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Super‐hydrophobic surface has excellent waterproof, self‐cleaning and delayed icing properties, and is widely used in various fields, but its lack of durability restricts its large‐scale use. In this paper, carbon fiber composite material with excellent mechanical properties is selected as the substrate, PTFE nanoparticles with excellent hydrophobicity are used as the surface energy substance, and metal screen is selected as the template, combined with hot pressing molding process, a super‐hydrophobic surface with multi‐level micro‐nano structure is successfully constructed. The test shows that the water contact angle of the surface is 169°, and the rolling angle is about 2°. The contact angle of the surface is also over 150° for other liquids, and it bounces off the external water droplets for three times, so it can easily take away pollutants and keep the surface dry and clean under the action of water flow. In the same icing environment, compared with the original surface, it can prolong the freezing time of droplets by 5 times. After repeated rubbing, the surface still has superhydrophobic properties until the whole surface is completely destroyed. The preparation method used in this study is simple, and the prepared superhydrophobic surface has excellent performance, which is expected to promote the application of superhydrophobic surface in practical working conditions. Highlights: The preparation method is fast, efficient, low‐energy and environment‐friendly, and the used materials are simple and economical, and can be reused.The prepared surface has excellent hydrophobic performance for different media.The prepared superhydrophobic surface has low adhesion and droplet rebound performance.The prepared superhydrophobic surface has excellent delayed icing performance.The prepared superhydrophobic surface has excellent wear resistance. [ABSTRACT FROM AUTHOR]

Increased energy consumption, driven by climate change and the rise of new industries, has spurred a demand for alternative cooling technologies to replace energy‐intensive systems and mitigate environmental pollution. Radiative cooling, leveraging the optical properties of materials to cool without emitting pollutants or consuming energy, is considered a suitable solution. Among the various form of radiative cooling devices, paint stands out as a practical application for radiative cooling. Hence, a passive daytime radiative cooling (PDRC) paint is developed using a polyurethane binder and zeolitic imidazolate framework (ZIF)‐8. ZIF‐8 is synthesized in an environmentally friendly manner using deionized water as the solvent, resulting in paint with a reflectance of 94.9%, emissivity of 94%, and cooling power of 113 W m−2. Temperature measurements reveal that the paint reduced ambient temperatures by an average of 5.7 °C, reaching up to 8.1 °C during the day. Additionally, with a self‐assembly monolayer coating, the PDRC surface exhibited super‐hydrophobicity and self‐cleaning capabilities. Therefore, the proposed ZIF‐8‐based PDRC paint offers sub‐room temperature cooling potential and is anticipated to reduce energy consumption for cooling, thereby alleviating environmental pollution in various applications, particularly in building exteriors. [ABSTRACT FROM AUTHOR]

Indwelling medical catheters are frequently utilized in medical procedures, but they are highly susceptible to infection, posing a vital challenge for both health workers and patients. In this study, the superhydrophobic micro-nanostructure surface was constructed on the surface of thermoplastic polyurethane (TPU) membrane using heavy calcium carbonate (CaCO3) template. To decrease the surface free energy, hydroxyl silicone oil was grafted onto the surface, forming a super-hydrophobic surface. The water contact angle (WCA) increased from 91.1° to 143 ± 3° when the concentration of heavy calcium CaCO3 was 20% (weight-to-volume (w/v)). However, the increased WCA was unstable and tended to decrease over time. After grafting hydroxyl silicone oil, the WCA rose to 152.05 ± 1.62° and remained consistently high for a period of 30 min. Attenuated total reflection infrared spectroscopy (ATR-FTIR) analysis revealed a chemical crosslinking between silicone oil and the surface of TPU. Furthermore, Scanning electron microscope (SEM) image showed the presence of numerous nanoparticles on the micro surface. Atomic force microscope (AFM) testing indicated a significant improvement in surface roughness. This method of creating a hydrophobic surface demonstrated several advantages, including resistance to cell, bacterial, protein, and platelet adhesion and good biosecurity. Therefore, it holds promising potential for application in the development of TPU-based medical catheters with antibacterial properties. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Mechanics is the property of Chinese Journal of Applied Mechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Increased energy consumption, driven by climate change and the rise of new industries, has spurred a demand for alternative cooling technologies to replace energy‐intensive systems and mitigate environmental pollution. Radiative cooling, leveraging the optical properties of materials to cool without emitting pollutants or consuming energy, is considered a suitable solution. Among the various form of radiative cooling devices, paint stands out as a practical application for radiative cooling. Hence, a passive daytime radiative cooling (PDRC) paint is developed using a polyurethane binder and zeolitic imidazolate framework (ZIF)‐8. ZIF‐8 is synthesized in an environmentally friendly manner using deionized water as the solvent, resulting in paint with a reflectance of 94.9%, emissivity of 94%, and cooling power of 113 W m−2. Temperature measurements reveal that the paint reduced ambient temperatures by an average of 5.7 °C, reaching up to 8.1 °C during the day. Additionally, with a self‐assembly monolayer coating, the PDRC surface exhibited super‐hydrophobicity and self‐cleaning capabilities. Therefore, the proposed ZIF‐8‐based PDRC paint offers sub‐room temperature cooling potential and is anticipated to reduce energy consumption for cooling, thereby alleviating environmental pollution in various applications, particularly in building exteriors.

