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[Display omitted] In nature, superhydrophobicity is almost systematically associated with a multiscale topography. Nevertheless, multiscale-textured natural surfaces can either produce water-repellent properties such as on the sacred lotus leaf or high liquid-to-solid adhesion such as on the rose petal. To conceive bio-inspired surfaces with self-cleaning properties, the proper contributions of each topographical scale to the wetting behavior need to be investigated. Conditions for the equilibrium of menisci produced at a given topographical scale are derived, yielding a recursion relation between each topographical scale. We introduce the equilibrium anchorage depth to quantify the penetration of water at equilibrium. To study the contact angle hysteresis (CAH), we thoroughly describe the mechanisms driving the advancing and receding motions of the triple line. Both phenomena depend on what we define as precursor advancing and receding motions. Eventually, the equilibrium, advancing and receding anchorage depths are related to the CAH. Topographical heterogeneities at a topographical subscale i are always associated with a reduced equilibrium anchorage depth and an enhanced robustness at all topographical scales of higher orders of magnitude. Eventually, it is demonstrated that advancing and receding anchorage depths are bounded by the equilibrium anchorage depth, elucidating how rose-petal-like surfaces systematically produce a high CAH. [ABSTRACT FROM AUTHOR]

The corrosion problem has significantly impeded the practical application of Mg-Li alloys. In this report, a method that combines micro-arc oxidation (MAO) with electrochemical deposition is developed to create a superhydrophobic matrix on Mg-Li substrate. The combination approach harnesses the superiority of both coverages, including MAO as the dense, firmly bonded ceramic oxide layer on the metal substrate and the superhydrophobic surface (SHS) implanted into MAO matrix. The MAO-SHS coating exhibits high mechanical stability, maintaining the superhydrophobicity due to the "implanting effect" even after a long distance of friction effect. For corrosion inhibition, compared to the bare Mg-Li with i corr of 9.26 × 10−5 A/cm2, the i corr for MAO and MAO-SHS is 7.83 × 10−6 A/cm2 and 7.50 × 10−9 A/cm2, respectively, representing the reduction of approximately one and four orders of magnitude. Focusing the atmospheric corrosion inhibition, MAO-SHS proves to manipulate the dynamic evolution of saline solution evaporation and salt particle deliquation. The salt particle crystalized from saline solution on MAO-SHS is found to have significantly smaller contact area than that of the bare Mg-Li and MAO. By employing atomic force microscopy, the adhesion force of salt particle is revealed as ca. 45 nN, 13 nN, and 2 nN for salt particle on Mg-Li, MAO, and MAO-SHS, respectively. This suggests that the salt can be more easily removed from the MAO-SHS surface, thereby reducing the susceptibility to corrosion. The in situ deliquation is conducted to understand the formation of the droplet on different surfaces. The air in the SHS layer hinders chloride ingress and the SHS layer seals the pores in MAO layer, proving the synergistic effect afforded by MAO-SHS to achieve superior corrosion resistance. [ABSTRACT FROM AUTHOR]

Wearable sensors have attracted considerable interest due to their ability to detect a variety of information generated by human physiological activities through physical and chemical means. The performance of wearable sensors is limited by their stability, and endowing wearable sensors with superhydrophobicity is one of the means to enable them to maintain excellent performance in harsh environments. This review emphasizes the imperative progress in flexible superhydrophobic sensors for wearable devices. Besides, the wettability principle and the mechanism of wearable sensors are briefly introduced to propose the combination of superhydrophobicity and wearable sensors. Next, superhydrophobic substrates for wearable sensors, including but not limited to, polydimethylsiloxane, polyurethane, gel, rubber, and fabric, are described in depth, and also the respective fabrication processes and performances. Moreover, the utility of superhydrophobic wearable sensors in a normal intelligent environment is described, highlighting their application in monitoring physiological signals, such as physical movement, pulse, vibration, temperature, perspiration, respiration, and so on. Finally, this review evaluates the challenges and dilemmas that wearable sensors must be overcome for further development and improve the functional performance of wearable sensors, paving the way for their expansion into advanced wearable sensing systems. [ABSTRACT FROM AUTHOR]

In the last decade, the task of developing environmentally friendly and cost-effective methods for obtaining stable superhydrophobic coatings has become topical. In this study, we examined the effect of the concentrations of filler and polymer binder on the hydrophobic properties and surface roughness of composite coatings made from organic–aqueous compositions based on hexyl methacrylate (HMA) and glycidyl methacrylate (GMA) copolymers. Silicon dioxide nanoparticles were used as a filler. A single-stage "all-in-one" aerosol application method was used to form the coatings without additional intermediate steps for attaching the adhesive layer or texturing the substrate surface, as well as pre-modification of the surface of filler nanoparticles. As the ratio of the mass fraction of polymer binder (Wn) to filler (Wp) increases, the coatings show the lowest roll-off angles among the whole range of samples studied. Coatings with an optimal mass fraction ratio (Wn/Wp = 1.2 ÷ 1.6) of the filler to polymer binder maintained superhydrophobic properties for 24 h in contact with a drop of water in a chamber saturated with water vapor and exhibited roll-off angles of 6.1° ± 1°. [ABSTRACT FROM AUTHOR]

[Display omitted] Coffee rings formed by evaporation of analyte-containing droplets are widely observed in micropatterning, bio-arrays, and trace detection. The coffee-ring effect caused by contact line pinning significantly affects the detection uniformity and sensitivity. Here, we propose a simple and operable method to effectively suppress coffee rings through controllable nanoparticles aggregation by superhydrophobicity-enabled dynamic evaporation. The gold nanoparticles (AuNPs) deposition footprint formed after dynamic evaporation on an integrated superhydrophobic surface was reduced by ∼3 orders of magnitude compared to that of non-interventional evaporation. Detailed experiments, numerical simulations, and theoretical studies have revealed that substrate wettability, temperature and droplet motion behaviors play significant roles in suppressing coffee-ring effect. More critically, based on the force mechanism of AuNPs at the interface/contact line, universal mathematical models and regime maps were established to classify the different deposition modes for AuNPs under different evaporation conditions by introducing dimensionless parameter G, revealing the enrichment mechanism of AuNPs in droplets under superhydrophobicity-enabled dynamic evaporation. The accuracy of the theoretical model and enrichment mechanism was demonstrated through the single-molecule detection of rhodamine 6G with excellent sensitivity (10–17 M, enhancement factor ∼1013) and perfect uniformity (relative standard deviation ∼5.57 %), which provides a valuable guide for research and applications of nanoparticle aggregation. [ABSTRACT FROM AUTHOR]

