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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]

Individuals suffering from voice disabilities have limited access to currently available automation technologies that operate through voice commands. To address this issue, an alternative voice recognition approach is essential without directly monitoring the audio signals generated from the vocal cord. In this work, the design of a chemically reactive and conductive sponge is reported to create an underwater vibration sensor with a fast response time and high sensitivity, through orthogonal modulation of conductivity (40–2150 kΩ), water repellence (0°–154°) and mechanical properties (0.32–2.63 MPa). This class of porous sponge sensors enables the identification of subtle water waves generated at the air–water interface and extends its utility to detecting a variety of locomotion (squatting, jumping, walking, etc.), as well as automated voice recognition using a deep learning model without direct contact with the human body. Overall, this underwater vibration sensor provides a novel basis for remote interaction with automated technologies, which finds use in medical diagnostics, human‐machine interfaces, and underwater communication systems. [ABSTRACT FROM AUTHOR]

A new strategy for multifunctional coatings with flame retardancy, superhydrophobicity and UV shielding ability on cotton fabrics (SFR cotton) was realized by step-by-step spraying ammonium phytate, lignin and hybrid nanoparticles of polydimethylsiloxane (PDMS) modified mesoporous silica nanoparticles (MSNs) with entrapped Fe2O3 (PDMS@Fe2O3-MSNs). The surface adhesion PDMS@Fe2O3-MSNs constructed micro/nano-scale surface structure on SFR cotton fabric, which endowed superhydrophobic (WCA = 152 ± 1.3°), anti-fouling and self-cleaning properties. Benefiting from the synergistic effects of the physical barrier provided by the PDMS@Fe2O3-MSNs and the intumescent flame-retardant properties of ammonium phytate and lignin, the SFR cotton fabric demonstrated excellent self-extinguishing performance under an open fire and left a char layer with 8.4 cm. In addition, due to the excellent UV-absorption ability of lignin and Fe2O3 nanoparticles, the SFR cotton fabric was able to shield the UV irradiation damages to rat skin. Furthermore, the SFR cotton fabric demonstrated remarkable durability against rigorous conditions, including ultrasonic washing, sandpaper abrasion, UV irradiation and exposure to strong acid/alkali environments. After 150 min of ultrasonic washing and 50 cycles of abrasion, the SFR cotton fabric could preserve its hydrophobicity, flame retardancy and UV shielding ability. In addition, the SFR cotton fabric delivered exceptional chemical stability and UV durability when exposed to strong acid/alkali for 24 h and UV irradiation (200 W) for 12 h, respectively. Significantly, the SFR cotton fabric could retain the original flexibility and breathability of pristine cotton fabric. Therefore, the simple and feasible strategy of multifunctional coatings has broad application prospects in advanced multifunctional textiles, military facilities and other fields. [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]

1,2,3,4,5,6,7,8‐Octamethylcyclotetrasilazane (OTMSD), a cyclic silazane precursor, is deposited via atmospheric pressure plasma onto a substrate. The resulting coating exhibits a dual surface roughness, contributing to a significant reduction of surface wettability. Notably, the coating exhibits superhydrophobic characteristics, proven by a water contact angle of approximately 170°, hysteresis angle below 10°, very low tilting angle (<10°), and droplet‐bouncing effect. Importantly, this superhydrophobicity is achieved using OTMSD as fluorine‐free precursor with low reactivity to water. Furthermore, the deposition process is carried out using a commercially available plasma device highlighting its practicality and scalability for large‐scale production. [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]

A superhydrophobic cylinder is a circular cylinder with a boundary pattern of alternating shear-free menisci and solid portions. This article derives analytical solutions for the torque-driven Stokes flow around a superhydrophobic cylinder that is free to move, or 'swim', subject to the constraint that it is free of net force. The mathematical approach is a natural generalization of one used to solve for transverse shear flow over a superhydrophobic surface comprising a periodic array of no-shear slots (Crowdy 2011 Phys. Fluids23 (doi:10.1063/1.3605575)). First, the torque-driven Stokes flow around a superhydrophobic cylinder with two unequal no-shear menisci and two equal solid portions is solved in detail. It is then shown how that analysis generalizes, in a natural way, to a cylinder with M no-shear menisci between M solid portions with full exposition given of the case of M=3 equal solid portions. A further generalization to flow around a superhydrophobic cylinder with an N -fold rotationally symmetric patterning with M menisci in each 2π/N sector is made. Torque-driven superhydrophobic cylinders with a no-shear pattern devoid of any rotational symmetry are shown to swim on circular trajectories with formulas for the radius and cylinder angular velocity on these trajectories derived here as functions of the no-shear pattern geometry. The M=1 case of a 'Janus' superhydrophobic cylinder having one meniscus and one solid portion can be solved completely explicitly. [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]

