Preparation Of Superhydrophobic Surfaces Research Articles

A new route for the preparation of superhydrophobic surfaces via milling operation

A new route for the preparation of superhydrophobic surfaces via milling operation

Atmospheric plasma etching of polymers: A palette of applications in cleaning/ashing, pattern formation, nanotexturing and superhydrophobic surface fabrication

Atmospheric Pressure Plasmas (APPs) are promising alternatives to their low-pressure counterparts for material surface treatment due to their potential for cost-effective continuous processing. Here we present for the first time to our knowledge a palette of applications of polymer etching showing the potential of APPs for cleaning/ashing, nanopattern formation, nanotexturing, and hierarchical superhydrophobic surface fabrication using the same plasma source configuration. First, we used a dielectric barrier discharge (DBD) plasma source to study etching/cleaning/ashing of different polymers such as PMMA films and AZ photoresist with lithographic patterns using He/O2 mixtures. We achieved high-rate, uniform etching, indicating the source potential for cleaning/ashing even in ambient air conditions. We have noticed that thick photoresist films are damaged after prolonged etching in air plasmas, a phenomenon resembling photoresist damage observed during low-pressure plasma etching. Second, we applied colloidal lithography with polystyrene (PS) nanoparticles followed by isotropic APP etching in order to form nanopatterns on both Silicon and Polymers. We observed that APP induces “cauliflower-like” nanotexturing of the PS spheres. This nanotexturing in combination with plasma etching of the underlying polymer and the spheres allow the fabrication of hierarchical surfaces. Optimization of plasma etching duration (i.e. hierarchical topography) followed by low-pressure plasma deposition of a low surface energy fluorocarbon (hydrophobic) coating led to the preparation of superhydrophobic surfaces with water contact angle 158° and hysteresis 9° (roll-off behavior).

The research on preparation of superhydrophobic surfaces of pure copper by hydrothermal method and its corrosion resistance

In this paper, a novel method combining etching and hydrothermal treatment was used to design the superhydrophobic surface on the copper substrates. The contact angle of the superhydrophobic surface was 157.7 ± 1°. The superhydrophobic surface showed the corrosion inhibition efficiency of 99.81% in 3.5 wt% NaCl aqueous solution. Besides, the superhydrophobic surface showed a good stability in simulated seawater and humid air. In addition, the formation mechanism of copper superhydrophobic surface was analyzed based on the results of SEM, XRD and XPS.

Superhydrophobic surfaces: a review on fundamentals, applications, and challenges

Superhydrophobicity is the tendency of a surface to repel water drops. A surface is qualified as a superhydrophobic surface only if the surface possesses a high apparent contact angle (>150°), low contact angle hysteresis (<10°), low sliding angle (<5°) and high stability of Cassie model state. Efforts have been made to mimic the superhydrophobicity found in nature (for example, lotus leaf), so that artificial superhydrophobic surfaces could be prepared for a variety of applications. Due to their versatile use in many applications, such as water-resistant surfaces, antifogging surfaces, anti-icing surfaces, anticorrosion surfaces etc., many methods have been developed to fabricate them. In this article, the fundamental principles of superhydrophobicity, some of the recent works in the preparation of superhydrophobic surfaces, their potential applications, and the challenges confronted in their new applications are reviewed and discussed.

Preparation of superhydrophobic surfaces with micro/nano alumina molds.

Polymer micro/nano hierarchical structures were successfully formed by photo-nanoimprinting using anodic porous alumina molds. Anodic porous alumina molds with hierarchical structures were prepared by the anodization of an Al substrate with a micro-concave array. The obtained surfaces with hierarchical structures exhibited superhydrophobicity. The hydrophobic properties of the obtained samples were dependent on the surface structures and could be optimized by changing the micro- and nanopatterns in the hierarchical structure.

Comparative Study on Wettability of Typical Plant Leaves and Biomimetic Preparation of Superhydrophobic Surface of Aluminum Alloy

The water droplets spread observation, contact angle measurement and SEM analysis, data processing and other means, comparative study of different states of the lotus leaf, rice leaf and nasturtium leaf are carried out. The results show that their surface contact angle of three kinds of plant leaves are all over 140°, they have hydrophobic or superhydrophobic properties; dehydration degree of leaves has little effect on the wettability, will not change its hydrophobic property; the same point of wettability is that they have micro nano composite microstructure. The difference is, the wettability of the lotus and nasturtium is isotropic, while the rice is anisotropic, that is, in a direction parallel to the edge of hydrophobic than perpendicular to the blade edge enhancement. Based on the theoretical research, the hydrophobic surface is copied to the surface of aluminum alloy. The superhydrophobic surface of aluminum alloy matrix was successfully prepared by chemical etching combined with surface fluorination. The super hydrophobic aluminum alloy surface has micron-nano scale double roughness structure; its surface contact angle reached 156°.