Super-hydrophobic surface (SHS), which traps micro/nano-scale gas bubbles on solid walls, has been reported to greatly reduce bacterial adhesion and biofouling. However, it is unclear whether and how the trapped gas bubbles reduce the bacterial adhesion. Here, we examine the role of the trapped gas on the bacterial adhesion by measuring the spatial distributions of attached bacteria on SHS using scanning electron microscopy (SEM). Two SHSs, one with regular micro-grooves, and the other with randomly roughed textures at micro/nano-scales, both created on aluminum substrates, were tested. We found that for a SHS where gas bubbles are trapped between roughness elements, bacteria only attach to the surface areas that are not covered by gas (e.g., top of roughness elements), while the areas covered by gas bubbles - gaps between roughness elements - are free of bacteria. In contrast, for a rough surface with the same texture geometry as that of SHS but no hydrophobic chemistry, bacteria are distributed evenly to the top and gap of roughness elements. Our results suggest that the SHS may reduce biofouling by providing a physical barrier of gas-liquid interface which separates bacteria from the solid walls. Furthermore, we showed that nano-scale roughness on SHS is insufficient to prevent bacterial adhesion. Our results should provide useful guidance for the future engineering design of efficient anti-biofouling materials.

[Display omitted] Porous surfaces of materials have shown huge potentialities for endowing materials with multifarious functions. Despite introducing gas-confined-barriers in supercritical CO 2 foaming technology is effective to weaken the gas escape effect and facilitate the preparation of porous surfaces, the differences in intrinsic properties between barriers and polymers result in bottlenecks like cell structure adjustment limitation and incompletely eliminated solid skin layers. This study undertakes a preparation approach for porous surfaces by foaming at incompletely healed polystyrene/polystyrene interfaces. In contrast with employing gas-confined-barriers reported before, the porous surfaces foamed at incompletely healed polymer/polymer interfaces show a monolayer, full-open cell morphology, and wide adjustable range in cell structures including cell size (120 nm∼15.68 μm), cell density (3.40 × 105 cells/cm2∼3.47 × 109 cells/cm2), and surface roughness (0.50 μm∼7.22 μm). Furthermore, the wettability of obtained porous surfaces depending on the cell structures is systematically discussed. Finally, a super-hydrophobic surface with hierarchical micro-nanoscale roughness, low water adhesion, and high water-impact resistance is built by depositing nanoparticles on a porous surface. Consequently, this study offers a clean and simple method to prepare porous surfaces with adjustable cell structures, which is expected to open a door to developing a new fabrication technique for micro/nano-porous surfaces. [ABSTRACT FROM AUTHOR]

A venous retention needle, as an implanted device, is very likely to cause thrombosis. In view of the thrombosis phenomenon caused by retention needles, this paper compares the influence of different superhydrophobic surface retentions on blood flow. Compared with other superhydrophobic bulges, the fluid velocity of the four-prism bulge is the highest (0.08 m/s), and the vorticity and shear force of the hemispherical bulge are higher. A large number of vortices can inhibit thrombosis better. The tire vortices generated in the superhydrophobic convex grooves are important vortices to inhibit thrombosis. The enhancement and development of the tire vortex weakens the resistance near the wall of the needle and reduces the probability of platelet aggregation. The superhydrophobic surface structure studied in this paper can not only provide guidance for the design of venous retention needles with better performance but also provide corresponding technical support for the development of human implantation devices. [ABSTRACT FROM AUTHOR]

The suitability of phyto-synthesized metal oxide nanoparticles for producing super-hydrophobic coatings for potential biomedical, agricultural and industrial applications was studied for the first time. ZrO2, CeO2 and SnO2 nanoparticles were synthesized through a green and facile method by using the aqueous leaf extract of the widely distributed Azadirachta indica as capping agent with over 60 % percentage mass yield. Organic groups acting as capping/stabilizing agents and siloxane attachments were identified using Fourier transform infra-red (FTIR). Tiny spherical ZrO2 nanoparticles, angular shaped CeO2 particles and a bed of tiny SnO2 particles with overall predominant particle sizes less than 15 nm were observed using field emission scanning electron microscope (FESEM). As expected, non-wettability of surfaces generally increased with increasing siloxane coupling of the nanoparticles. At a nanoparticle to fluoroalkylsilane mole ratio of 1:1, non-wettable, highly non-wettable and super-hydrophobic surfaces were obtained for CeO2, SnO2 and ZrO2 nanoparticles, respectively. The extent of initial phytochemical adsorption, size of the nanoparticles and extent of agglomeration are major factors that influence the coupling of fluoroalkylsilanes and consequently, the wettability of surfaces produced.

Super-hydrophobic surfaces have attracted much attention for their potential applications based on the lotus effect, especially in corrosion protection. However, the lotus effect has limited application given its high dependence on external forces, such as gravity and wind force. The self-propelled jumping behavior of water droplets, a newly found phenomenon over super-hydrophobic surfaces, would bring an alternative mechanism to atmospheric corrosion protection. Two different super-hydrophobic surfaces with a cone-shaped array microstructure and a flower-shaped hierarchical microstructure, respectively, were designed over copper substrate with an electrodeposition method. The dynamic growth and coalescence behavior of droplets were compared over the two super-hydrophobic surfaces. The cone-shaped array microstructure facilitates the self-jumping behavior of micro-droplets over the super-hydrophobic surface. In further, corrosion protection performance of the super-hydrophobic surfaces was examined after condensation in a simulated atmospheric environment. It was proven that the self-jumping behavior of micro-droplet helps remove the droplet over super-hydrophobic surfaces, thereby minimizing the likelihood of any subsequent corrosion behavior. This study demonstrates a novel corrosion protection mechanism for super-hydrophobic surfaces, and provides instructions for designing highly effective super-hydrophobic surfaces for corrosion protection.

