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

Durable, multifunctional cotton fabrics with in situ deposited micro/nanomaterials for effective self-cleaning, oil-water separation and antibacterial activity

The facile modification of cotton fabrics for excellent self-cleaning, oil-water separation, and antibacterial activity is of great interest for multifunctional requirements. Herein, a durable, robust, fluorine-free multifunctional cotton fabric was fabricated via in-situ growing zeolitic imidazolate framework-67 (ZIF-67) on the cotton surface, followed by depositing hydrophobic SiO2 (H-SiO2) nanoparticles synthesized via an improved Stöber reaction. Meanwhile, the abundant hydroxyls of the cotton fabrics provided the necessary ion interaction sites for the uniform deposition of micro/nanomaterials, confirmed by the visualized Raman imaging technology. The resultant H-SiO2/ZIF-67@cotton fabric exhibited superhydrophobicity with a water contact angle of 159° and versatile self-cleaning, antifouling, oil-water separation, as well as prominent antibacterial activity against S. aureus and E. coli. At the same time, the superhydrophobic cotton fabric possessed excellent durability and stability against harsh environments, including abrasion, washing, acid, base, salt, and organic solvents. This facile technique can be applied for large-scale production of multifunctional superhydrophobic cotton fabrics due to its easy operation, low cost, and environmental friendliness.

Robust superhydrophobic cotton fabric based on dual-sized silica particles with self-healing nature

Improving the durability of wear-resistant superhydrophobic surfaces is crucial for their practical use. To tackle this, research is now delving into self-healing superhydrophobic surfaces. In our study, we developed superhydrophobic cotton fabrics by embedding nano-silica particles, micro-silica powder, and polydimethylsiloxane (PDMS) using a dipping method. This innovative design grants the SiO2/PDMS cotton fabric remarkable superhydrophobicity, reflected by a water contact angle of 155°. Moreover, the PDMS was stored in the amorphous areas of cellulose of cotton fabrics, attaching to the fiber surface and playing a role in connecting micro-blocks and nano-particles. This causes a self-diffusion of PDMS molecules in these fabrics, allowing the surface to regain its superhydrophobicity even after abrasion damage. Impressively, this self-healing property can be renewed at least 8 times, showcasing the fabric's resilience. Moreover, these superhydrophobic cotton fabrics exhibit outstanding self-cleaning abilities and repel various substances such as blood, milk, cola, and tea. This resilience, coupled with its simplicity, low cost-effectiveness, and eco-friendliness, makes this coating highly promising for applications across construction, chemical, and medical fields. Our study also delves into understanding the self-healing mechanism of the SiO2/PDMS cotton fabric, offering insights into their long-term performance and potential advancements in this field.

Novel Superhydrophobic Copper Mesh-Based Centrifugal Device for Edible Oil-Water Separation

Edible oil is essential for people's daily life but also results in a large amount of oily wastewater simultaneously. Oil-water separation is a practical route that can not only purify wastewater but also recycle valuable edible oil. In this study, the superhydrophobic copper mesh (SCM) was prepared by chemical etching, and a novel oil-water centrifugal device was designed for high-efficiency separation of edible oil wastewater. The kernel is a self-prepared SCM, which has a water contact angle (WCA) of 155.1 ± 1.8° and an oil contact angle (OCA) of 0°. Besides, the separation performance of the SCM for edible oil-water mixtures was studied in this study. The results showed that the SCM exhibited excellent oil/water separation performance, with a separation efficiency of up to 96.7% for sunflower seed oil-water wastewater, 93.3% for corn oil-water wastewater, and 98.3% for peanut oil-water wastewater, respectively. Moreover, the separation efficiency was still over 90% after 18 cycles. A model was established to analyze the oil-water separation mechanism via centrifugation. The oil-water centrifugal separation device has great potential for scale-up applications.