Comparative Study on Wettability of Typical Plant Leaves and Biomimetic Preparation of Superhydrophobic Surface of Aluminum Alloy

The water droplets spread observation, contact angle measurement and SEM analysis, data processing and other means, comparative study of different states of the lotus leaf, rice leaf and nasturtium leaf are carried out. The results show that their surface contact angle of three kinds of plant leaves are all over 140°, they have hydrophobic or superhydrophobic properties; dehydration degree of leaves has little effect on the wettability, will not change its hydrophobic property; the same point of wettability is that they have micro nano composite microstructure. The difference is, the wettability of the lotus and nasturtium is isotropic, while the rice is anisotropic, that is, in a direction parallel to the edge of hydrophobic than perpendicular to the blade edge enhancement. Based on the theoretical research, the hydrophobic surface is copied to the surface of aluminum alloy. The superhydrophobic surface of aluminum alloy matrix was successfully prepared by chemical etching combined with surface fluorination. The super hydrophobic aluminum alloy surface has micron-nano scale double roughness structure; its surface contact angle reached 156°.

Fabrication of anisotropic PTFE superhydrophobic surfaces using laser microprocessing and their self-cleaning and anti-icing behavior

Due to excellent stability and intrinsic low surface energy, polytetrafluoroethylene(PTFE) is widely utilized to fabricate biomimetic superhydrophobic surfaces. We proposed a facile and rapid method to obtain outstanding superhydrophobic surfaces by CO2 laser microprocessing PTFE plate. Scanning electron microscope(SEM) and contact angle measuring instrument were employed to characterize the structure and wettability. The effects of different micro channels spacing, different processing times and different processing power on wettability and morphology were studied. The self-cleaning and anti-icing properties of the prepared PTFE superhydrophobic surface were investigated. It was demonstrated that the maximum static contact angle was up to 168.36°. The degree of anisotropy could be controlled by adjusting the micro channels spacing. The as-prepared PTFE superhydrophobic surfaces exhibited self-cleaning properties, and water droplets were easy to take away dusts attached to the surfaces. Especially, it was found using the self-made icing monitoring system that as-prepared PTFE superhydrophobic surface showed an outstanding dynamic anti-icing performance even if the surface temperature was as low as −25°C and surrounded by ice and frost. The present study therefore suggests that CO2 laser microprocessing could be applied to large-scale preparation of superhydrophobic surface for practical applications in different fields of self-cleaning, anti-icing, microfluidic devices, lab-on-chips system, directional water harvesting, drag reduction and other fields.

Multiple Liquid Manipulations on Patterned Surfaces with Tunable Adhesive Property

AbstractMicro/nanostructured surfaces with designable wettability show great promise in many fields. This paper reports a new strategy for fabricating superhydrophobic surfaces with tunable water adhesion force by combining multiscale surface structures and mussel‐inspired surface chemistry, which can be used for multiple liquid manipulations. Highly ordered porous films prepared by the breath figure method enable convenient construction of surfaces with honeycomb‐patterned or nanosized pincushion‐like structures. Multiple liquid manipulations including no‐loss transportation of water droplets, water collection, programmable movement of water droplets, and chemical reaction monitoring are demonstrated on the micro/nanostructured surfaces. The proposed method is facile, energy‐efficient, and can be conducted for the preparation of superhydrophobic surfaces with high contrast adhesion patterns.

Mussel-inspired chemistry for preparation of superhydrophobic surfaces on porous substrates

A facile and versatile mussel-inspired surface modification approach was used to fabricate a lotus-leaf-like hierarchical surface with superhydrophobicity.

Preparation of superhydrophobic surface via one-step photopolymerization

In this work, one superhydrophobic surface was facilely achieved by one-step photopolymerization of tridecafluorooctyl acrylate (G06C) with solvent. The superhydrophobic property was created by the combination of low surface energy material polytridecafluorooctyl acrylate and the rough structure created by the solvent evaporation. The roughness of polytridecafluorooctyl acrylate (PG06C) coating was determined by the content of solvent.