In this paper, hierarchical micro/nano structures composed of periodic microstructures, laser-induced periodic surface structures (LIPSS), and nanoparticles were fabricated by femtosecond laser processing (LP). A layer of hydrophobic species was formed on the micro/nano structures through perfluorosilane modification (PM). The reflectivity and hydrophobicity's influence mechanisms of structural height, duty cycle, and size are experimentally elucidated. The average reflectivity of the silicon surface in the visible light band is reduced to 3.0% under the optimal parameters, and the surface exhibits a large contact angle of 172.3 ± 0.8° and a low sliding angle of 4.2 ± 1.4°. Finally, the durability of the anti-reflection and superhydrophobicity is also confirmed. This study deepens our understanding of the principles of anti-reflection and superhydrophobicity and expands the design and preparation methods for self-cleaning and anti-reflective surfaces. [ABSTRACT FROM AUTHOR]

In specific applications like ice-repellent coatings or membrane separation technology, wettability is a key parameter affecting the applicability of commodity polymers. This study presents a technique to fine-control the wetting properties of a hierarchically structured polypropylene surface, enabling the transition between superhydrophobic and superhydrophilic states. To demonstrate the tunability of the wetting properties of polypropylene (PP) substrate, we prepared in a consecutive way superhydrophobic (advancing contact angle (CAadv) of 152°) and superhydrophilic (CAadv of 0°) material by solvent-treatment and mild air plasma treatment. The optimal plasma treatment parameters to achieve superhydrophilic wetting behaviour, which is stable for at least one week of storage in air was also explored. Water contact angle measurement and X-ray photoelectron spectroscopy were used to monitor the time dependency of hydrophobic recovery on a hierarchically structured PP surface. With a simple model considering structural and wetting parameters, we characterized the droplet spreading behaviour of plasma-treated roughened surfaces, which exhibited superhydrophilic wetting behaviour with equilibrium CAadv of nearly 0°. The proposed model, which aligns well with experimental data, can be used to compare the droplet spreading behaviour of plasma-treated roughened surfaces. [ABSTRACT FROM AUTHOR]

Owing to their excellent thermal conductivity (TC), boron nitride nanosheet (BNNS)-filled polymer composite films have aroused great interest in their use for heat dissipation in the electronics industry. However, the application of BNNS composite films is limited by their lack of hydrophobicity and non-fouling properties, as well as their low corrosion resistance, affecting their long-term stability in specific environments, such as high humidity environment, rainwater erosion, corrosion from pollutants, and dust pollution. In this work, a composite film with both superhydrophobicity and a high TC was constructed by spraying a silicon carbide (SiC) and polyurethane (PU) coating modified by perfluorooctylmethoxysilane (PFTMS) onto the surface of BNNS-filled polymer composite films. The PFTMS coupling agent not only improved the dispersibility of SiC in PU and the combination of SiC with PU, but also reduced the surface free energy of the film. The optimal mass ratio of SiC to PU for the SiC/PU composite coating was 1.2:1, resulting in superhydrophobic properties with a contact angle (CA) of 168.6 ± 1.3° and a rolling angle (RA) of 2.8 ± 1.2°. Meanwhile, SiC with higher TC also allowed the BNNS-filled composite films to maintain a high TC (32.3 W/m K). The composite films exhibited excellent TC and self-cleaning ability, as well as improved mechanical and chemical stability of the surface, which provides a strategy for enhancing the environmental adaptability of BNNS composite films and broadening their application scenarios. Superhydrophobic SiC/PU-coated BNNS composite films with excellent anti-fouling properties and high thermal conductivity [ABSTRACT FROM AUTHOR]

Abstract Wearable sensors have attracted considerable interest due to their ability to detect a variety of information generated by human physiological activities through physical and chemical means. The performance of wearable sensors is limited by their stability, and endowing wearable sensors with superhydrophobicity is one of the means to enable them to maintain excellent performance in harsh environments. This review emphasizes the imperative progress in flexible superhydrophobic sensors for wearable devices. Besides, the wettability principle and the mechanism of wearable sensors are briefly introduced to propose the combination of superhydrophobicity and wearable sensors. Next, superhydrophobic substrates for wearable sensors, including but not limited to, polydimethylsiloxane, polyurethane, gel, rubber, and fabric, are described in depth, and also the respective fabrication processes and performances. Moreover, the utility of superhydrophobic wearable sensors in a normal intelligent environment is described, highlighting their application in monitoring physiological signals, such as physical movement, pulse, vibration, temperature, perspiration, respiration, and so on. Finally, this review evaluates the challenges and dilemmas that wearable sensors must be overcome for further development and improve the functional performance of wearable sensors, paving the way for their expansion into advanced wearable sensing systems.

The paper presents an experimental study of an assembly of five stages of an electric centrifugal pump (ECP) installation, the flow part of which is modified according to the principles of biomimetics, namely using the “lotus leaf effect”. The object of the study was a 5A-35 ECP. The surfaces of the blade systems of impellers and guide devices of stages 5 A-35 were hydrophobized using the method of applying surfactant layers. The degree of impellers hydrophobicity was estimated by the wetting angle average value measured by three drops at three different points on the impeller surface. The impellers surface roughness under study was determined by the arithmetic mean profile deviation Ra and the profile height irregularities Rz. The issues related to the surfactant coating modification effect salt deposition and corrosion were studied. For this purpose, the surfaces of the original and modified impellers were subjected to intensive forced salt deposition as a result of prolonged exposure to saline solution. The conclusion about the samples corrosion resistance degree was made by changing their mass, which was due to the salt deposits formation during 15 hours of stay in solution, as well as using the drop method. Both methods have shown that the surfactant coating can serve as a salt deposition inhibitor, and the pump impeller modified by it has increased corrosion resistance. Thus, during comparative tests, a smaller mass of salt was deposited on the modified impeller sample during 15 hours of exposure in saturated saline solution than on the original sample. This indicates that the surfactant layer prevents the salt deposits fixation on the working surfaces of the pump stage. On the modified sample examined by the drop method, the indicator color changed in 20 minutes, and on the original one – in 2 minutes. Experimental studies have been carried out, during which the operation energy parameters of a five stages 5A-35 pumping package with initial and modified surfactant-coated impellers have been determined. The studies have shown a 2 % increase in efficiency in the pum-ping package of stages with modified impellers. The results of the study can be useful in the oil production, chemical industry, as well as in the housing and communal services sector.