Successful Fabrication of Hydrophobic Surfaces of Microstructures Cooperating with Solid-Liquid Nanomaterials on the CuZnPb Alloy Substrate

For protecting the exquisite structural patterns of such coins, developments of simple preparation methods were explored to achieve good hydrophobic capability and the wear-damage resistance of CuZnPb surfaces. A self-cleaning nanoliquid (SN) was combined with microstructured Ag-dispersed CuZnPb (MAC) to realize good hydrophobicity functions of the SNMAC. This was because the cooperative functions of silver and the SN enhanced the water reunion ability and increased solid-liquid-gas contact areas, leading to high contact angles of SNMAC. Their cooperations produced discrepant forces in their respective areas of the water drops and increased heterogeneous flowing, resulting in a high-angle hysteresis of SNMAC. Subsequently, the wear-damage resistance of the hydrophobic interface was measured in a ball-on-flat tribopair system, and the results showed that sliding injuries made a height distribution of the hydrophobic surface trend toward an equalization, allowing the cooperation of nano-silver, SN, and CuZnPb to form a new-style interface for achieving excellent hydrophobicity, thus producing the highest contact angles of the SNMAC among the as-prepared samples.

Chemical Etching, Thermally Driven Combination Strategy to Fabricate Superhydrophobic Fe-Based Amorphous Coatings with Excellent Anticorrosion Property: Based on Hydroxylation Effect

Fe-based amorphous coatings are ideal materials for surface protection due to their outstanding mechanical properties and corrosion resistance. However, coating defects are inevitably formed during the preparation of coatings by thermal spray technology, which seriously affects the corrosion performance. Inspired by bionics, conceiving superhydrophobic surfaces with liquid barrier properties has become a new idea for the corrosion protection of metal surfaces. In this work, based on surface hydroxylation, we designed a superhydrophobic Fe-based amorphous coating with corrosion resistance by chemical etching combined with a thermally driven preparation strategy. The obtained superhydrophobic coatings exhibit liquid repellency (contact angle >150°) and excellent corrosion resistance (corrosion current density and passive current density reduced by 3 orders of magnitude). The results revealed that the superhydrophobic behavior stems from the construction of hydroxyl-induced surface micro-/nanomultilevel aggregates (cluster structures). The hydrophobic agent layer deposited on the surface of cluster aggregates and the nanoparticle elements that constitute the clusters dominate the corrosion resistance of the coating. This work provides an effective guide to the design of high-corrosion-resistant Fe-based amorphous alloy coatings and promotes their engineering applications.

A review of self-cleaning coatings for solar photovoltaic systems: theory, materials, preparation, and applications

Photovoltaic power generation is developing rapidly with the approval of The Paris Agreement in 2015. However, there are many dust deposition problems that occur in desert and plateau areas. Traditional cleaning methods such as manual cleaning and mechanical cleaning are unstable and produce a large economic burden. Therefore, self-cleaning coatings, which have unique mechanisms and high adaptability, have attracted wide attention in the photovoltaic industry and scientific community, especially the super-hydrophobic and super-hydrophilic coatings. The paper systematically reviewed the theory, materials, preparation, and applications of the super-hydrophobic and super-hydrophilic coatings on the photovoltaic modules. Super-hydrophobic materials such as organosilicon compounds, fluorinated polymers, and some inorganic materials are popular. TiO2 is widely used to prepare super-hydrophilic coatings on glass covers of photovoltaic panels due to its good photocatalytic activity. CVD-based surface treatment is suitable for preparing photovoltaic self-cleaning surfaces. These methods prepare self-cleaning surfaces by reacting gaseous substances with hot surfaces and depositing them on the surface. They are efficient but difficult to control accuracy. When applied to photovoltaic modules, it is crucial to consider the factors such as self-cleaning, transparency, anti-reflection, anti-icing, and durability. In future research, it is significant to improve the transparency, durability, and self-cleaning properties of coatings.