Here, we developed a lotus-leaf-resembling superhydrophobic coating with sturdy abrasion and weather resistance. By taking the sturdiness of the superhydrophobicity into account, this coating was created by incorporating a zinc-mediated superhydrophobic surface that was rough and ultraviolet-resistant into a polyurethane layer capable of strong wear resistance. By spraying the zinc-mediated perfluorosilane and a polyurethane suspension onto an aluminum flake, the lotus-leaf-resembling superhydrophobic coating was thus prepared. The resulting coating displayed the natural superhydrophobic phenomena with a contact angle of up to 157.1° and a rolling angle of 4.2°, greater or smaller by depending on the dosage of zinc. The adoption of zinc to the prepared coating not only mediated the rough surface texture but also extra granted the ultraviolet resistance. In couple with the strong wear resistance of the substrate layer, the proposed superhydrophobic coating provided the expected sturdy abrasion and weather resistance. The development of the superhydrophobic coating shares a prospect with practical applications, especially outdoor applications. [ABSTRACT FROM AUTHOR]

Hydrogen‐bonded organic frameworks (HOFs) are a new class of crystalline porous organic molecular materials (POMMs) with great potential for a diverse range of applications. HOFs face common challenges to POMMs, and in general to purely organic crystals, that is, the difficulty of integrating complexity in crystals. Herein, we propose a simple and sequential strategy for the formation of HOFs with hierarchical superstructures. The strategy is based on controlling the assembly conditions, avoiding the use of any surface functionalization or template, which allows to obtain hierarchical crystalline porous superstructures in an easy manner. As proof of concept, we obtained the first example of core–shell (HOF‐on‐HOF) crystals and HOFs with hierarchical superstructures having superhydrophobicity and trapping abilities for the capture of persistent water contaminants such as oils and microplastics. We expect that this strategy could serve as inspiration for the construction of more intricate multiscale structures that could greatly expand the library of HOF materials. [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]

Thermal insulating coatings have important potential for energy saving in the field of building thermal management, but they are difficult to apply on a large scale due to the problem of being waterproof and moistureproof. Herein, we design a two-step spray process to fabricate a thermal insulating superhydrophobic composite coating using epoxy resin mixed with hollow glass microsphere as primer coating and fluorine-modified SiO2 nanocoating as a waterproof layer. The composite coating shows durable superhydrophobicity and low thermal conductivity [0.051 W/(m·k)], which is endowed with excellent thermal insulating properties under light and heat, contact heat conduction (− 20 to 70 °C), and boiling water scouring environment. These multiple key properties that have been integrated into our composite film are expected to provide unique advantages for applications in building thermal management. [ABSTRACT FROM AUTHOR]

There is an increasing demand for superhydrophobic surfaces due to their unique properties like self-cleaning, anti-icing, corrosion resistance, etc. The development of polyurethane (PU)-based superhydrophobic coating has garnered significant attention for aircraft applications. Polyurethane (PU) topcoat is widely used in aircraft and is hydrophilic in nature with a water contact angle (WCA) of 75 ± 3°. In the present work, a hydrophilic PU clear coat on aircraft-grade aluminum substrate is transformed to a superhydrophobic (SHP) surface by spraying environmentally friendly hydrophobically modified silica nanoparticles (HSiNps) oonto a PU layer that was partially cured in a hot air oven at 60°C for 1.5 h. The SHP surface exhibited a WCA of 162 ± 3° and a sliding angle (SA) of 8 ± 3°. With the incorporation of HSiNps, micro – nano dual-scale surface roughness is created and the surface roughness of the PU coating is increased from 0.35 to 2.42 µm. The coating exhibits good adhesion (5B) with excellent water repelling property and remains thermally stable and superhydrophobic even after subjecting it to 100°C for one week. Durability of the coatings is studied by immersing the coatings in various liquids. The retention of superhydrophobic property after anti-fogging, water sprinkler, and sand paper abrasion tests further demonstrate the robustness of the coating. Polyurethane-based SHP coating is prepared using hydrophobized silica nanoparticles. Partially cured polyurethane coating help in grafting of silica nanoparticles on to the surface. The coatings are durable to heat, solvents, corrosive liquids and sand paper abrasion [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.