Abstract In specific applications like ice-repellent coatings or membrane separation technology, wettability is a key parameter affecting the applicability of commodity polymers. This study presents a technique to fine-control the wetting properties of a hierarchically structured polypropylene surface, enabling the transition between superhydrophobic and superhydrophilic states. To demonstrate the tunability of the wetting properties of polypropylene (PP) substrate, we prepared in a consecutive way superhydrophobic (advancing contact angle (CAadv) of 152°) and superhydrophilic (CAadv of 0°) material by solvent-treatment and mild air plasma treatment. The optimal plasma treatment parameters to achieve superhydrophilic wetting behaviour, which is stable for at least one week of storage in air was also explored. Water contact angle measurement and X-ray photoelectron spectroscopy were used to monitor the time dependency of hydrophobic recovery on a hierarchically structured PP surface. With a simple model considering structural and wetting parameters, we characterized the droplet spreading behaviour of plasma-treated roughened surfaces, which exhibited superhydrophilic wetting behaviour with equilibrium CAadv of nearly 0°. The proposed model, which aligns well with experimental data, can be used to compare the droplet spreading behaviour of plasma-treated roughened surfaces.

The superhydrophobicity of submerged surfaces typically pertains to the trapped air film at the liquid–solid interface, subject to wettability transitions from a Cassie–Baxter state to more unstable states that gradually collapse to high retention regimes, which are energetically more favorable. In this work, the dynamic evolution of those transient metastable states is correlated to the underwater acoustic performance of laser textured superhydrophobic surfaces, resolving the dependence of the ultrasound spectral response with the immersion time to capture the genuine contribution of the hierarchical subwavelength morphology, regardless of the air layer effects. Acoustic wave attenuation of the incident ultrasound energy is extensively quantified in transmission, accounting for instantaneous broadband sound blocking (>30 dB) within the spectral range 0.5–1.5 MHz. As a result of the air layer detachment with the immersion time, transmission coefficients increase accordingly, while acoustic fields in reflection unexpectedly evolve toward stealthiness and naïve acoustic camouflage, mostly ascribable to dissipative mechanisms at air layer interfaces. The intrinsic decay of the air layer effect is tentatively determined at different frequencies, since quantitative understanding of the transient lifetime governing underwater surface wettability is critical to design stable superhydrophobic character of laser induced subwavelength metastructures on the most promising acoustic materials – from eco‐friendly natural to artificial. [ABSTRACT FROM AUTHOR]

This study examines the efficacy of icephobic polyurethane nanocomposite coatings in mitigating corrosion on an aluminum substrate. A titanium-based conversion coating is applied to modify the substrate, and the research focuses on optimizing the dual functionalities of icephobicity and anticorrosion within the polyurethane coatings while ensuring strong substrate adhesion. The coatings are formulated using fluoropolyol, isocyanate, and silica nanoparticles treated with polydimethylsiloxane. Surface properties are analyzed using contact angles, contact angle hysteresis measurements, and atomic force microscopy, and the coatings' icephobicity is evaluated through differential scanning calorimetry, freezing time delay, ice adhesion under impact and non-impact conditions, and ice accretion tests. The corrosion resistance and adhesive strength of the coatings are assessed using electrochemical impedance spectroscopy and cross-cut tests, respectively. Increasing the concentration of silica nanoparticles to 10 wt.% increases contact angles to 167°, although the 4 wt.% coating produces the lowest contact angle hysteresis (3° ± 0.5°) and ice nucleation temperature (−23 °C). The latter coating is then applied to a substrate pretreated with a titanium/cerium-based conversion coating. This prepared surface maintains an ice adhesion of about 15 kPa after 15 icing/de-icing cycles and provides approximately 90 days of surface protection (|Z|lf = 1.6 × 109 Ω·cm2). Notably, the impedance value exceeds that of untreated substrates, underscoring the effectiveness of the titanium/cerium-based conversion coating in enhancing both corrosion resistance and coating adhesion to the substrate. [ABSTRACT FROM AUTHOR]

The interaction of biomaterials with the immune system is ruled by the action of macrophages. The surface features of these biomaterials, like wettability, which is an expression of chemical composition, texture, and geometry, can affect macrophages response. Such surface parameters can be then efficiently exploited to improve biocompatibility by lowering undesired immunological reactions and at the same time creating the substrate for positive interactions. In this work, the preparation and physicochemical characterization of highly water-repellent surfaces to develop and characterize 3D spheroids derived from monocyte-macrophages (RAW 264.7 cell line) has been carried out. As a measure of cell viability over time, the obtained aggregates have been transferred under standard 2D cell culture conditions. Significant changes on the morphology-associated polarization of the derived cellular entities have been evaluated at the nanoscale through 3D profilometry. The results suggested that the spheroid formation using highly repellent substrates induced the activation of M2-type cells. This simple and cost-effective approach can be used for preparing M2-based macrophages for regenerative purposes. [ABSTRACT FROM AUTHOR]

In this study, we aimed at transforming naturally superhydrophilic Hanji, a traditional Korean Han paper into its superhydrophobic version. This change is crucial for applications requiring water damage resistance, such as mold growth, abrasion, and degradation. The resulting superhydrophobic Hanji shows potential for diverse applications, including fabricating wallpaper, traditional window covers, and high-end wrapping paper. To achieve this, ZnO nanoparticles (NPs) were deposited on the surface of Hanji via supersonic spraying, resulting in morphological curvatures capable of accommodating nanoscale air pockets. Additionally, supersonic spraying facilitated the robust adhesion of ZnO NPs to the Hanji cellulose fibers. Notably, the hydroxyl groups from both ZnO and Hanji were removed through subsequent annealing, resulting in superhydrophobic ZnO-Hanji. The annealing-induced shrinkage and densification of Hanji enhanced its superhydrophobicity, a property not achieved using regular A4 paper. This substantiated the unique benefits of using Hanji to realize superhydrophobicity. The superhydrophobicity reverted to superhydrophilicity upon exposure to ultra-violet irradiation, initiating reactions of the –OH group from atmospheric moisture with electron–hole pairs on the ZnO surfaces. Consequently, tunable/reversible wettability of ZnO-decorated Hanji was achieved via simple supersonic spraying and annealing, without any chemical modifications. [ABSTRACT FROM AUTHOR]

Conventional antireflective films for solar cells are usually porous for high transmittance, but still suffer from weak weatherability and poor hydrophobicity because water droplets can enter porous films easily and degrade the antireflection performance. In order to achieve a good balance between high transmittance and excellent hydrophobicity, superhydrophobic porous SiO2 bilayer film with refractive index gradient was designed. Mesoporous SiO2 film with high refractive index as inner layer was synthesized on the glass at first and then superhydrophobic porous SiO2 film with low refractive index was prepared by a facile sol-gel method using hexamethyldisilane (HMDS) as modifier. As HMDS content increases, the hydrophobicity of the upper layer was significantly improved while the transmittance was slightly decreased because the -OH on the layer were gradually replaced by -CH3. When volume ratio of HMDS to Alkali (VHMDS/Alkali) was 0.6, a large water contact angle (WCA) of 163.6° and high transmittance increase of 2.82% was obtained. When applying this film to the glass on the surface of perovskite solar cells, an obvious increase (0.78%) in photoelectric conversion efficiency (PCE) was obtained. Especially, the superhydrophobic SiO2 bilayer film exhibited a higher transmittance increase of 3.19% in the broad wavelength range of 380–1100 nm and larger WCA of 161°. In addition, after a 24-h immersion in a water bath at 80 °C, the transmittance was only reduced by 0.26%, indicating a good weatherability. Therefore, this work can provide a more innovative, superior, and facile method to prepare promising antireflection coatings for solar cells. Highlights: Superhydrophobic porous SiO2 bilayer film with refractive index gradient is prepared. The bilayer film shows high transmittance increase of 3.19% and larger WCA of 161°. The bilayer film exhibits good weatherability after immersion in water bath at 80 °C. [ABSTRACT FROM AUTHOR]