Preparation and corrosion resistance of superhydrophobic Ni-Co-Al2O3 coating on X100 steel

X100 steel is easy to be corroded because of the high salt content in alkaline soils. The Ni-Co coating can slow down the corrosion but still cannot meet the requirements of modern demands. Based on this, in this study, on the basis of adding Al₂O₃ particles to the Ni-Co coating to strengthen its corrosion resistance, combined with superhydrophobic technology to inhibit corrosion, a micro/nano layered Ni-Co-Al₂O₃ coating with a new combination of cells and papillae was electrodeposited on X100 pipeline steel, and superhydrophobicity was integrated into it using a low surface energy modification method to improve wettability and corrosion resistance. SEM, XRD, XPS, FTIR spectroscopy, contact angle, and an electrochemical workstation were used to investigate the superhydrophobic materials' microscopic morphology, structure, chemical composition, wettability, and corrosion resistance. The co-deposition behavior of nano Al₂O₃ particles can be described by two adsorption steps. When 15 g L^-1 nano Al₂O₃ particles were added, the coating surface became homogeneous, with an increase in papilla-like protrusions and obvious grain refinement. It had a surface roughness of 114 nm, a CA of 157.9° ± 0.6°, and -CH₂ and -COOH on its surface. The corrosion inhibition efficiency of the Ni-Co-Al₂O₃ coating reached 98.57% in a simulated alkaline soil solution, and the corrosion resistance was significantly improved. Furthermore, the coating had extremely low surface adhesion, great self-cleaning ability, and outstanding wear resistance, which was expected to expand its application in the field of metal anticorrosion.

Flower-like Superhydrophobic Surfaces Fabricated on Stainless Steel as a Barrier against Corrosion in Simulated Acid Rain

Functionalisation of the metal surface of low-carbon ferritic stainless steel (from hydrophilic to hydrophobic properties) was achieved by flower-like hierarchical structures on a steel substrate prepared by a low-cost immersion method. The flower-like structured hydrophobic layers on the steel substrate were obtained by immersing the samples in an ethanolic solution of stearic acid with the addition of various concentrations of expired vitamin E ((+)α-tocopherol). The stability and corrosion-inhibiting effect of the hierarchically structured (such as natural cornflower) hydrophobic layers were studied systematically during short and long immersion tests, 120 h (five days) in an acidic environment (pH = 3) using potentiodynamic measurements, electrochemical impedance spectroscopy and chronopotentiometry. The surfaces of the samples, their wettability, surface morphology and chemical composition were characterised by contact angle measurements, SEM, ATR-FTIR and EDAX. After 120 h of immersion, the inhibition efficiency of the flower-like structured hydrophobic layers on the steel substrate in the selected corrosion medium remained above 99%, and the hierarchical structure (flower-like structure) was also retained on the surface.

Biomimetic superhydrophobic metal/nonmetal surface manufactured by etching methods: A mini review

As an emerging fringe science, bionics integrates the understanding of nature, imitation of nature, and surpassing nature in one aspect, and it organically combines the synergistic complementarity of function and structure–function integrated materials which is of great scientific interest. By imitating the microstructure of a natural biological surface, the bionic superhydrophobic surface prepared by human beings has the properties of self-cleaning, anti-icing, water collection, anti-corrosion and oil–water separation, and the preparation research methods are increasing. The preparation methods of superhydrophobic surface include vapor deposition, etching modification, sol–gel, template, electrostatic spinning, and electrostatic spraying, which can be applied to fields such as medical care, military industry, ship industry, and textile. The etching modification method can directly modify the substrate, so there is no need to worry about the adhesion between the coating and the substrate. The most obvious advantage of this method is that the obtained superhydrophobic surface is integrated with the substrate and has good stability and corrosion resistance. In this article, the different preparation methods of bionic superhydrophobic materials were summarized, especially the etching modification methods, we discussed the detailed classification, advantages, and disadvantages of these methods, and the future development direction of the field was prospected.

