhydrophobic (SHP) film on glass by radio frequency (RF) magnetron sputtering. The surface morphology, XRD pattern, chemical composition and wettability were analyzed by corresponding methods. It was found that the as-prepared SHP surface exhibited a prominent superhydrophobicity with a contact angle (CA) up to 168.9° and sliding angle less than 1°, which was mainly attributed to the low surface energy of hexadecyltrimethoxy silane and Al2O3-ZnO (mass ratio (Al/Zn)≈1:1.2) nanofibers along with the presence of high proportions of micro/nano air pockets induced by a hierarchical composite network. Moreover, the as-prepared SHP surface demonstrated good stability under outdoor and ambient environment, and retained its superhydrophobicity even at severe temperatures as well as in strong corrosive surroundings.

Electrohydrodynamic behavior of water droplets on a horizontal super hydrophobic surface and its self-cleaning application

Moisture is a significant factor that affects the insulation performance of outdoor high-voltage insulators in power systems. Accumulation of water droplets on insulators causes severe problems such as flashover of insulators and power outage. In this study, we develop a method to fabricate a micro/nano hierarchical super hydrophobic surface. The as-prepared super hydrophobic surface exhibits a water contact angle (WCA) of 160.4±2°, slide angle (SA) less than 1° and surface free energy (SFE) of 5.99mJ/m2. We investigated the electrohydropdynamic behavior of water droplet on a horizontal super hydrophobic surface compared with hydrophobic RTV silicone rubber surface which was widely used as anti-pollution coating or shed material of composite insulator. Results show that water droplet tended to a self-propelled motion on the super hydrophobic surface while it tended to elongate and break up on the RTV surface. The micro/nano hierarchical surface structure and chemical components with low surface free energy of the super hydrophobic surface jointly contributed to the reduction of skin fraction drag and subsequently made it possible for the motion of water droplet driven by electric field. Furthermore, the self-propelled motion of water droplets could also sweep away contaminations along its moving trace, which provides super hydrophobic surface a promising anti-pollution prospect in power systems.

Superhydrophobic Anodized Fe Surface Modified with Fluoroalkylsilane for Application in LiBr–Water Absorption Refrigeration Process

LiBr refrigerating systems are frequently used in industry, but the pipelines are easily corroded or blocked by the LiBr solution with high flow resistance. Here, a superhydrophobic Fe surface was proposed and tested for applicability. After constructing a rough Fe2O3 nanotube array on a Fe surface by the anodization process, a superhydrophobic Fe surface was obtained by silane modification. The as-prepared superhydrophobic surface exhibited excellent repulsion to LiBr solutions. The modified Fe foil showed a 3.35% decrease in thermal conductivity but a 99.2% improvement of anticorrosion protection efficiency. LiBr crystals deposited on this surface were easily detached. The flow resistance along the superhydrophobic surface was reduced to 50% of that along a pure Fe surface. The operation temperature of the system was broadened due to low blockage risk. The excellent thermal conductivity, anticorrosivity, drag reduction, and antifouling performance of the superhydrophobic Fe surface exhibits promise for ...

Fabrication of Self-Cleaning and Anti-Icing Durable Surface on Glass

Ice accumulation on insulators affected the safety of power system and may inflict serious consequences such as insulator flashover accidents and power failure. This article reported a simple method to prepare anti-icing polydimethylsiloxane superhydrophobic surface on glass by utilizing nano-particle filling method. The effect of concentration of silica nanoparticles on superhydrophobicity of the samples was investigated. The wettability, surface morphology and anti-icing property of the as-prepared superhydrophobic surface were characterized by corresponding methods. Results show that the as-prepared surface with addition amount of 7 g silica nanoparticles exhibited self-cleaning property and excellent superhydrophobicity with a contact angle of 165.7 ± 2.4° and a sliding angle of 3.8°. It was found that the ice formation was delayed for 29 min at −5 °C. Moreover, the as-prepared superhydrophobic surface showed superhydrophobicity in the pH range of 1–13 and exhibited excellent drop impact stability. The as-prepared superhydrophobic surface may be suitable for applications in cold regions owing to its flexibility, durability and anti-icing property.

A cost-effective method for preparing mechanically stable anti-corrosive superhydrophobic coating based on electrochemically exfoliated graphene

Electrochemical exfoliation of graphite has been presented to be an effective method to prepare graphene, but its application in superhydrophobic coating is still rare. Here, we reported a simple and facile method to prepare superhydrophobic surfaces via painting the mixture of electrochemically exfoliated graphene and polydimethylsiloxane. The as-prepared superhydrophobic surface exhibited excellent self-cleaning property. Moreover, the superhydrophobic surface showed much smaller corrosion current density, reduced 8868-fold from the bare Al 6061 substrate. Furthermore, this superhydrophobic surface possessed good mechanical stability due to the fact that the surface could maintain superhydrophobicity after water-impact and sand-impact tests. This method may open a new avenue in the design and fabrication of superhydrophobic surfaces with self-cleaning and anticorrosive property.

Water transport control on a patterned superhydrophobic surface via laser direct writing

A simple method for fabricating line patterns on a superhydrophobic surface is demonstrated using nanosecond laser direct writing. A laser-induced superhydrophobic surfaces exhibit the excellent superhydrophobicity with a contact angle of 158° and a sliding angle of less than 5°. By changing the superhydrophilic linewidth and line intervals, the authors investigated the anisotropic wetting and adhesive properties on the as-prepared line-patterned superhydrophobic surface. The experimental results showed that the linewidth and line intervals have an important influence in anisotropic wetting, including contact angles and sliding angles in both parallel and perpendicular directions. This data allow control of adhesion by having droplets slide off at designated tilting angles on the patterned superhydrophobic surface. The water droplet array can be easily separated into any configuration, such as an upper triangular array. The as-prepared patterned superhydrophobic surface can transfer different microliter-sized droplets from one superhydrophobic surface to another. This patterned superhydrophobic surface has some potential applications for the droplet manipulation, microfluidic devices, and cell culture.