The motion of droplets on a super-hydrophobic surface, whether by sliding or rolling, is a hot research topic. It affects the performance of super-hydrophobic materials in many industrial applications. In this study, a super-hydrophobic surface with a varied roughness is prepared by chemical-etching. The adhesive force of the advancing and receding contact angles for a droplet on a super-hydrophobic surface is characterized. The adhesive force increases with a decreased contact angle, and the minimum value is 0.0169 mN when the contact angle is 151.47°. At the same time, the motion of a droplet on the super-hydrophobic surface is investigated by using a high-speed camera and fluid software. The results show that the droplet rolls instead of sliding and the angular acceleration increases with an increased contact angle. The maximum value of the angular acceleration is 1,203.19 rad/s2 and this occurs when the contact angle is 151.47°. The relationship between the etching time, roughness, angular acceleration, and the adhesion force of the forward and backward contact angle are discussed. [ABSTRACT FROM AUTHOR]

Anode flooding is a critical issue in proton exchange membrane (PEM)-based electrochemical hydrogen pumps. Water-proofing the gas diffusion layer (GDL) on the anode side is a highly effective approach to mitigate the flooding problem and to enhance hydrogen pump performance. In this study, we report a low-cost, wet chemical process for water-proofing a metallic GDL. Silver particles, used as roughening and bonding agents, were first deposited on the porous metallic gas diffusion medium, and then heptadecafluoro-1-decanethiol (HDFT) was applied as a hydrophobic surface modifier. The result was a super-hydrophobic porous metallic GDL. Real electrochemical pump cell tests under simulated flooding conditions revealed that the water management performance of the coated GDL was dramatically improved.

Biological researches have attracted wide attentions in recent years, mimicking the morphology of creatures, learning the function of morphology and applying it to the engineering area have become the research focus. Investigating the special function of bionic surface texturing based on geometric morphology can provide us ideas to optimize surface properties of materials,extend the materials service life, widen the scope of application of materials, and improve the application values of materials. Through studying on the principle and application of hydrophobicity, bionic drag reduction, antifriction and wear-resistant due to the geometric morphology, the different functions of bionic texturing were explored, the future development directions of focusing on bionic patterns preparation and mechanism exploration were clarified, and further the surface treatment on materials was carried out to prepare the materials with more superior properties.

Super-hydrophobic (SH) surfaces mostly motivated by the primordial surface designs considerably increase the life of the substrate. In the present work, effort has been made towards rational development of the SH surface on ASTM A479 steels substrates coated with WC–10Co–4Cr using high-velocity oxy-fuel. Distinct coating configurations have been investigated to analyse the effect of circular texturing patterns using nanosecond laser fibre texturing machine for the development of SH surfaces. Here, a freshly prepared solution of Hexafor 644-D/PFOA/Al2O3 nanoparticles was utilized for simple HVLP spraying and dip coating methods to formulate SH coatings on untextured and textured surfaces. The developed SH surfaces were characterized by field emission scanning electron microscope, X-ray diffraction, energy-dispersive spectroscopy and surface roughness tester. Water repellency of fabricated SH surfaces and its durability were studied by measuring the water contact angle (WCA), sliding angle, sandpaper abrasion test, tape peeling tests and water impact tests. All the configurations of the developed SH surfaces were found to be sustainable against the different wear tests performed during the study and exhibited excellent repellence to water and ink droplets. The highest WCA and sliding angle for textured and dip-coated SH surface (configuration—C 2.1) were found to be 162.6° and 10°, respectively. Further, it was found that during the sandpaper abrasion test, and the configuration corresponding to textured surfaces after thermal spray coating sustained super-hydrophobicity up to 30 cycles. Because of simple steps and the desired properties obtained by proposed methods, the coatings may be used for producing SH surfaces in apt industrial applications. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Flow characteristics over a dynamic section of wind turbine blade in the presence of super-hydrophobic coatings were studied numerically using computational fluid dynamics method. Assuming a super-hydrophobic coating, blade icing can potentially be prevented. Fluids on super-hydrophobic surfaces are moving; so slip velocity exists on their walls. The dynamic motion was in sinusoidal mode that caused deep dynamic stall (DS) phenomenon. The occurrence of DS results in enlarged vortices with high strength of vorticity. These vortices cause overshoot in aerodynamic loads. By applying a super-hydrophobic surface on different locations of the airfoil, the DS vortex generation can be definitely affected. Investigation of these effects, is the aim of this paper. There is no study in the literature that analyzed DS in the presence of slip velocities at different locations. Thus, an SD7037 airfoil was simulated at R e ≈ 4 × 10 4 using Transition-SST model. Results demonstrated that as the coating covered the leading edge, DS and vortex formation were postponed and the lift peak reduced about 10.6%; while for airfoil entirely covered by coating, the maximum lift value was augmented 14.6% and DS delayed. Applying slip boundary conditions at trailing edge as well as the pressure side had not considerable changes in cyclic loads. • In cold climates, wind turbine blades may be iced; blade icing can dramatically reduce performance. • A water-repellant surface can potentially prevent atmospheric icing on the blades. • Dynamic stall is a limiting phenomenon for designing horizontal axis wind turbines. • Turbine blade performance in the presence of super-hydrophobic surfaces during dynamic stall occurrence analyzed. • The location of coating had different results for cyclic loads. At the pressure side, no noticable effects were observed. [ABSTRACT FROM AUTHOR]