Despite the significant interest of researchers, icing of aircraft, vehicles, ships, and equipment of offshore oil structures remains to be an urgent problem. This paper considers the factors that promote a decrease in the strength of the contact between ice and surfaces under an applied shear load. The main attention is focused on studying the influence of the rate of shear loading on the fracture of the interfacial contact between ice and superhydrophobic coatings. The strength of the adhesive contact under the conditions of controlled variations in the applied load is measured using a technique based on the detachment of ice from a surface under the influence of centrifugal force. The study is carried out for large ensembles of samples in the temperature range from −5 to −20°C, thereby making it possible to evaluate the influence of the quasi-liquid layer and the Rehbinder effect on a decrease in the shear adhesive strength. The results obtained indicate that the contact between ice and a superhydrophobic coating is fractured through a mixed viscous–brittle mechanism. In this case, a decrease in temperature or an increase in the loading rate causes a transition from the viscous to the brittle fracture. These results indicate a potential acceleration of ice shedding with an increase in the growth rate of the shear stress. [ABSTRACT FROM AUTHOR]

Constructing a superhydrophobic coating on cement-based materials' surface can effectively inhibit the invasion of external water and corrosive ions. However, current strategies of fabricating superhydrophobic coatings often require complex processes and some harmful solvents. Herein, an eco-friendly method is proposed for constructing superhydrophobic coatings on mortar surfaces to inhibit water penetration and chloride ion corrosion. The superhydrophobic coating was fabricated using superhydrophobic zeolite powders modified with nontoxic stearic acid. The mortar with superhydrophobic coating (SHC-mortar) possesses a water contact angle of 156° and water slide angle of less than 10°. In addition, the self-cleaning, waterproof and anticorrosion properties of SHC-mortar were explored. The results show that the fabricated superhydrophobic coating endows the mortar with a self-cleaning property, significantly reduces the capillary water absorption of the mortar, and improves the anticorrosion property of the mortar. [ABSTRACT FROM AUTHOR]

Oil spill cleanup in water remains a critical challenge due to the harmful secondary pollution from conventional methods such as burning or chemical degradation. Herein, we present a facile method to fabricate a superhydrophobic and superoleophilic polyurethane (PU) foil for efficient and environmentally friendly oil/water separation. More specifically, micropillar arrays were embedded onto the foil surface through a nanoimprinting process. Microporous structures were generated at the foil cross-section by a supercritical carbon dioxide (CO2) saturation method. The dimensions of pillar and pore structures were optimized with the aim of boosting selective wetting (i.e., water repellency and oil attraction) properties. As a result, the developed PU foil shows an oil absorption efficiency nearly 4 times higher than a pristine reference. Moreover, the structured PU foil stably retains the absorbed oil for over a week, demonstrating an absorption capacity of nearly 400%, which is also much superior than the unstructured sample. Our concept of combining both topographical micropillars and cross-sectional micropores onto PU foil provides a novel approach for achieving efficient and environmental friendly oil/water separation. [ABSTRACT FROM AUTHOR]

Infrared reflective materials are pivotal in reducing bicarbon emission and have emerged as a global research focus. This study presents the preparation of kilogram-scale weakly Tb-doped cerium oxide nanocomposites, utilizing a green synthesis approach combining ball milling and high-temperature calcination. Integrating first-principles calculations with experiments analysis, we demonstrate that Tb doping enhances the band gap of cerium oxide, significantly improving its reflective properties. The resulting terbium-doped cerium oxide nanoparticles have good absorption in the visible range while maintaining excellent IR reflectance in the IR band. The near-infrared solar reflectance reaches 85.54 %. Additionally, we developed CeO 2 :Tb–SiO 2 polyester fabrics using an impregnation method. These fabrics show superior IR infrared barrier efficiency (76.58 %) and a notable reduction in inner-surface temperature compared to standard polyester fabrics. The barrier efficiency is enhanced by 27.59 %, and the temperature difference reaches up to 6.1 °C, underscoring their exceptional thermal insulating properties. Moreover, the fabric exhibits remarkable superhydrophobicity, with a contact angle of 152.1°. This novel heat-reflective, self-cleaning, stable rare-earth nano-insulating coating along with its application in polyester fabrics, paves the way for effective temperature regulation. Its potential applications in fabric stain and sun protection are promising, contributing to energy saving and sustainable development. [ABSTRACT FROM AUTHOR]

Rough structure microspheres developed using electrospinning show many superior properties, such as increased specific surface area and enhanced wettability, yielding numerous benefits to the applications in adsorption, separation, and others. In this study, biomimetic rough microspheres on string of polymethyl methacrylate nanofiber with hierarchical structure of micron-scale microsphere, and nanoscale Y-shape edges on the microsphere were innovatively and successfully developed by electrospinning. The resulting microsphere exhibited a steering-wheel-like Y shape, and the formation process was physically explained by the geometric potential theory. In the spinning process, irregular hexahedron-like droplet was firstly formed. Then, the hexahedron-like droplet changed to tetrahedron-like after the bottom contacted the collector. The tetrahedron-like droplet evolved into Y-shaped microsphere due to the geometric potential and the collapse of the center part owing to the solvent evaporation. Furthermore, similar to the natural lotus leaf, the hierarchical steering-wheel structure strengthened the nanofiber membrane roughness and endowed the membrane with superhydrophobicity, indicating the potential application in water treatment (oil-water separation, and dye and heavy metal ion adsorption), functional surface materials (self-cleaning fabrics), energy generation and other salient areas. [ABSTRACT FROM AUTHOR]

Zirconia (ZrO2) is a ceramic material with high-temperature resistance and good insulating properties. Herein, for the first time, the surface of ZrO2 was modified with docosanoic acid (DCA) to improve its self-cleaning and hydrophobic properties. This surface modification transformed the surface of ZrO2 from hydrophilic to superhydrophobic. A two-step spraying method was used to prepare the superhydrophobic surface of ZrO2 by sequentially applying a primer and a topcoat. The primer was a solution configured using an epoxy resin as the adhesive and polyamide as the curing agent, while the topcoat was a modified ZrO2 solution. The superhydrophobic surface of ZrO2 exhibited a contact angle of 154° and a sliding angle of 4°. Scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, and other analytical techniques were used to characterize the prepared zirconia particles and their surfaces. Moreover, results from surface self-cleaning and droplet freezing tests showed that DCA-modified ZrO2 can be well combined, and its coatings show good self-cleaning and anti-icing properties on TA2 bases. [ABSTRACT FROM AUTHOR]