Constructing Superhydrophobic Surface on Copper Substrate with Dealloying-Forming and Solution-Immersion Method

In this study, a superhydrophobic surface was constructed on a copper substrate through dealloying-forming and solution-immersion methods. The dealloying process for nanostructures on a copper surface involved the electrodeposition of zinc atoms, and the thermal alloying and chemical dealloying of zinc atoms. Then, a dealloyed copper surface was subsequently modified with low-surface-energy copper stearate to produce a superhydrophobic surface. Scanning electron microscopy, X-ray diffractometry, and Fourier transform infrared spectrometry were employed to characterize the morphological features and composition components of the surface in the fabrication process. The static contact angles of the copper surfaces were compared and evaluated based on various fabrication parameters, including electric current density, corrosive solution concentration, and nanostructures. The results indicated that a leaf-like copper stearate could be constructed through immersing a dealloyed copper plate into a 0.005 mol/L ethanol solution of stearic acid for 5 min. Nanostructures provided more attachment areas on the copper surface to facilitate the formation of copper stearate. The resulting as-prepared surface presented excellent superhydrophobic properties with a contact angle of over 156.5°, and showed the potential properties of non-sticking, self-cleaning, anti-corrosion, and stability. This study provides an efficient approach to fabricate superhydrophobic surfaces for engineering copper metals.

Metal organic frameworks (MOFs) as multifunctional nanoplatform for anticorrosion surfaces and coatings

Corrosion of metallic materials is a long-standing problem in many engineering fields. Various organic coatings have been widely applied in anticorrosion of metallic materials over the past decades. However, the protective performance of many organic coatings is limited due to the undesirable local failure of the coatings caused by micro-pores and cracks in the coating matrix. Recently, metal organic frameworks (MOFs)-based surfaces and coatings (MOFBSCs) have exhibited great potential in constructing protective materials on metallic substrates with efficient and durable anticorrosion performance. The tailorable porous structure, flexible composition, numerous active sites, and controllable release properties of MOFs make them an ideal platform for developing various protective functionalities, such as self-healing property, superhydrophobicity, and physical barrier against corrosion media. MOFs-based anticorrosion surfaces and coatings can be divided into two categories: the composite surfaces/coatings using MOFs-based passive/active nanofillers and the surfaces/coatings using MOFs as functional substrate support. In this work, the state-of-the-art fabrication strategies of the MOFBSCs are systematically reviewed. The anticorrosion mechanisms of MOFBSCs and functions of the MOFs in the coating matrix are discussed accordingly. Additionally, we highlight both traditional and emerging electrochemical techniques for probing protective performances and mechanisms of MOFBSCs. The remaining challenging issues and perspectives are also discussed.

Ultrafast and Eco-Friendly Fabrication Process for Robust, Repairable Superhydrophobic Metallic Surfaces with Tunable Water Adhesion

Superhydrophobic metallic surfaces with a water contact angle greater than 150° have attracted considerable attention in both fundamental research and industrial applications due to their special properties such as antibiofouling, drag reduction, self-cleaning, anti-icing, anticorrosion, and oil-water separation. Until now, the development of superhydrophobic practical applications is mainly limited by the process complexity, long fabrication time, coating with toxic materials, and easily damaged surface structure. To reduce the fabrication time, and simplify the process for industrial applications, an eco-friendly postprocess has been developed in this research. The superhydrophobic surfaces on the laser-textured titanium, aluminum, copper, stainless steel, and nickel substrates were fabricated extremely rapidly by a simple surface modification of only a 10 min heat treatment with nontoxic silicone oil. Hydrophobic organic group absorption has been accelerated on the silicone oil heat-treated surface and has created a low-energy surface. In addition, we demonstrated the potential of using the laser areal fluence parameter, which could be an alternative to single-laser process parameters such as scanning speed, power, and step size, to fine-tune the water adhesion behavior. Therefore, a surface that integrates different water adhesion behaviors can be easily fabricated for more complex practical applications such as controlled microdroplet transportation, microfluidic systems, and certain biomedical processes. Moreover, the robustness of superhydrophobic surfaces was confirmed by abrasion tests, knife-scratch tests, chemical durability tests, and aging tests, and their repairability was evaluated for product applications in practice.