Abstract Developing acid-resistant magnesium alloys is challenging because of the high chemical reactivity of magnesium in acidic media. In this work, a bio-inspired strategy by taking advantage of the super-hydrophobic effects on lotus leaves is described. The self-layered coating consisting of an inner compact layer and outer Mg-Al layered double hydroxide (LDH) microsheet-based layer prepared hydrothermally exhibits enhanced corrosion resistance in saline solutions but cannot resist corrosion in sulfuric acid. After depositing a fluorocarbon polymer film on the microsheets using a polytetrafluoroethylene (PTFE) target by magnetron sputtering, a super-hydrophobic surface is created on the magnesium alloy. Compared to the surface modified hydrothermally, the super-hydrophobic surface provides better corrosion protection in H 2 SO 4 due to trapped air pockets in the microsheet array. The dual process offers a promising means to mitigate corrosion of magnesium alloys in acidic media. Graphical abstract Unlabelled Image Highlights • A hydrothermal process produces a barrier with an inner compact layer and outer microsheet layer. • Magnetron sputtering with PTFE target is used to produce a polymer coating on the microsheets. • A super-hydrophobic surface in the Cassie state with a water contact angle of 170° is obtained. • The obtained surface exhibits dropwise water condensation and icing retardation behaviors. • The dual process yields better protection in H 2 SO 4 solutions than the hydrothermal method alone. [ABSTRACT FROM AUTHOR]

The carbon black (CB) used in rubber manufacturing and the unsafe disposal of agricultural waste are one of the causes of environmental pollution. Indeed, the production of one ton of CB produces about 2.4 tons of carbon dioxide. The conversion of these agricultural wastes into biochar (Bi) and using them as a reinforcing material is one of the trends that achieve sustainability and promote environmentally sound. Herein, the modified biochar (MBi) was obtained by chemo-mechanical treatment utilizing stearic acid for Bi which was produced from the pyrolysis of citrus trees to enhance its dispersion in nitrile butadiene rubber (NBR) composite. In addition, the present study scrutinized the influence of synergism between the MBi and CB as a filler in the NBR composites. The characterization of as-prepared samples was carried out by tracing the surface morphology, particle size analyzer, and identification of chemical bonds, as well as rheological, mechanical, aging, and electrical conductivity properties. The rheological studies showed that the optimum vulcanization time (tc90) did not significantly prolong for MBi-filled composites, which sequentially higher the benefits of the study by reducing energy consumed and thus, the process cost. In addition, the surface morphology and the mechanical data have distinguished that MBi particles were well-distributed along the matrix, as revealed by the tensile properties of the final composites. The electrical conductivity results manifested that MBi did not adversely affect the enhancement of conductivity. Whereas, the permittivity was increased due to the interfacial polarization between the filler and rubber matrix. In conclusion, the innovative filled-MBi elastomer composite would pave the way for an eco-friendly product that is valid for various applications. • Using alternatives to carbon black to achieve sustainability and a clean environment. • Agricultural waste was converted into highly surface-activity biochar. • Surface modification of biochar using stearic acid to enhance its dispersion in NBR composite. • Converting waste into useful and sustainable products to achieve a win-win strategy. • Opened a new path by using biochar in rubber instead of the carbon black. [ABSTRACT FROM AUTHOR]

• The motor behavior of droplet on tilted superhydrophobic dust surface was observed. • A dynamic model of droplet rolling dust removal was established. • The droplet cleaning effect can be controlled by the drop height and tilt angle. This study proposes a method for adjusting the mass of droplet dust removal based on droplet height and photovoltaic tilt angle, utilizing a model of droplet motion on inclined superhydrophobic surfaces. A droplet's motion on dusty and inclined hydrophobic surfaces is analyzed using a high-speed digital imaging system. The impact of drop height and photovoltaic tilt angle on the mass of dust removed by the droplet is experimentally investigated. The findings reveal that the mass of droplet dust removal increases quickly with the rise of drop height and tilt angle. The modification of the tilt angle yields a more pronounced enhancement in dust removal efficiency. At an angle of 40°, the drop height rises from 0.5 cm to 10 cm, leading to an extra 6.6 mg of dust removal per drop. At a height of 0 cm, the mass increased by 10.62 mg after raising the angle from 10° to 40°. Droplet impact on the surface is prone to shattering. The emitted minute droplets will adhere to the surface and form a cohesive ash band, with a visible light transmission rate of merely 67 %. When a droplet rolls on a tilted superhydrophobic surface, there's a dust removal threshold. Once exceeded, the rolling shape tends to become ellipsoidal. The experimental and model predictions of droplet dust removal mass are of the same order of magnitude and differ by a few micrograms. Therefore, the theoretical model can be used to improve the efficiency of droplet dust removal by adjusting the drop height and photovoltaic angle. [ABSTRACT FROM AUTHOR]