Ice accumulation and proliferation adversely affect the activities of various residential, commercial, and polar research stations. Although significant efforts are devoted to preventing ice adhesion to various surfaces by developing various anti‐icing coatings, it is still necessary to enhance overall performance and durability. Herein, a facile approach is proposed for fabricating an icephobic coating on an aluminum 6061 (Al) substrate, by coating a poly(dimethylsiloxane) (PDMS)/ poly(tetrafluoroethylene) (PTFE) composite through a spin‐coating method, followed by sprinkling of SiO2 nanoparticles (NPs). Crosslinker/binder‐free adhesion between PDMS and PTFE is achieved by utilizing secondary‐induced electrostatic dipole‐dipole interactions, these interactions are supported by density functional theory (DFT) calculations as well as structural studies. Moreover, the controlled addition of PTFE powder to PDMS improves the water‐repellency, mechanical strength, and surface roughness of the coating. The self‐formation of the superhydrophobic state of the PDMS/PTFE composite is achieved by sprinkling SiO2 NPs. The sprinkled SiO2 NPs are protected by the PDMS/PTFE composite, which serves as a stress concentrator to achieve low ice adhesion. Furthermore, freezing at low temperatures can be delayed by controlling the heat flow rate, interfacial contact area, and surface texture. This indicates the feasibility of the proposed method for various promising anti‐icing applications. [ABSTRACT FROM AUTHOR]

Superhydrophobic materials are often inspired by nature, whereas metamaterials are engineered to have properties not usually occurring naturally. In both, the key to their unique properties is structure. Here, it is shown that a negative Poisson's ratio (auxetic) mechanical metamaterial can transform into a unique superhydrophobic material. When stretched, its surface has the counterintuitive property that it also expands in the orthogonal lateral direction. The change in the solid surface fraction as strain is applied is modeled, and it is shown that it decreases as the space between solid elements of the auxetic lattice expands. This results in a unique dependence of the superhydrophobicity on strain. Experimental models are constructed to illustrate the relationship between different states of strain and superhydrophobicity as the lattice transitions from an auxetic to a conventional structure. The findings offer a new approach to designing superhydrophobic materials for self‐cleaning surfaces, droplet transportation, droplet encapsulation, and oil–water separation. [ABSTRACT FROM AUTHOR]

Abstract The superhydrophobicity of submerged surfaces typically pertains to the trapped air film at the liquid–solid interface, subject to wettability transitions from a Cassie–Baxter state to more unstable states that gradually collapse to high retention regimes, which are energetically more favorable. In this work, the dynamic evolution of those transient metastable states is correlated to the underwater acoustic performance of laser textured superhydrophobic surfaces, resolving the dependence of the ultrasound spectral response with the immersion time to capture the genuine contribution of the hierarchical subwavelength morphology, regardless of the air layer effects. Acoustic wave attenuation of the incident ultrasound energy is extensively quantified in transmission, accounting for instantaneous broadband sound blocking (>30 dB) within the spectral range 0.5–1.5 MHz. As a result of the air layer detachment with the immersion time, transmission coefficients increase accordingly, while acoustic fields in reflection unexpectedly evolve toward stealthiness and naïve acoustic camouflage, mostly ascribable to dissipative mechanisms at air layer interfaces. The intrinsic decay of the air layer effect is tentatively determined at different frequencies, since quantitative understanding of the transient lifetime governing underwater surface wettability is critical to design stable superhydrophobic character of laser induced subwavelength metastructures on the most promising acoustic materials – from eco‐friendly natural to artificial.

Superhydrophobic surfaces offer innovative solutions, particularly in water/oil separation systems, as they repel water and attract oil, enabling efficient separation. The study aimed to analyze coatings developed on galvanized steel and aluminum, regarding their wettability in saline water and diesel oil, aiming for applications in the oil and gas industry. Specimens underwent texturizing, in-situ growth of layered double hydroxide (ZnAl-LDH) film and modification with stearic acid (STA). Both LDH films exhibited similar binary hierarchical structures of hexagonal petals and micrometric flowers, interconnecting along the surface, forming pores that allowed for air entrapment after STA modification. CA for saline water exceeded 150º, and for diesel oil was under 10º, characterizing the coatings as superhydrophobic and superoleophilic. The coatings show promising potential for water/oil separation using recyclable substrates and a simple, low-cost, environmentally friendly process.

Superhydrophobic coatings for umbrella canopies have the potential to solve the issue of rain residue. However, achieving both impalement resistance and mechanical robustness in these coatings poses a significant challenge and limits their practical applications. In this study, we propose a similar “pole erecting” method utilizing perfluorodecyl polysiloxane modified SiO2 nanoparticles (F-silica) as the pole and poly(dimethylsiloxane) (PDMS) as the screw to enhance impalement resistance and mechanical robustness, which is attributed to the three-tier hierarchical micro-/micro-/nanostructure bonded by PDMS, along with a reduction in aspect ratio. The obtained PDMS0.5-F-silica could withstand 150 min of water drop impacting (equivalent to approximately 19,000 water drops) and 60 s of 50 kPa water jetting, also showed exceptional endurance against various mechanical tests, including 200 cycles of reciprocating abrasion, 1000 cycles of Martindale abrasion and 200 cycles of tape peeling. Moreover, when applying the PDMS0.5-F-silica coating to umbrella canopies, we observed an absence of rain residue after subjecting the umbrella to 20 h rain. These findings are promising for the development and practical implementation of superhydrophobic coatings.

In this paper, hierarchical micro/nano structures composed of periodic microstructures, laser-induced periodic surface structures (LIPSS), and nanoparticles were fabricated by femtosecond laser processing (LP). A layer of hydrophobic species was formed on the micro/nano structures through perfluorosilane modification (PM). The reflectivity and hydrophobicity’s influence mechanisms of structural height, duty cycle, and size are experimentally elucidated. The average reflectivity of the silicon surface in the visible light band is reduced to 3.0% under the optimal parameters, and the surface exhibits a large contact angle of 172.3 ± 0.8° and a low sliding angle of 4.2 ± 1.4°. Finally, the durability of the anti-reflection and superhydrophobicity is also confirmed. This study deepens our understanding of the principles of anti-reflection and superhydrophobicity and expands the design and preparation methods for self-cleaning and anti-reflective surfaces.