Preparation of Iron Ore Tailings-Based Superhydrophobic Coatings

In this study, ball mill pretreated iron ore tailings were modified with tetraethoxysilane (TEOS) and hexadecyltrimethoxysilane (HDTMS) to obtain iron ore tailings/polysiloxane (IOT/POS) superhydrophobic powders, which were subsequently mixed with chloroprene rubber solution (CRS) to prepare durable superhydrophobic composite coatings. The effect of HDTMS amount and reaction time on the wettability of the superhydrophobic powder was investigated. The influence of the superhydrophobic powders concentration on the wettability of the composite coatings as well as the degree of damage of the superhydrophobicity of the composite coating was analyzed by using the sandpaper abrasion and tape peeling tests. Further, SEM and FTIR were used to analyze the formation mechanism of the IOT/POS superhydrophobic powders and coatings. The results showed for an HDTMS amount of 2.5 mmol and reaction time of 4 h, the contact angle of the IOT/POS powder was 157.3 ± 0.6°, whereas the slide angle was determined to be 5.9 ± 0.8°. For an IOT/POS powder content of 0.06 g/mL in CRS, the contact angle value of the superhydrophobic composite coating was 159.2 ± 0.5°, whereas the slide angle value was 5.5 ± 0.8°. The superhydrophobic composite coating still maintained the superhydrophobicity after the sandpaper abrasion and tape peeling tests, which indicated the iron ore tailings solid waste has the potential to prepare superhydrophobic coatings.

Long-Term Static and Dynamic Corrosion Stability of Nonwetting Surfaces

Superhydrophobic surfaces (SHSs) and lubricant-infused surfaces (LISs) are two classes of nonwetting surfaces that have drawn attention due to their advanced functional properties including corrosion inhibition. Yet there is a conspicuous lack of corrosion study of SHSs and LISs with respect to their fabrication and material parameters, especially at high temperatures and under dynamic flow conditions over long durations, which is sought to be addressed in this article. Considering copper SHSs and LISs, a full factorial combinatorial study of two facile texturing processes, electrodeposition and etching, two different functionalization agents, stearic acid and mercaptan, and two types of infused lubricants, Krytox 104 and DOWSIL 510, is presented, encompassing over 650 measurements on 90 tested surfaces. All fabricated surfaces demonstrated water repellency with a contact angle above 150° and a sliding angle below 7°. For the first time, the study examines high-temperature corrosion stability and long-term corrosion durability of the nonwetting surfaces in both static fluid and dynamic turbulent flow conditions over a period of 30 days. LISs and SHSs are shown to provide excellent corrosion inhibition over all tested corrosion conditions, with negligible presence of corrosion species on the surfaces and no deterioration of the texturing. The surfaces are also shown to rejuvenate easily to the initial wettability and corrosion resistance values. This study provides valuable insights into the selection of materials and processing parameters for the fabrication of nonwetting surfaces for the application of interest.

An Anti-Corrosion Superhydrophobic Copper Surface Fabricated by Milling and Chemical Deposition

The development of anticorrosion coatings on copper has raised tremendous interest in material science. Using a milling method, regular rough structures were fabricated, and after chemical deposition with AgNO3 solution and the modification of stearic acid, a superhydrophobic copper substrate could be obtained. The surface morphological study showed a dendritic microstructure, and a rectangular surface bulge produced by milling was distributed on the copper substrate. The coatings showed the surface water contact angle could be as high as 158.4°. The best anti-corrosion coating was the sample milled with the cutter tip distance of 0.30 mm. The as-prepared superhydrophobic sample has a good self-cleaning effect. Scratched with a knife and abraded by friction, the copper substrate still maintained good superhydrophobic nature. The coating was mechanically stable and possessed good corrosion resistance.

Study on Preparation of Superhydrophobic Copper Surface by Milling and Its Protective Performance

Using milling method, a 0.1 mm flat-bottom sharp knife was used to mill the surface of Cu substrate in a CNC engraving machine to construct the microstructure of rectangular bumps, and rectangular bumps with different sizes and different distances were prepared by changing the distance between cutter tips. After deburring and stearic acid modification, a superhydrophobic Cu surface with excellent mechanical durability and stability was successfully prepared. Through friction and wear experiments, the contact angle of the superhydrophobic Cu surface decreased slightly while retaining excellent corrosion resistance.