[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 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]

Non‐contact intelligent sensing technology is a key player in the data acquisition and environmental monitoring framework of the Internet of Everything, laying the groundwork for the realization of highly integrated intelligent network systems. However, environmental factors continue to be a major challenge in the process of real‐time monitoring and feedback of objects, constraining the stability and accuracy of the sensing signals. In this study, a hierarchical spatial assembly strategy is implemented to effectively integrate an intermediate energy storage layer with superhydrophobic surfaces (CA = 162 ± 2.5°), resulting in the development of a moisture‐resistant triboelectric structural materials with stable monitoring and tracking capabilities. The moisture‐resistant self‐powered sensor constructed from this triboelectric structural material operates effectively in extreme humidity conditions (99% RH) with a full‐scale output retention rate of 95.2%, and is capable of accurately sensing human activity from the distance of 3 m. Importantly, the sensor can also effectively detect vehicle states during operation and perform real‐time monitoring of the vehicle's surrounding environment. This study not only overcomes the long‐standing challenges of accuracy and stability in high humidity for sensors but also advances the development of sustainable, interconnected intelligent systems for the Internet of Everything in extreme environmental conditions. [ABSTRACT FROM AUTHOR]

Herein, an anticorrosive and hydrophobic surface for Ti–6Al–4V was prepared through one-step anodic etching. The results showed that wettability was adjusted by current density and etching time. In particular, the maximum water contact angle (WCA) reached ~ 160.9° at a current density of 0.25 A cm−2 for 420 s. Energy dispersive spectroscopy and X-ray photoelectron spectroscopy showed the existence of spontaneous surface passivation, which was also verified by Tafel curves. In addition, Ecorr and icorr exhibited good anticorrosion properties on the surface of the Ti–6Al–4V after anodic etching. Furthermore, the change in surface adhesion was consistent with the change in the WCA after anodic etching. In conclusion, the one-step anodic etching can provide a convenient way to realize anticorrosion and superhydrophobic Ti–6Al–4V surface. Highlights: A superhydrophobic surface can be formed on Ti–6Al–4V substrate through one-step anodic etching. The maximum WCA of the surface reached ~ 160.9°. The change tendency of the adhesive force is contrary to that of the WCA. The large area and low-cost anticorrosive property of Ti–6Al–4V can be adjusted by current density. [ABSTRACT FROM AUTHOR]

Heterogeneous crystallization resulted in low conversion efficiency and short service life has become one of the important challenges of desalination. Here, a fluoro-modified CNT@epoxy composite coating is developed to durably inhibit salt crystallization of photothermal sheet even in highly concentrated salt water. Typically, it can have stable evaporation efficiency of ∼ 1. 7 0 kg ⋅ m − 2 ⋅ h − 1 without salt crystallization after continuously being operated for 40 cycles under one solar intensity in the 20 wt.% NaCl solution. That is mainly due to the Cassie state superhydrophobicity that can large increase the heterogeneous nucleation barrier quite close to the homogeneous one in salt water. This study expects to solve the existing problems of complex structure and short service time of seawater desalination units. We have constructed a photothermal sheet using superhydrophobic CNT@epoxy composite coating. It showed excellent photothermal conversion ability to inhibit heterogeneous crystallization, which it can maintain (∼1.70 kg.m–2.h–1) in salt water with high concentrations of NaCl (5–25 wt.%), even after continuous evaporation for 40 cycles in 20 wt.% NaCl solution. [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]