Durable superhydrophobic anti‐erosion/anticorrosion coatings are highly demanded across various applications. However, achieving coatings with exceptional superhydrophobicity, mechanical strength, and corrosion resistance remains a grand challenge. Herein, a robust microstructure coating, inspired by the cylindrical structures situated on the surface of conch shell, for mitigating erosion and corrosion damages in gas transportation pipelines is reported. Specifically, citric acid monohydrate as a pore‐forming agent is leveraged to create a porous structure between layers, effectively buffering the impact on the surface. As a result, the coating demonstrates remarkable wear resistance and water repellency. Importantly, even after abrasion by sandpaper and an erosion loop test, the resulting superhydrophobic surfaces retain the water repellency. The design strategy offers a promising route to manufacturing multifunctional materials with desired features and structural complexities, thereby enabling effective self‐cleaning and antifouling abilities in harsh operating environments for an array of applications, including self‐cleaning windows, antifouling coatings for medical devices, and anti‐erosion/anticorrosion protection, among other areas. [ABSTRACT FROM AUTHOR]

To produce functional protective textiles with minimal environmental footprints, we developed durable superhydrophobic antimicrobial textiles. These textiles are characterized by a micro-pleated structure on polyester fiber surfaces, achieved through a novel plasma impregnation crosslinking process. This process involved the use of water as the dispersion medium, water-soluble nanosilver monomers for antimicrobial efficacy, fluorine-free polydimethylsiloxane (PDMS) for hydrophobicity, and polyester (PET) fabric as the base material. The altered surface properties of these fabrics were extensively analyzed using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometry (XPS), thermogravimetric analysis (TGA), and water contact angle (WCA) measurements. The antimicrobial performance of the strains was evaluated using Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. After treatment, the fabrics exhibited enhanced hydrophobic and antimicrobial properties, which was attributed to the presence of a micro-pleated structure and nanosilver. The modified textiles demonstrated a static WCA of approximately 154° and an impressive 99.99% inhibition rate against both test microbes. Notably, the WCA remained above 140° even after 500 washing cycles or 3000 friction cycles. [ABSTRACT FROM AUTHOR]

The antibacterial properties of cicada wings originate from hexagonally arranged pillar-like multi-functional nanostructures with species-dependent heights, which are super-hydrophobic and self-cleaning. In the present study, two cicada species with promising nanopillars were investigated in more detail. Selected methods were used to analyze the wing surfaces, including Atomic Force Microscopy, Scanning Electron Microscopy, and bacterial tests with live/dead staining. Verifying the antibacterial properties posed challenges, such as the bacteria concentration needed to confirm the antibacterial properties. These challenges will also impact the practical implementation of antibacterial nanostructures and support the findings of recent critical publications. [ABSTRACT FROM AUTHOR]

Passive radiative cooling is an energy-free cooling method by exchanging thermal radiation with the cold universe through the transparent atmospheric window. Spectrum tailoring of the radiative cooler is the key to daytime radiative cooling in previously reported works. In addition, radiative coolers with large-scale fabrication and self-cleaning characteristics should be further developed to improve their industrial applicability. Herein, we propose a bilayer radiative cooling coating with the superhydrophobic property and a scalable process, by covering TiO2/acrylic resin paint with a silica/poly(vinylidene fluoride-co-hexafluoropropylene) (SiO2/P(VdF-HFP)) composite masking layer. The strong Mie scattering in TiO2/acrylic resin paint contributes to high solar reflection, while the SiO2/P(VdF-HFP) masking layer is responsible for superhydrophobicity and synergetic solar reflection in the ultraviolet band, resulting in an effective solar reflectivity of 94.0 % with an average emissivity of 97.1 % and superhydrophobicity with a water contact angle of 158.9°. Moreover, the as-fabricated coating can be cooled to nearly 5.8 °C below the temperature of commercial white paint and 2.7 °C below the local ambient temperature under average solar irradiance of over 700 W m−2. In addition, yearly energy saving of 29.0 %–55.9 % can be achieved after the coating is applied to buildings in Phoenix, Hong Kong, Singapore, Guangzhou, and Riyadh. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) alloy with good biomechanical and biocompatible properties is considered to be a promising biodegradable material for various applications. However, Mg alloy that is chemically active tends to be corroded in a physiological environment. In this work, we proposed a laser–chemical surface treatment to combine laser surface structuring and stearic immersion treatment to enhance the anti-corrosion and antibacterial properties of Mg alloy. The effects of surface structuring, chemistry, and wettability were analyzed, and the performance of the proposed technique was evaluated in terms of corrosion resistance and antibacterial properties. The experiments showed the following: (1) surface structuring by laser-induced dual-scale micro/nanostructures produced superhydrophilicity, with a water contact angle (WCA) of 0° on the surface of the Mg alloy; (2) applying the stearic acid immersion changed the chemistry of the Mg alloy's surface and thus facilitated the wettability transition to superhydrophobicity, with a WCA of 160.1° ± 0.5°; (3) the proposed laser–chemical surface treatment enhanced corrosion resistance and stabilized the wettability of Mg alloy in a corrosive medium significantly; and (4) the proposed laser–chemical surface treatment enhanced the antibacterial properties of the Mg alloy greatly, with an improved antibacterial rate as high as 82.05%. This work proved that the proposed laser–chemical surface treatment was a simple, effective, and efficient technique to modulate and control the wettability and further improve the anti-corrosion and antibacterial properties of the Mg alloy. [ABSTRACT FROM AUTHOR]

Ice accumulation on outdoor surfaces tends to cause a series of serious accidents in extreme climates. In recent years, superhydrophobic coatings have garnered significant interest in the passive anti-icing field owing to their exceptional ability to repel water. However, these superhydrophobic coatings displayed inadequate anti-icing properties in conditions of low temperature and high humidity, as well as poor corrosion resistance after prolonged immersion. Herein, we prepared a series of modified graphene micropillar array superhydrophobic coatings that have various micropillar widths based on simple physical embossing and spraying techniques. These coatings combined the graphene nanosheets modified by perfluorodecyl triethoxysilane (AC-FAS) and the fluorocarbon varnish coating with a micropillar array structure to gain great superhydrophobicity and anti-icing properties. Among these, the average freezing delay time of the Q200G coating increased over 500 times relative to the unmodified Al surface (about 10 s), and its average deicing shear force was as low as 0.1 N. Meanwhile, the corrosion resistance increased steadily as the micropillar width decreased, based on the electrochemical impedance spectroscopy test results. More importantly, such facile fabrication methods and multi-functionality make superhydrophobic coatings hold great application prospects. [ABSTRACT FROM AUTHOR]