Facile and scalable preparation of highly wear-resistance superhydrophobic surface on wood substrates using silica nanoparticles modified by VTES

In this study, an efficient, facile method has been developed for fabricating superhydrophobic surfaces on wood substrates using silica nanoparticles modified by VTES. The as-prepared superhydrophobic wood surface had a water contact angle of 154° and water slide angle close to 0°. Simultaneously, this superhydrophobic wood showed highly durable and robust wear resistance when having undergone a long period of sandpaper abrasion or being scratched by a knife. Even under extreme conditions of boiling water, the superhydrophobicity of the as-prepared wood composite was preserved. Characterizations by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy showed that a typical and tough hierarchical micro/nanostructure was created on the wood substrate and vinyltriethoxysilane contributed to preventing the agglomeration of silica nanoparticles and serving as low-surface-free-energy substances. This superhydrophobic wood was easy to fabricate, mechanically resistant and exhibited long-term stability. Therefore, it is considered to be of significant importance in the industrial production of functional wood, especially for outdoor applications.

One-step solve-thermal process for the construction of anticorrosion bionic superhydrophobic surfaces on magnesium alloy

Superhydrophobic surface with biomimetic micro/nanostructures was prepared in this study. The mammillaria-herrerae-like microspheres, carnation-like microclusters and carnation-petal-like nano-slices of biomimetic micro/nanostructures on magnesium alloy surface can create a stable superhydrophobic surface, which is similar to the “lotus leaf” structure. The as-prepared superhydrophobic surface had a contact angle of 158.5° and a sliding angle of 2.0°. Potentiodynamic polarization measurements demonstrated that the superhydrophobic surface greatly improved the corrosion properties of magnesium alloy in 3.5wt% NaCl solution.

Durable, self-cleaning and superhydrophobic bamboo timber surfaces based on TiO2 films combined with fluoroalkylsilane

Decorative materials, including bamboo timber, have been proposed to exploit their superhydrophobic and self-cleaning properties, but a comprehensive appraisal of their environmental adaptability is still deficient. In this paper, a robust and durable superhydrophobic surface was formed on bamboo timber substrate through a process combining chemical solution deposition and chemical modification. The superhydrophobic surface resulted from micro-nanoscale binary-structured TiO2 films and the assembly of low-surface-energy fluorinated components, which exhibited a water contact angle of 163±1° and a sliding angle of 3±1°. The surface maintained superhydrophobicity after mechanical abrasion against 1500 mesh SiC sandpaper for 800mm at the applied pressure of 1.2kPa, indicating good mechanical stability. Moreover, the superhydrophobic surface exhibited good chemical stability against both acidic and basic aqueous solutions (e.g., simulated acid rain). After exposure to atmosphere for more than 180 days, the obtained surface still maintained a contact angle of 155±2° and a sliding angle of 6±2°, revealing good long-term stability. In addition, the as-prepared superhydrophobic surface exhibited almost complete wet self-cleaning of dirt particles with water droplets. It is believed that the method presented in this study can provide a straightforward and effective route to fabricate a large-area, mechanically robust, anticorrosive and self-cleaning superhydrophobic surface on woody materials for a great number of potential applications.

Facile fabrication of iron-based superhydrophobic surfaces via electric corrosion without bath

Superhydrophobic surface is of wide application in the field of catalysis, lubrication, waterproof, biomedical materials, etc. The superhydrophobic surface based on hard metal is worth further study due to its advantages of high strength and wear resistance. This paper investigates the fabrication techniques towards superhydrophobic surface on carbon steel substrate via electric corrosion and studies the properties of as-prepared superhydrophobic surface. The hydrophobic properties were characterized by a water sliding angle (SA) and a water contact angle (CA) measured by the Surface tension instrument. A Scanning electron microscope was used to analyze the structure of the corrosion surface. The surface compositions were characterized by an Energy Dispersive Spectrum. The Electrochemical workstation was used to measure its anti-corrosion property. The anti-icing performance was characterized by a steam-freezing test in Environmental testing chamber. The SiC sandpaper and 500g weight were used to test the friction property. The research result shows that the superhydrophobic surface can be successfully fabricated by electrocorrosion on carbon steel substrate under appropriate process; the contact angle of the as-prepared superhydrophobic surface can be up to 152±0.5°, and the sliding angle is 1–2°; its anti-corrosion property, anti-icing performance and the friction property all show an excellent level. This method provides the possibility of industrialization of superhydrophobic surface based on iron substrate as it can prepare massive superhydrophobic surface quickly.

A rapid one-step process for the construction of corrosion-resistant bionic superhydrophobic surfaces

Abstract A simple, one-step method has been developed to construct a corrosion-resistant bionic superhydrophobic surfaces by solve-thermal process in an ethanol and water solution containing stearic acid. Superhydrophobic surface with biomimetic micronanostructures was prepared in this study. The Mammillaria herrerae-like microspheres, carnation-like microclusters and carnation-petal-like nanoslices of biomimetic micronanostructures on magnesium alloy surface can create a stable superhydrophobic surface, which is similar to the “lotus leaf” structure. The as-prepared superhydrophobic surface had a contact angle of 158.5° and a sliding angle of 2.0°. The as-prepared superhydrophobic surfaces were characterized by means of scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and contact angle measurement. Potentiodynamic polarization measurements demonstrated that the superhydrophobic surface greatly improved the corrosion properties of magnesium alloy in 3.5 wt% NaCl solution.