Bio‐inspired unidirectional flow of tiny aqueous droplets across the fibrous substrate paved the way for the emergence of various advanced materials. In the past, textiles decorated with noncontact‐based wettability‐patterns enabled unidirectional water flow—without flooding the top surface by the transferred water. However, such approaches mostly suffer from a low (≈0.176 µL mm−2 s−1) flow rate and are likely to delay the overall liquid ejection process. Here, a chemically reactive coating capable of tailoring water wettability (121.3° ± 2.4° to 153.3° ± 1.8°) is introduced on commercially available textiles to develop chemically modulated wettability‐pattern for achieving a rapid (2.57 ± 0.28 µL mm−2 s−1) flow rate of water against the gravity with an ability to roll the accumulated liquids on the top surface. The spatially selected and controlled chemical modification with hydrophilic and hydrophobic small molecules through a 1, 4‐conjugate addition reaction yielded a 3D channel with a customized wettability gradient. The pinning and depinning of invaded water through such chemically decorated channels enabled unidirectional and fast penetration of liquid, where the water penetration resistance largely depends on the water penetration direction and dimension of the chemically modulated channels. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA) was injected into test sheets and then dipped in a suspension of xylene and trimethylol propyl silane (95/5) containing titanium dioxide (TiO2) nanoparticles (NPs) at 65 and 85 °C for 3, 7, 10 and 15 s. TiO2 NPs aggregates coated the sheet surfaces after dipping. The camera photos and the static water contact angle (WCA) showed that the dip-coating transformed all the hydrophilic surfaces into hydrophobicity, and especially that the sheet with retention of 85 °C and 7 s exhibited superhydrophobicity, while the water droplets on the 65 °C sheets were in pinning state. The water droplets rolled off the superhydrophobic surface at tilt angles below 3°, showing self-cleaning. The retention period of 7 s was suitable, as it achieved the highest surface hydrophobicity regardless the retention temperature. The images of scanning electron microscope (SEM) and optical microscopes demonstrated the deposition of TiO2 NPs aggregates on the sheet surface and the formation of the porous structure on the surface. The combination of the aggregates with nanoscale protrusions and the pores with nanoscale pore walls constituted a hierarchical structure. The retention temperature of 65 °C made the pores shallow and wide, and the TiO2 concentration of 2% instead of 1% caused the excessive TiO2 NPs aggregates to cover the PLA substrate, reducing the WCA. The wetting models of water droplets on the surfaces of the 65 and 85 °C sticks were classified as Wenzel and Cassie states, respectively. [ABSTRACT FROM AUTHOR]

In this work, we developed a novel harp structure that collects water directly from fog in comparison with conventional Raschel mesh. Polyethylene (PE) monofilament was used as a collector's element in the harp. The Raschel mesh in its particular design is quite anisotropic, shows elastic behavior breadth-wise while no stiffness is exhibited in transverse direction. A comparison of fog collection yield for the harp signifies that fog harvesting rate is four times higher than Raschel mesh, suggesting some alterations in monofilament diameter and collector element. Therefore, harp technology with cylindrical monofilaments can be deployed commercially to increase the efficiency of fog collectors, where mass and velocity of fog are inappropriate for Raschel mesh. In addition, silane-coated harp showed that surface hydrophobicity further enhances fog collection efficiency. The fog collector element (FCE) after silane coating significantly enhanced fog water collection yield. Samples were characterized by high resolution scanning electron microscope (HR-SEM), energy-dispersive x-ray (EDX) and atomic force microscope (AFM). Hydrophobicity was analyzed by static water contact angle and water collection yield. [ABSTRACT FROM AUTHOR]

Microencapsulation technology is a versatile approach that offers effective protection for core materials while also solving issues such as leakage and interface bonding. In this study, a simple yet efficient method for producing multifunctional fabric coatings has been proposed by utilizing chitosan/silica hybrid microcapsules. The synthesis of the microcapsules was achieved through a combination of the single condensation method and the sol-gel method. These microcapsules were specifically designed to encapsulate octadecane and paraffin. The microcapsules were structured with a core-shell configuration, and the shell was functionalized with both fluoroalkyl silane (FAS) and choline phosphate (CP) grafts. The resulting microcapsules were added to silicone resins to produce multifunctional fabric coatings. The desired coatings improved the hydrophilic and hydrophobic properties of the fabrics, with a hydrophilic side contact angle of less than 10 ° and a hydrophobic side contact angle of up to 156 °. In addition, compared with untreated fabrics, coated fabrics can achieve a temperature difference of over 6 °C, demonstrating certain thermal insulation properties. Moreover, the coated fabric exhibits excellent antibacterial properties, with an inhibition rate of over 98% against Escherichia coli and Staphylococcus aureus. The proposed method provides a promising solution for developing advanced multifunctional fabrics with enhanced properties. [ABSTRACT FROM AUTHOR]