• High-speed photography used to study micro-droplet ejection on super-hydrophobic surfaces. • Impact velocity is crucial for controlling micro-droplet ejection. • Initiated chemical vapor deposition method was used to change surface wettability. • Jet is caused by the blast of air-cavity collapse, verified by visualization experiment. • Ejection occurs at velocities of 0.26–1.31 m/s, classified into 5 stages. Impact velocity plays a crucial role in the control of droplet ejection when producing micro-droplets with directed diameters and velocities from millimetre-sized droplets. In this study, high-speed photography is used to experimentally investigate the characteristics of the ejection of micro-droplets after impacting a super-hydrophobic surface with different impact velocities ranging from 0.16 to 2.34 m/s. The results indicate that droplet ejection only occurs at impact velocities ranging from 0.26 to 1.31 m/s. Furthermore, it is found that the droplet ejection process can be classified into five stages based on the Weber number. In Stages 1–3, the ratio of the ejected to initial droplet diameters changes only slightly with the Weber number. In Stage 4, the ratio first increases, then decreases, and finally increases again. In Stage 5, the ratio decreases linearly. An equation describing the decrease in the ratio during Stage 5 is obtained and the correlation between the ratio of the ejection to impact velocities and the Weber number for the same stage is investigated. It is concluded that the formation of the central liquid column and the final characteristics of droplet ejection are mainly the result of the competition among inertial force, reaction force from the surface, gravity, and surface tension; and the formation of the jet is determined by the collapse of the air cavity. [ABSTRACT FROM AUTHOR]

• A super-hydrophobic, electromagnetic shielding titanium nitride film is prepared. • Increasing the sputtering power can construct a low energy, high roughness surface. • Increasing the sputtering power will improve the electromagnetic shielding effectiveness. • Film with 151.3 °contact angle and 40 dB shielding effectiveness is obtained. A super-hydrophobic, electromagnetic shielding titanium nitride (TiN) film was prepared using reactive magnetron sputtering by adjusting the sputtering power (30, 90, 180 and 250 W). The results showed that preferred orientation of the film had an obvious change with increasing sputtering power. At 30 W, too low sputtering power was not conducive to the crystallization of the film. At 90 W, TiN film grew toward [200] preferred orientation with a flat and compact surface, while the preferred orientation was [111] at 180 and 250 W with an uneven surface. Higher sputtering power could construct a low energy and high roughness surface which was helpful to improve the hydrophobic property. The water contact angle of the as-prepared TiN film at 250 W was 151.3°, indicating the achievement of super-hydrophobic property. Due to the decrease of electrical resistivity, the increase of film thickness and the special microstructure of pyramidal nanoparticles, the electromagnetic shielding effectiveness of TiN film at sputtering power of 250 W was about 40 dB, meaning that TiN film had good expect to be a super-hydrophobic, electromagnetic shielding material in the industrial field. [ABSTRACT FROM AUTHOR]

Super-hydrophobic surface has been widely studied, related to surface self-cleaning and liquid transport. In this study, effects of the inclined angle and impact velocity on the dynamic characteristics of droplet impact are experimentally investigated, using high-speed photography. When the spreading break-up does not occur, the effect of the inclined angle on the maximum spreading diameter is mainly determined by the competition between the decrease in the inertial force component normal to the surface and the increase in the gravity and inertial force component parallel to the surface. A formula has been developed to predict the maximum spreading factor under different inclined angles. The increasing inclined angle promotes the complete rebound. When the impact velocity is constant, there exists a critical inclined angle, at which the rebounding time is minimum. Furthermore, the critical inclined angle increases with the impact velocity. The increasing inclined angle can affect droplet ejection and potentially hinder its occurrence. Droplet ejection is classified into five stages based on the change in the ratio of the ejected to initial droplet diameter versus Weber number normal to the surface. For stage 5, an empirical formula that predicts the diameter of ejected droplets under different inclined angles is given out. This study can provide a novel idea for the generation and transport of microdroplets of directed size, as well as the recycling of the remaining liquid film after droplet ejection. [Display omitted] [ABSTRACT FROM AUTHOR]

Super-hydrophobic film with hierarchical micro/nano structures was prepared by galvanic replacement reaction process on the surface of galvanized steel. The effects of the etching time and copper nitrate concentration on the wetting property of the as-prepared surfaces were studied. Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and electrochemical technique were employed to characterize the surface morphology, chemical composition, and corrosion resistance. The stability and self-cleaning property of the as-fabricated super-hydrophobic film were also evaluated. The super-hydrophobic film can be obtained within 3 min and possesses a water contact angle of 164.3° ± 2°. Potentiodynamic polarization measurements indicated that the super-hydrophobic film greatly improved the corrosion resistance of the galvanized steel in 3.5 wt % NaCl aqueous solution. The highest inhibition efficiency was estimated to be 96.6%. The obtained super-hydrophobic film showed good stability and self-cleaning property. [ABSTRACT FROM AUTHOR]

Super-hydrophobic surfaces have attracted a lot of interest in basic research and application. In this paper, periodic micro-structures of micro-scale papillary-like pits with a different center distance were fabricated on Mg-3Al-1Zn (AZ31) magnesium surface via laser ablation. After being chemical etched by AgNO 3 and surface modified with stearic acid, the as-prepared surfaces showed super-hydrophobic properties and the maximum contact angles reached 158.2°. Besides, a conversion from low adhesion to high adhesion was achieved by adjusting the micro-structure of magnesium alloy. The corrosion resistance of super-hydrophobic surfaces in Cassie state (low adhesion) is better than that in Wenzel state (high adhesion). Compared with bare substrates, the corrosion resistance of as-prepared surfaces was improved significantly according to electrochemical measurements. Moreover, the super-hydrophobic surfaces exhibited excellent chemical and thermal stability at a large range of pH solutions and temperatures. This method can be extended to other engineering materials easily and especially would be used in liquid corrosion and changeable corrosion rate according to requirement in industrial field. [ABSTRACT FROM AUTHOR]