Study on Frost-Suppression Characteristics of Superhydrophobic Aluminum Surface Heat Exchanger Applied in Air Source Heat Pump

In order to solve the frosting problem of air source heat pump (ASHP) outdoor heat exchange under low-temperature and low-humidity conditions, a superhydrophobic aluminum (Al) surface with a contact angle (CA) of 158.3° was prepared by chemical etching. The microscopic characteristics of droplet condensation and the freezing process of a superhydrophobic surface were revealed through visual experiments and theoretical analysis. On this basis, the frost-suppression effect of a superhydrophobic Al-based surface simulating the distribution of actual heat exchanger fins was preliminarily explored. The results demonstrated that, due to the large nucleation energy barrier and the coalescence-bounce behavior of droplets, the condensed droplets on the superhydrophobic surface appeared late and their quantity was low. The thermal conductivity of the droplets on a superhydrophobic surface was large, so their freezing rate was low. The frosting amount on the superhydrophobic Al-based surface was 69.79% of that of the bare Al-based surface. In turn, the time required for melting the frost layer on the superhydrophobic Al-based surface was 64% of that on the bare Al-based surface. The results of this study lay an experimental and theoretical foundation for the application of superhydrophobic technology on the scale of heat exchangers.

Robust and durable liquid-repellent surfaces

This review provides a comprehensive summary of characterization, design, fabrication, and application of robust and durable liquid-repellent surfaces.

Utilization of Melt Fracture Phenomenon for the Preparation of Shark Skin Structured Hydrophobic Film

With the application of biomimetic shark skin microstructures with hydrophobicity in microfluidics, sensors and self-cleaning materials, microstructure processing methods are increasing. The preparation process has higher requirements for processing cost and efficiency. In this paper, linear low-density polyethylene (LLDPE) hydrophobic films were prepared with the help of melt fracture phenomenon. The equipment is a self-made single screw extruder. By adjusting the process parameters, the biomimetic shark skin structured LLDPE films with good hydrophobic property can be obtained. The surface microstructure shape of the product is related to kinds of additive, die temperature and screw speed. When AC5 was selected as an additive, the optimal processing parameter was found to be 160 °C die temperature and 80 r/min screw speed. A contact angle of 133° was obtained in this situation. In addition, the influences of die temperature and screw speed on the size of shark skin structure were also systematically investigated in this paper. It was found that the microstructure surface with hierarchical roughness had a better hydrophobic property.

Bioinspired nonwetting surfaces for corrosion inhibition over a range of temperature and corrosivity

Applications of superhydrophobic (SHS) and lubricant infused surfaces (LIS) involve exposure to corrosive environments from the acidic to the basic, at a range of temperatures, that are not fully characterized. We present for the first time a multifactorial study of the effects of surface fabrication method, surface modification, surface functionalization time, temperature and pH of the immersion medium on the corrosion performance of nonwetting copper surfaces. Bioinspired SHS and LIS fabricated using facile methods of etching and electrodeposition are systematically assessed using potentiodynamic polarization measurements for their corrosion resistance in saline solution (pH≈ 7) over a temperature range 23-85 °C. SHS and LIS are shown to exhibit diminished corrosion rate, by up to two orders of magnitude, compared to bare copper surface. An Arrhenius model is developed for the first time, describing the temperature-dependent corrosion rate of SHS and LIS. Electrochemical impedance spectroscopy is used to show that corrosion resistance of LIS is larger by three orders of magnitude in extremely acidic (pH = 1) and by an order magnitude in extremely alkaline (pH = 14) media compared to bare copper surface. Etched LIS are generally more resistant to corrosion compared to SHS at all temperatures with excellent microstructural durability.

Superhydrophobic Surface with Stepwise Multilayered Micro- and Nanostructure and an Investigation of Its Corrosion Resistance