This work is devoted to studying the stability of polymer coatings formed from reactive copolymers of glycidyl methacrylate and fluoroalkyl methacrylates and applied onto textured aluminum and cotton textile surfaces. The stability is determined with respect to the action of aggressive media and mechanical stress. The resulting coatings provide the achievement of long-term stable heterogeneous wetting with initial contact angles as large as 170°, thus preventing the penetration of corrosive agents into the hierarchical structure. The study has shown the influence of the composition of the reactive copolymers containing 3–7 fluorine atoms in a monomer unit on the stability of the polymer coatings with respect to the prolonged exposure to media with different acidities, as well as to cavitation, and abrasive wear. [ABSTRACT FROM AUTHOR]

The global spread of multidrug-resistant (MDR) hospital-acquired pathogens is a serious problem for healthcare units. The challenge of the spreading of nosocomial infections, also known as hospital-acquired pathogens, including Pseudomonas aeruginosa, must be addressed not only by developing effective drugs, but also by improving preventive measures in hospitals, such as passive bactericidal coatings deposited onto the touch surfaces. In this paper, we studied the antibacterial activity of superhydrophilic and superhydrophobic copper surfaces against the P. aeruginosa strain PA103 and its four different polyresistant clinical isolates with MDR. To fabricate superhydrophilic and superhydrophobic coatings, we subjected the copper surfaces to laser processing with further chemosorption of fluorooxysilane to get a superhydrophobic substrate. The antibacterial activity of superhydrophilic and superhydrophobic copper surfaces was shown, with respect to both the collection strain PA103 and polyresistant clinical isolates of P. aeruginosa, and the evolution of the decontamination of a bacterial suspension is presented and discussed. The presented results indicate the promising potential of the exploitation of superhydrophilic coatings in the manufacture of contact surfaces for healthcare units, where the risk of infection spread and contamination by hospital-acquired pathogens is extremely high. [ABSTRACT FROM AUTHOR]

In recent years, superhydrophobic surfaces have attracted significant attention due to their promising applications, especially in ice prevention, reduction in air resistance, and self-cleaning. This study utilizes femtosecond laser processing technology to prepare different surface microstructures on polytetrafluoroethylene (PTFE) surfaces. Through experiments, it investigates the relationship between the solid–liquid contact ratio and surface hydrophobicity. The shape of water droplets on different microstructure surfaces is simulated using ANSYS, and the relationship between surface microstructures and hydrophobicity is explored in the theoretical model. A superhydrophobic surface with a contact angle of up to 166° was obtained by machining grooves with different spacings in polytetrafluoroethylene sheets with femtosecond laser technology. Due to the micro- and nanostructures on the surface, the oleophobicity of the processed oleophilic PTFE surface is enhanced. [ABSTRACT FROM AUTHOR]

Oil spills and industrial oily wastewater during petroleum and chemical production and transportation have caused serious damage to water resources and the environment. Therefore, it is of great significance to develop new materials and new methods for oil pollution control. Recently, polyurethane (PU) polymers have been proven to be promising candidates for the fabrication of superhydrophobic and superoleophilic materials for oil–water separation due to their low cost, strong absorptive capacity, good elasticity, and ease of large-scale manufacturing. In this review, we summarize the recent advances of superhydrophobic PU-based materials for oil–water separation. The synthesis methods of porous PU based two-dimensional (2D) membrane and three-dimensional (3D) foam are introduced. Furthermore, the strategies of modifying the PU-based foam to enhance its superhydrophobicity through the synergistic effect of increasing surface roughness and reducing surface energy are highlighted, which greatly promotes its application in oil–water separation. Finally, the common methods for the recycling of oil-absorbing materials are discussed. This work has important reference significance for PU-based materials in solving oil pollution.

A metallic surface can exhibit low wettability through the formation of a rough structure with micro/nanometric dimensions combined with a surface energy-reducing agent. When the contact and sliding angles are ≥ 150° and ≤ 10°, respectively, the surface is classified as superhydrophobic (SHS). The study aimed to electrodeposit a microstructure with micronanometric roughness of nickel, stearic acid (Al/Ni-SA), and nickel, stearic acid with multi-layered carbon nanotubes (Al/Ni-SA-MWCNT) on aeronautical aluminum 7050. The obtained contact angles were close to 160°, and sliding angles were less than 1°, characterizing the superhydrophobic and self-cleaning nature. Freezing tests were conducted, and the deposit with MWCNT showed longer freezing times at -22°C. The Al/Ni-SA-MWCNT condition also exhibited the best corrosion resistance with corrosion current superior by two orders of magnitude compared to the Al/Ni-Sa condition. The coatings demonstrated impressive performance, achieving corrosion inhibition efficiencies close to 100%.

Abstract Ice accumulation and proliferation adversely affect the activities of various residential, commercial, and polar research stations. Although significant efforts are devoted to preventing ice adhesion to various surfaces by developing various anti‐icing coatings, it is still necessary to enhance overall performance and durability. Herein, a facile approach is proposed for fabricating an icephobic coating on an aluminum 6061 (Al) substrate, by coating a poly(dimethylsiloxane) (PDMS)/ poly(tetrafluoroethylene) (PTFE) composite through a spin‐coating method, followed by sprinkling of SiO2 nanoparticles (NPs). Crosslinker/binder‐free adhesion between PDMS and PTFE is achieved by utilizing secondary‐induced electrostatic dipole‐dipole interactions, these interactions are supported by density functional theory (DFT) calculations as well as structural studies. Moreover, the controlled addition of PTFE powder to PDMS improves the water‐repellency, mechanical strength, and surface roughness of the coating. The self‐formation of the superhydrophobic state of the PDMS/PTFE composite is achieved by sprinkling SiO2 NPs. The sprinkled SiO2 NPs are protected by the PDMS/PTFE composite, which serves as a stress concentrator to achieve low ice adhesion. Furthermore, freezing at low temperatures can be delayed by controlling the heat flow rate, interfacial contact area, and surface texture. This indicates the feasibility of the proposed method for various promising anti‐icing applications.

Superhydrophobic materials are often inspired by nature, whereas metamaterials are engineered to have properties not usually occurring naturally. In both, the key to their unique properties is structure. Here, it is shown that a negative Poisson's ratio (auxetic) mechanical metamaterial can transform into a unique superhydrophobic material. When stretched, its surface has the counterintuitive property that it also expands in the orthogonal lateral direction. The change in the solid surface fraction as strain is applied is modeled, and it is shown that it decreases as the space between solid elements of the auxetic lattice expands. This results in a unique dependence of the superhydrophobicity on strain. Experimental models are constructed to illustrate the relationship between different states of strain and superhydrophobicity as the lattice transitions from an auxetic to a conventional structure. The findings offer a new approach to designing superhydrophobic materials for self‐cleaning surfaces, droplet transportation, droplet encapsulation, and oil–water separation.