In marine and industrial environments, salts and aggressive contaminants in water may cause corrosion and degradation, including acid corrosion and erosion. Super‐hydrophobic (SH) metal oxide films can keep surfaces dry by expelling water droplets. This inhibits corrosion. However, acid rain can dissolve the metal oxide films. Thus, it is necessary to protect SH films against acid erosion. In this work, a WO3 film was added on top of CuO‐coated SH copper surface using electrochemical deposition. The composite SH CuO‐WO3 film exhibited a strong acid resistance. After 48 h immersion in 0.2 N sulfuric acid, the film retained its nearly perfect micro‐nano structure with a static water contact angle of 160 ± 2°. After acid erosion, the corrosion rate in a 3.5% (w/w) NaCl solution was tested using potentiodynamic polarization curves. Its corrosion current density was found to be four orders of magnitude lower compared with CuO‐coated copper. This kind of acid resistant SH surfaces with much enhanced ability against atmospheric oxygen corrosion in the presence of salty water have potential applications in marine and other industrial environments. [ABSTRACT FROM AUTHOR]

The energy performance of nanothermites in aqueous conditions is commonly restricted by the rapid heat dissipation and corrosion of nano-Al. Here we report studies on the fabrication and submerged ignition for the super-hydrophobic nanothermite film based upon the Co 3 O 4 /Al core/shell nanowires (NWs). The Co 3 O 4 NWs arrays, which are synthesized using a facile hydrothermal-annealing method, serve as templates for the deposition of Al shells by magnetron sputtering. The super-hydrophobic surface is subsequently realized by the fluoroalkylsilane coating. The tests of the laser-induced underwater ignition reveal that the super-hydrophobic modification effectively could lead to the ignition of the nanothermite film. Furthermore, the anti-aging behaviors of the obtained super-hydrophobic nanothermite film in aqueous conditions are investigated in detail to compare the heat-release and ignition characteristics at different submersion times. Impressively, the resultant super-hydrophobic composite could still hold about 50% of the original energy even after an underwater storage of 2 days. [ABSTRACT FROM AUTHOR]

A super-hydrophobic (SH) CuO surface was prepared on copper using chemical etching followed by fluorination treatment. The relationship between surface morphology and hydrophobicity was investigated. When the etching time varied from 5 to 120 min, morphology changed from sparse sharp needles to dense sharp needles, and then to a stamen-like structure with flower-like clusters. All these surfaces were SH with the dense micro-needle surface (10 min etching) the best. This SH surface made salt (NaCl) particles deliquesce and roll away. Electrochemical tests showed that it reduced corrosion in a 3.5% (w/w) NaCl solution by more than 10 2 times. [ABSTRACT FROM AUTHOR]

• Super-hydrophobic substrate was constructed for methane hydrate growth. • Fluctuation at gas/liquid interface domains the substrate hydrate growth. • Fluctuation structures at gas/liquid interface was revealed via in-situ Raman. As one of the most efficient promoters for methane hydrate formation, SDS (sodium dodecyl sulfate) works mainly by causing the hydrates to grow upwards along the reactor sidewall. In this work, super-hydrophobic surface was constructed and adopted for methane hydrate formation, in the aim of revealing the promotion mechanism of SDS. Morphological observations showed that SDS led to violent fluctuation at the gas/liquid interface, which represented the unstable state of the gas/liquid interface during the initial hydrate growth process and reached stable via morphology transformation, either upward growth or outward diffusion, leading to the surface growth of methane hydrates. In-situ Raman Spectra revealed that the fluctuation structure was the combination of water, hydrate mass with cages minorly occupied by methane molecules, and methane hydrates; and with the continuation of the fluctuation phenomenon, the water percentage decreased, the hydrate mass increased and then transformed to methane hydrates gradually. [ABSTRACT FROM AUTHOR]

A new kind of self-powered sensor which can synchronously detect the salinity of water solution from 0 mmol/L to 1 mmol/L and generate electricity is developed. The power generation of this self-powered sensor is realized by repeatedly moving water droplets down from hydrophobic PDMS surface to generate negative charges on the surface of PDMS at first and change the capacitance between two electrodes to drive the screen charges (electrons) moving back and forth between two electrodes, subsequently. The ability for droplet to change the capacitance depends on its salinity. So the self-powered sensor can successfully detect the solution's salinity. Furthermore, both the distance between two electrodes and the thickness of PDMS film can influence the change quantity of capacitance when the water droplets are same, which benefits to the improvement of self-powered sensor's detection ability. Finally, the performance of this self-powered sensor can also be optimized by improving its current signal through modulating external load. [ABSTRACT FROM AUTHOR]

Corrosion failure is a thorny issue that restricts the applications of Al alloys. As a research hotspot in functional realization, hydrophobic fabrication exactly offers an efficient method to settle metallic corrosions. This work has developed a facile and low-cost method to enhance corrosion resistance of Al alloys. The micro-nano dendrites have been firstly prepared on metallic substrate using one-step potentiostatic deposition. Then, wetting and electrochemical behaviors have been systematically investigated after stearic acid modification. Results show that the as-prepared surface possesses amplified and durable water repellence with an apparent contact angle (CA) of 154.2° and a sliding angle (SA) of 4.7°. Meanwhile, owing to the trapped air in dendrites, the newly-generated solid-air-liquid interfaces help to resist seawater penetration by reducing interfacial interactions on the super-hydrophobic surface as well as significantly enhance its corrosion resistance. This work sheds positive insights into extending the applications of Al alloys in many areas, especially for ocean engineering fields.