A novel combination approach for the preparation of superhydrophobic surface on copper and the consequent corrosion resistance

In this paper, superhydrophobic surfaces on copper substrates are prepared by combining the etching and calcination treatment processes. The surface morphologies, wettability, chemical composition and corrosion resistance are characterized by means of scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), water contact angle, potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The achieved superhydrophobic surface has a contact angle as high as 157.6° and a persistent corrosion resistance in a 3.5wt.% NaCl aqueous solution. This method could provide an effective route to fabricate superhydrophobic surface with inhibitive and self-cleaning properties for various applications.

Superhydrophobic qualities of an aluminum surface coated with hydrophobic solution NeverWet

Effortless preparation of superhydrophobic surfaces mimicking the wetting characteristics of lotus leaf is of interest to several works. Spray coating methods using hydrophobic solutions are often adopted to realize such superhydrophobic surfaces. The present study investigates the dynamic behavior of impacting water drops on an aluminum surface coated with commercially available hydrophobic solution NeverWet with primary focus to understand the superhydrophobic qualities of the coated surface. The Weber number, We of impacting drop was varied from 1 to 568. The salient features of drop impact dynamics are compared with those of other superhydrophobic surfaces and naturally seen lotus leaf reported in literature. The outcomes as well as the bounce-off characteristics of impacting water drops are comparable to those observed on lotus leaf. The contact time remains almost constant with impact velocity, U-0 for 7 < We < 200. The dynamics of impacting water drops on the coated surface is compared with published works on superhydrophobic surfaces prepared using other fabrication methods. The trend of maximum lamella spread factor with We on the coated surface could be predicted using the analytical relation developed for drop impact on small target surfaces ignoring the effect of viscosity. The power dependence of maximum spread factor on We is higher if fingers at the rim of lamella are accounted for in the maximum spread measurements. The number of fingers formed at the rim of lamella at its maximum spread for high We drop impact increases with We which follows the predictions from Rayleigh-Taylor and a modified Savart-Plateau-Rayleigh instability as well as experimental data reported in literature. The findings from the study are useful for works which use NeverWet to develop superhydrophobic qualities on solid surfaces. (C) 2016 Elsevier B.V. All rights reserved.

Hierarchical micro/nano-structured nanoimprinting stamp fabrication for superhydrophobic application

ABSTRACTThe hierarchical micro/nano structure of a real lotus leaf was successfully transferred to a nickel stamp, and it was used as a nanoimprinting stamp for superhydrophobic surface preparation. The hierarchical micro-bump/nano-tubule structure of the lotus leaf was transformed to a nano-wrinkled micro-bump in order to apply the nanoimprinting process and provide superhydrophobicity. Ag nanoparticles (AgNPs) were uniformly coated over the lotus leaf surface to form an electrically conducting seed layer, followed by a nickel electroplating process. A nickel stamp with a well-defined negative structure of a lotus leaf, including even nano-wrinkled microstructure, was thereby successfully fabricated. The micro/nano pattern of the lotus leaf was successfully reduplicated on a poly vinyl chloride (PVC) film by a nanoimprinting process using the nickel stamp. According to contact angle measurements, the nanoimprinted polymer films are rendered hydrophobic. Superhydrophobicity was then obtained by applying a self-assembled monolayers (SAM) coating over the nanoimprinted polymer film.

Facile preparation of superhydrophobic candle soot coating and its wettability under condensation

A facile method was developed to prepare a superhydrophobic candle soot coating by burning candle and simple deposition on a low-density polyethylene substrate. The water contact angle and sliding angle of the as-prepared superhydrophobic candle soot coating were, respectively, 160 ± 2° and 1° under common condition. ESEM images showed that the superhydrophobic candle soot coating was comprised of many nanoparticles with the size range of about 30–50 nm. After condensation for 30 min, the average contact angle of the condensed water droplets was 150° ± 2°, showing excellent superhydrophobicity under condensation. The mechanism of the candle soot coating remaining superhydrophobicity under condensation was analyzed. This work is helpful for the design and preparation of superhydrophobic surface which can remain superhydrophobicity in future.

Preparation of Superhydrophobic Surface Based on SiC Particulate Reinforced Composite

Micro- and nano-structures were prepared based on SiC particulate reinforced composite substrate using electrochemical etching process, and effects of current density and etching time on morphology characteristics and superhydrophobicity of the etched surfaces were investigated. The results show that a special hierarchical structure consisting of particle-shaped microstructures and nano-structrues (particle- or squama-shaped) is formed on the etched SiC/Al composite at the current density of 6 A/dm 2 , which keeps almost unchanged during etching period. Under optimized process conditions, superhydrophobic surface can be obtained, achieving a water contact angle of up to 160.7° and an extremely small tilting angle of 4°. All these data demonstrate that SiC/Al composite has poten- tial to be used as self-cleaning surface.