We develop a fluorine-free preparation of the superhydrophobic surface on an aluminum alloy with anticorrosion performance and mechanical robustness. The surface morphology, chemical composition, and water repellency were determined with SEM, CLSM, EDS, FT-IR, TG, and contact-angle measurements, respectively. The aluminum matrix superhydrophobic surface (STA-PDMS-ZnO sample) was able to display excellent repellency to water with a WCA of 152° and a WSA of 2°. The outstanding superhydrophobicity on the as-prepared surface was greatly related to the construction of stepwise multilayered micro- and nanostructure within the superhydrophobic surface. Because of the special surface structure, the mechanical robustness and corrosion resistance of the STA-PDMS-ZnO sample were improved. Notably, the anticorrosion mechanism by air pockets was explained by the comparison of two superhydrophobic surfaces prepared with the same low-surface-energy chemicals. The superhydrophobic surface with a multilayered micro- and nanostructure (STA-PDMS-ZnO sample) showed greater corrosion resistance than the surface coated by superhydrophobic modification (control sample). This is because of the entrapments of numerous air pockets within the aluminum matrix superhydrophobic surface, thus strengthening the corrosion resistance. On the basis of the results, the multidimensional superhydrophobic surface is promising for having a good application future in the field of metal corrosion protection.

Superhydrophobic Civil Engineering Materials: A Review from Recent Developments

Superhydrophobic surfaces have drawn attention from scientists and engineers because of their extreme water repellency. More interestingly, these surfaces have also demonstrated an infinite influence on civil engineering materials. In this feature article, the history of wettability theory is described firstly. The approaches to construct hierarchical micro/nanostructures such as chemical vapor deposition (CVD), electrochemical, etching, and flame synthesis methods are introduced. Then, the advantages and limitations of each method are discussed. Furthermore, the recent progress of superhydrophobicity applied on civil engineering materials and its applications are summarized. Finally, the obstacles and prospects of superhydrophobic civil engineering materials are stated and expected. This review should be of interest to scientists and civil engineers who are interested in superhydrophobic surfaces and novel civil engineering materials.

Superhydrophobic Coatings from Recyclable Materials for Protection in a Real Sea Environment

Recyclable materials can be referred to as both those materials directly recycled from wastes and those derived from any kind of transformation before use. Highly water repellent coatings with wettability properties, known as superhydrophobic (SH), are related to surfaces with contact angles above 150° and a very small hysteresis. The small area available for these surfaces when in contact with water can be exploited in many applications in which interactions with an aqueous environment are usually desirable to be avoided, like for protection and friction reduction in a marine environment. SH coatings under investigation have been prepared starting from recyclable materials with the aim to provide a sustainable and low cost solution, with potential application to large surfaces in a marine environment. Wetting studies, surface characterization, and electrochemical tests show how these surfaces can be used in terms of fouling prevention and the protection of metals in underwater conditions.

Robust Superhydrophobic Surface Based on Multiple Hybrid Coatings for Application in Corrosion Protection

A new class of superhydrophobic surface based on multiple hybrid coatings is proposed and prepared to improve mechanical and reproduction stability. It does not only show a large water contact angle (ca. 174.5°) but also a slight decrease (ca. 6.4%) of water contact angle after 100 mechanical abrasion cycles. Furthermore, the water contact angle changes slightly (relative standard deviation, 0.14%) for the three superhydrophobic surfaces prepared with the same procedure. The application of superhydrophobic multiple hybrid coatings in corrosion protection is further investigated by the Tafel polarization curves and electrochemical impedance spectroscopy. The superhydrophobic multiple hybrid coatings showed lower corrosion current (1.4 × 10^-11 A/cm²), lower corrosion rate (ca. 1.6 × 10^-7 mm/year), and larger polarization resistance (7.9 × 10⁴ MΩ cm²) in 3.5 wt % NaCl aqueous solution compared to other superhydrophobic coatings reported in previous works. This work not only confirms the formation of robust superhydrophobic surface for real application in corrosion protection but also provides a new model of superhydrophobic surface based on multiple hybrid coatings with high mechanical, chemical, and reproduction stability for various applications.

A different wettable Janus material with universal floatability for anti-turnover and lossless transportation of crude oil

Flower-like TiO₂ particles were prepared to endow diverse materials with the ability of steady floatability and anti-turnover on different liquids. This strategy was applied in the design of a promising way for lossless transportation of crude oil via sea.

Biomimetic multi-functional superhydrophobic stainless steel and copper meshes for water environment applications

The robust, multi-functional superhydrophobic metal meshes were fabricated by the one-step solution immersion method for water environment applications.