We report a simple and inexpensive method for producing super-hydrophobic surfaces through direct replication of micro/nano-structures on polydimethylsiloxane (PDMS) from a replication master prepared by ultrafast-laser texturing process. Gratings were obtained on 304L stainless steel plate using picosecond laser ablation. It has been used as a master with grating areas of different structural features. PDMS negative replica was prepared from the masters, and PDMS positive replica was prepared from the negative replica thereafter. Wettability of samples of the steel master, negative and positive replicas was distinguished using the apparent contact angle (CA) of water drop. Relationships between the CAs on three kinds of samples and structural features were presented. Super-hydrophobic behavior with self-cleaning, exhibited by a water contact angle of 164.5° and sliding angle of 8.44°, was observed on the PDMS negative replica surface. The negative and positive replicas were sputtered on gold films, which were used to metalized PDMS and eliminate the submicron/nano-structures in hierarchical structures. Results prove that submicro/nano-structures of hierarchical structures enhance the hydrophobicity of material surface remarkably. This replication method can be applied for large scale production of micro/nano textured super-hydrophobic surfaces for commercial applications. [ABSTRACT FROM AUTHOR]

In this work, we show the influence of the liquid electrolyte adsorption by porous films made of poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate), PEDOT:PSS, on the operation of an Organic Electro-Chemical Transistor with an active channel based on these polymeric films. In particular, the effect of film hydration on device performance is evaluated by studying its electrical response as a function of the spatial position between the electrolyte and the channel electrodes. This is done by depositing a PEDOT:PSS film on a super-hydrophobic surface aimed at controlling the electrolyte confinement next to the electrodes. The device response shows that the confinement of ionic liquids near to the drain electrode results in a worsening of the current modulation. This result has been interpreted in the light of studies dealing with the transport of ions in semiconducting polymers, indicating that the electrolyte adsorption by the polymeric film implies the formation of liquid pathways inside its bulk. These pathways, in particular, affect the device response because they are able to assist the drift of ionic species in the electrolyte towards the drain electrode. The effect of electrolyte adsorption on the device operation is confirmed by means of moving-front measurements, and is related to the reproducibility of the device operation curves by measuring repeatedly its electrical response. [ABSTRACT FROM AUTHOR]

Highlights: [•] Superhydrophobic surfaces were fabricated via ion (Ag+, Cu2+) assisted chemical etching method on Zn substrate within 5s followed by coating FAS. [•] Rough Zn surfaces consist of micro/nanometer-scale composite structure formed by corrosion and metal deposition. [Copyright &y& Elsevier]

Wind turbines are often built in areas prone to icing in winter, such as high altitudes and humidity. When wind turbine blades rotate, they collide and capture super-cooled water droplets to form ice, which causes significant hidden dangers to the safe operation of wind turbines. The super-hydrophobic surface is an attractive topic in the field of anti-icing research. However, the low weather resistance of the existing super-hydrophobic surface limits its large-scale application. This paper proposes a one-step preparation method for a robust super-hydrophobic surface. Its hydrophobicity, wear resistance, and other properties are tested. We have experimented with super-hydrophobic blades and control blades in a natural icing environment. The results show that the prepared super-hydrophobic blade has better wear resistance, acid, and alkali resistance. The super-hydrophobic surface has a retardation effect on glaze and mixed ice only in the initial icing stage. The robust super-hydrophobicity limits the frozen area. Throughout the icing period, the effectiveness of super-hydrophobic surfaces is limited. Although the prepared surface effectively improves the robustness, the super-hydrophobic surface is still very challenging in anti-icing applications. • Design a one-step preparation method for robust super-hydrophobic surface • Conduct anti-icing experiments in the natural environment • The super-hydrophobic surface can reduce the weight and thickness of icing on wind turbine blades • The anti-icing function of the super-hydrophobic surface only takes effect in the initial stage of icing [ABSTRACT FROM AUTHOR]

Abstract: Exosomes are very small vesicles that are shed from a variety of cell types. They are present in body fluids comprising blood, urine and ascites, and they hold the potential to serve as indicators in the diagnosis, prognosis and surveillance of a variety of health conditions. In consideration of this, there is broad interest worldwide in deriving and understanding their biochemical composition. Here, small drops of solutions containing exosomes, isolated from either healthy (CCD841-CoN) or tumor (HCT116) colon cells, were manipulated using super-hydrophobic surfaces (SHSs) decorated with nano-geometry based photonics structures. SHSs are surfaces with superior properties, including a reduced friction coefficient, on account of which they can be used to control diluted solutions of biological or medical interest. The combination of this technology with optical resonance phenomena, open up terrific opportunities in the detection, analysis or characterization of biological compounds. Therefore, exosomes were conveniently concentrated and conveyed onto the Surface Enhanced Raman Spectroscopy (SERS) active areas of the substrate, whereby they were analyzed and characterized with extreme precision. Results indicate a difference in the concentration of some biological compounds, and namely: exosomes derived from healthy cells exhibit higher intensities of the peaks corresponding to lipids vibrations, while exosomes extracted from tumor cell lines exhibit a richer RNA content. [Copyright &y& Elsevier]