PVP-assisted Synthesis of TiO2Nanospheres and their Application to the Preparation of Superhydrophobic Surfaces

Enhancement of the surface hydrophobicity of polydimethylsiloxane (PDMS) thin films deposited on substrates covered with titanium dioxide (<TEX>$TiO_2$</TEX>) nanospheres was studied. First, a low-temperature solution-phase method using polyvinylpyrrolidone (PVP) as a surface capping agent and a water/dimethylformamide (DMF) mixture as the reaction medium was used to synthesize monodisperse <TEX>$TiO_2$</TEX> nanospheres. It was possible to easily control hydrolysis rate of the Ti-precursors and the size of the synthesized nanospheres by varying the amount of PVP and the volume ratio of the solvent mixture. Spray coating of the synthesized <TEX>$TiO_2$</TEX> nanospheres under the PDMS film increased the water contact angle of the film surface to <TEX>$150.3^{\circ}$</TEX>. This simple treatment can modify the surface morphology at a nanometer scale without any long or complicated nanoprocess; hence, the surface enters the superhydrophobic Cassie-Baxter regime.

유기용매에 의한 실리카 나노입자의 응집조절과 비불소계 자기조립박막을 이용한 초발수 표면 제조

유기용매에 의한 실리카 나노입자의 응집조절과 비불소계 자기조립박막을 이용한 초발수 표면 제조

Fabrication and Characterization of Superhydrophobic Poly(vinylidene fluoride-co- hexafluoropropylene)/TiO2 Nanocomposite Coating for Corrosion Protection Applications

Superhydrophobic surfaces have a strong potential for implementation in variety of fields, including self-cleaning surfaces, biomedical and coatings for corrosion protection. Preparation of superhydrophobic surfaces requires both an optimum roughness and low surface energy; therefore, these surfaces are conventionally prepared employing two steps: roughening a surface and lowering its surface energy. In this study, the superhydrophobic Poly(vinylidene fluoride-co-hexafluoropropylene)/TiO2 nanocomposite coatings were fabricated using a simple one-step coating method on a carbon steel substrate to study the corrosion behavior in harsh environments. The surface wettability and morphology of the prepared coatings were characterized using the sessile droplet method and scanning electron microscopy, respectively. X-ray photoelectron spectroscopy and X-ray diffractometer were used to identify the elemental composition and chemical oxidation states of the prepared surface. The surface roughness of the coatings was measured using atomic force microscope. The chemical stability of the prepared coatings was inspected by immersion the specimens in different pH solutions. The results showed that stable superhydrophobic surfaces with high water contact angle and low contact angle hysteresis can be fabricated on the carbon steel surface. As well as, the corrosion resistant performance of the produced superhydrophobic surface on carbon steel was carried out by electrochemical impedance spectroscopy (EIS) measurements and potentiodynamic polarization in 3.5 wt % NaCl solution. The electrochemical corrosion tests revealed that the as-prepared superhydrophobic surface significantly improved the corrosion resistant of the C-steel substrate.

Fabrication of superhydrophobic surface with controlled adhesion by designing heterogeneous chemical composition

In this paper, a simple method for fabricating tunable adhesion superhydrophobic surface based on heterogeneous chemical composition was reported. By simply changing the ratio of HOOC(CH2)8COOH in the mixed modification solution, the slide angles (SA) of water droplet can be adjusted from extremely low (less than 10°) to very high (180°). Besides, the influence of surface chemical composition on the surface adhesion was also examined. Noticeably, the anti-corrosion performance of magnesium alloy was greatly improved after being modified. In addition, the tunable adhesion superhydrophobic magnesium alloy showed high hydrophobicity not only for pure water but also for corrosive liquids, such as acid, alkali, salt, cola, milk and coffee. Based on the great anti-corrosion performance and continuous adhesion, a proof of droplet-based microreactor and selective transportation of waters with different volume was provided. This study provides a new method for preparation of superhydrophobic surfaces with tunable adhesion, which not only offers the further principle for the fabrication of tunable adhesive superhydrophobic surfaces, but also can be potentially used in many important applications, such as micro-fluidic devices and chemical microreactors.