Passive radiative cooling is an energy-free cooling method by exchanging thermal radiation with the cold universe through the transparent atmospheric window. Spectrum tailoring of the radiative cooler is the key to daytime radiative cooling in previously reported works. In addition, radiative coolers with large-scale fabrication and self-cleaning characteristics should be further developed to improve their industrial applicability. Herein, we propose a bilayer radiative cooling coating with the superhydrophobic property and a scalable process, by covering TiO2/acrylic resin paint with a silica/poly(vinylidene fluoride-co-hexafluoropropylene) (SiO2/P(VdF-HFP)) composite masking layer. The strong Mie scattering in TiO2/acrylic resin paint contributes to high solar reflection, while the SiO2/P(VdF-HFP) masking layer is responsible for superhydrophobicity and synergetic solar reflection in the ultraviolet band, resulting in an effective solar reflectivity of 94.0 % with an average emissivity of 97.1 % and superhydrophobicity with a water contact angle of 158.9°. Moreover, the as-fabricated coating can be cooled to nearly 5.8 °C below the temperature of commercial white paint and 2.7 °C below the local ambient temperature under average solar irradiance of over 700 W m−2. In addition, yearly energy saving of 29.0 %–55.9 % can be achieved after the coating is applied to buildings in Phoenix, Hong Kong, Singapore, Guangzhou, and Riyadh.

The interaction of biomaterials with the immune system is ruled by the action of macrophages. The surface features of these biomaterials, like wettability, which is an expression of chemical composition, texture, and geometry, can affect macrophages response. Such surface parameters can be then efficiently exploited to improve biocompatibility by lowering undesired immunological reactions and at the same time creating the substrate for positive interactions. In this work, the preparation and physicochemical characterization of highly water-repellent surfaces to develop and characterize 3D spheroids derived from monocyte-macrophages (RAW 264.7 cell line) has been carried out. As a measure of cell viability over time, the obtained aggregates have been transferred under standard 2D cell culture conditions. Significant changes on the morphology-associated polarization of the derived cellular entities have been evaluated at the nanoscale through 3D profilometry. The results suggested that the spheroid formation using highly repellent substrates induced the activation of M2-type cells. This simple and cost-effective approach can be used for preparing M2-based macrophages for regenerative purposes.

Composite coatings or films with polytetrafluoroethylene (PTFE) are typically utilized to offer superhydrophobic surfaces. However, the superhydrophobic surfaces usually have limited durability and require complicated fabrication methods. Herein, we report the successful integration of PTFE with ZnO ceramics to achieve superhydrophobicity via a one-step sintering method, cold sintering process (CSP), at 300 ℃. (1–x) ZnO–x PTFE ceramic composites with x ranging from 0 to 70 vol% are densified with relative density of over 97%. Micro/nano-scale PTFE polymer is dispersed among ZnO grains forming polymer grain boundary phases, which modulate surface morphology and surface energy of the ZnO–PTFE ceramic composites. For the 60 vol% ZnO–40 vol% PTFE ceramic composite, superhydrophobic properties are optimized with static water contact angles (WCAs) and sliding angles (SAs) of 162° and 7°, respectively. After abrading into various thicknesses (2.52, 2.26, and 1.99 mm) and contaminating with graphite powders on the surface, WCA and SA are still maintained with a high level of 157°–160° and 7°–9.3°, respectively. This work indicates that CSP provides a promising pathway to integrate polymers with ceramics to realize stable superhydrophobicity.

Abstract Durable superhydrophobic anti‐erosion/anticorrosion coatings are highly demanded across various applications. However, achieving coatings with exceptional superhydrophobicity, mechanical strength, and corrosion resistance remains a grand challenge. Herein, a robust microstructure coating, inspired by the cylindrical structures situated on the surface of conch shell, for mitigating erosion and corrosion damages in gas transportation pipelines is reported. Specifically, citric acid monohydrate as a pore‐forming agent is leveraged to create a porous structure between layers, effectively buffering the impact on the surface. As a result, the coating demonstrates remarkable wear resistance and water repellency. Importantly, even after abrasion by sandpaper and an erosion loop test, the resulting superhydrophobic surfaces retain the water repellency. The design strategy offers a promising route to manufacturing multifunctional materials with desired features and structural complexities, thereby enabling effective self‐cleaning and antifouling abilities in harsh operating environments for an array of applications, including self‐cleaning windows, antifouling coatings for medical devices, and anti‐erosion/anticorrosion protection, among other areas.

This study reports the surface coating of fluorine-free hexamethyldisilazane (HMDS) on non-porous silica particles (SPs) and mesoporous silica particles (MSPs), with nanopores arranged in the straight channels, and compares the degree of superhydrophobicity by coating them on biodegradable PLA film by gravure process. The particle sizes of SPs and MSPs are 50 nm and 800 nm, and the amount of HMDS grafted onto SPs and MSPs is 0.5% and 9.5%, respectively. The superhydrophobicity of these particles is confirmed by the measurement of water contact angle (WCA) as a function of HMDS concentration for SPs and MSPs from 0 to 1.6 M, respectively. The WCA of HMDS@SPs and HMDS@MSPs grafted with 1.6 M of HMDS is 152° and 151° (WCA of unmodified SPs and MSPs is 13.85° and 27.65°). To apply superhydrophobic PLA film coating, 5 wt% of HMDS@SPs and HMDS@MSPs were mixed with gravure solution and then coated on biodegradable polylactic acid (PLA) film. The results showed that the WCA of PLA film with HMDS@SPs and HMDS@MSPs were 98.40° and 152.31°, respectively. This remarkable difference in WCA is due to the dissociation of HMDS molecules grafted on the surface of SPs and MSPs, which are easily separated by the gravure solvent. For MSPs materials composed of many nanopores, the dissociated HMDS molecules are initially released into the solution but are retained within the nanopores. Therefore, the residual amount of HMDS molecules dissociated by the gravure solution is much higher in HMDS@MSPs than in HMDS@SPs.

Cerium myristate nanoparticles were introduced as a superhydrophobic, anticorrosive additive for protecting steel corrosion in the marine medium. Cerium myristate nanoparticles with hydrophobic characteristics were synthesized via a facile strategy. The microscopic analysis revealed square-shaped cerium myristate nanoparticles. Cerium myristate-epoxy coatings exhibited a maximum contact angle (151.7°) at 15 wt% myristic acid. The surface analysis of the coatings through atomic force microscopy (AFM), determined the roughness factor Ra = 216 nm. The superhydrophobic epoxy coatings significantly minimized the contact area of steel and corrosive medium and beneficiated a three-fold increment in the corrosion resistance than bare epoxy coating. The electrochemical analysis of the coating provided conclusive evidence for the above. In addition, the prepared coating exhibited excellent self-cleaning ability, providing further advantage to protect the coating from external contaminants in seawater. The present work established a fluorine free, self-cleaning, anticorrosive and superhydrophobic cerium myristate deposited epoxy coating through a simple route for protecting steel from marine environment.