Super-hydrophobic Polypropylene surfaces were prepared employing combination method of replicating an artificial template and subsequent lifting off the masterviaa splitting way. The super-hydrophobic polypropylene surface, which was prepared using a 500-mesh PTFE-coated sieve, has gradient structures that microbumps with typical height and radius of approximately 20 µm and nano bundles on top of the bump surface. This surface exhibits the same self-cleaning property as the lotus leaf with water contact angle of 152.2 ± 2° and sliding angle less than 5°. The whole preparation process is simple, efficient, large-scale-prepare and environmentally friendly without organic solvents pollution. [ABSTRACT FROM AUTHOR]

Abstract: Porous super-hydrophobic polyvinyl chloride (PVC) surfaces were obtained via a facile solvent/non-solvent coating process without introducing compounds with low surface energy. The microstructure, wetting behavior, and corrosion resistance of resultant super-hydrophobic PVC coatings were investigated in relation to the effects of dosage of glacial acetic acid and the temperature of drying the mixed PVC solution spread over glass slide substrate. As-prepared PVC coatings had porous microstructure, and the one obtained at a glacial acetic acid to tetrahydrofuran volume ratio of 2.5:10.0 and under a drying temperature of 17°C had a water contact angle of 150±1.5°, showing super-hydrophobicity. In the meantime, it possessed very small contact angles for liquid paraffin and diiodomethane and good corrosion resistance against acid and alkali corrosive mediums, showing promising applications in self-cleaning, waterproof for outer wall of building, seawater resistant coating, and efficient separation of oil and water. [Copyright &y& Elsevier]

A novel approach was proposed to fabricate super-hydrophobic surfaces by depositing aggregates of fumed silica modified with hydroxy-terminated poly-dimethylsioxane and γ-aminopropyltriethoxysilane on surfaces of glass plates. The glass plates were treated with 2,3-epoxy propoxy propyltrimethoxysilicane based on an epoxy-amine system in advance. Aggregates of fumed silica were found to be chemically bonded to the treated glass surfaces and a surface possessing dual micron- and nanoscale hierarchical structures was observed on the super-hydrophobic surfaces. The laboratory testing results showed that the obtained surfaces possessed long-term super-hydrophobicity in air and maintained its super-hydrophobicity over a wide pH range. [ABSTRACT FROM AUTHOR]

Abstract: A flower-like super-hydrophobic surface on the copper foil was fabricated by means of a facile method using solution immersing. The water contact angle of this surface was measured to be as high as 156.2° after modified with fluoroalkylsilane (FAS) coating. To study its effect on frost deposition, a series of micro-observations of the water droplets formation, initial frost crystals growth and frost layer melting process were carried out on both the super-hydrophobic surface and the plain copper foil surface. The experimental results show that the water droplets condensed on the super-hydrophobic were smaller and present a more spherical shape when compared with that on the plain copper foil surface. The freezing time of the droplets on the super-hydrophobic surface was later than that on the plain copper foil surface. Moreover, the super-hydrophobic surface can restrain initial frost crystals formation for 20min after exposed to the air for one month. The mechanism of surface hydrophobicity influence on droplets frozen and frost formation was analyzed theoretically based on the surface wettability and the phase transition theory. [ABSTRACT FROM AUTHOR]

Pulsed UV laser ablation is applied to fabricate super-hydrophobic surfaces on metal substrates. The spike shape micro-structure arrays achieved by the laser ablation on the brass substrates increase the surface roughness (Ra) from ∼ 400 nm to ∼ 5 μm. Meanwhile, plenty of nano-structures (200 ∼ 600 nm) are also formed and scattered on the surface of the micro-structures. It is found that the water contact angle of the brass substrate increases from 110° to 161°. Super-hydrophobic property of the metal surfaces with both the micro- & nano-roughness is explained by water repellent model for double roughness structures. High speed camera imaging is used to analyze water droplet dynamics during its rolling down along the slanted super-hydrophobic brass surface. It shows that the pulsed laser ablation is a versatile approach to create large area super-hydrophobic surfaces for industrial applications. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical impedance spectroscopy, potentiodynamic polarization and scanning electron microscopy were carried out to determine the effect of super-hydrophobic surfaces on the marine bacterium Vibrio natriegens (V. natriegens) adhesion. Four different samples were prepared in order to investigate the anti-biocorrosion mechanism of super-hydrophobic surfaces. Potentiodynamic polarization suggested that the V. natriegens attached on the surface mainly enhanced the reaction kinetics of the anodic reaction and accelerated the dissolution of aluminum. EIS results were interpreted with different equivalent circuits to model the physicoelectric characteristics of the electrode/biofilm/solution interface. The results showed that neither anodization nor chemical modification could decrease the bacterial adhesion and corrosion rate individually. V. natriegens showed only weak attachment to the super-hydrophobic surface, and the biocorrosion mechanism was closely associated with surface energy and surface topography. [Copyright &y& Elsevier]

To design a surface with large slip or larger drag reduction is a pop issue in the fields of liquid transporting and body swimming. In this context, it is a crucial problem to measure the slip length for these surfaces. Here we propose a novel method by using rheometer for this objective. This method is implemented by designing the distribution of the super-hydrophobic area on the sample. Using this method, a slip length of 40 μm for 70 wt% glycerin flow over a super-hydrophobic surface with stripe structure (the period, width and height of ridges are 150 μm, 40 μm and 65 μm, respectively) is measured. The result shows that the slip length measured using this method is in good agreement with former results measured by other methods. This method is fit for measuring the slip length of super-hydrophobic surface whose structure ranges from micro- to nano- scale. [ABSTRACT FROM AUTHOR]