The icing phenomenon in nature can cause serious economic losses and security concerns. Eco-friendly anti-icing and deicing surfaces have been developed to address these issues. In this study, a photothermal superhydrophobic coating was fabricated by a facile polymerization process in the presence of micro–nano structured SiO2/TiN particles followed by a two-step spraying technology. The optimal coating displays remarkable superhydrophobic performance with a water contact angle of 159.1° and a water roll-off angle as low as 1.2°; it survives tape peeling, Taber abrasion, and solution immersion and demonstrates weather and corrosion resistance. More importantly, the SiO2/TiN coating shows excellent anti-icing/deicing property and can withstand multiple icing/thawing cycles. The excellent anti-icing/deicing performance is attributed to the robust superhydrophobic surface and the photothermal effect of TiN nanoparticles. Our fluorine-free design strategy provides important guidance for actual large-scale eco-friendly anti-icing/deicing application. [ABSTRACT FROM AUTHOR]

To alleviate the environmental hazard and minimize the practice of utilizing fossil fuel‐based precursors in the production of benzoxazines, sustainable bio‐phenol precursors namely magnolol and bio‐based amine furan‐2yl‐methanamine have been utilized to synthesize bio‐benzoxazine and was cured and characterized. The curing temperature of the synthesized bio‐benzoxazine monomer was found to be 216°C. Utilizing the carbon obtained from two different bio‐sources namely, chicken feather and cashew nut shell cake bio‐polybenzoxazine composites were prepared. The char yield of bio‐carbon reinforced bio‐polybenzoxazine composites was enhanced to 65% compared to that of neat polybenzoxazine (60%). The value of the dielectric constant of neat polybenzoxazine was found to be 5.52 which was further improved to a maximum of 8.9 and 7.8 on reinforcement of 15 wt% chicken feather carbon and 15 wt% cashew nut shell cake carbon respectively. The prepared bio‐polybenzoxazine composites exhibit a near superhydrophobic nature with the value of water repulsive angle at 150° than that of neat matrix (143°). From the obtained results, it is suggested that the sustainable bio‐carbon reinforced bio‐based benzoxazine will be a promising material for thermally stable, high dielectric, and water‐repellent applications. Highlights: Eco‐friendly, sustainable magnolol‐based bio‐benzoxazine was synthesized.Waste valorization for bio‐carbon—poultry, and agricultural wastes were utilized.Bio‐carbon reinforcement marginally increases the thermal stability of composites.Bio‐carbon reinforced composites exhibit close to superhydrophobic nature.Incorporation of bio‐carbon enhances the value of dielectric constant. [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]

Most superhydrophobic surfaces contain fluorine, which is very harmful to the environment. So, it is necessary to change the situation. This paper explains that a simple and fluorine-free plasma technology for superhydrophobic modification of silk fabrics by using one-sided protection method and low-temperature plasma induced grafting polymerization of octamethyl-cyclotetrasiloxane (D4) to form the superhydrophobic films. Treated silk and pristine silk fabrics were measured using field emission scanning electron microscopy(FESEM), Fourier-transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), and water contact angle measurement. The test results showed that the polymer films could be successful coated on the silk fibers surface via the low-temperature plasma. In addition, it has good durability, thermal stability, and a water contact angle of 152°. [ABSTRACT FROM AUTHOR]

Electrical discharge coating (EDC) process has been used to prepare a corrosion and wear resistant super-hydrophobic coating on the steel substrate. The coating process has been carried out by using three types of green compact tool electrodes (WS2/Cu, MoS2/Cu, and hBN/Cu). In these tool electrodes, powder mixing ratios (40:60, 50:50, 60:40) are varied, and their effect on coating characteristics (surface morphology, wettability, corrosion, and wear behaviour) has been studied. In this investigation, the morphology and chemical state of coating has been observed by using a scanning electron microscopy (SEM) and X-ray photoemission spectroscopy (XPS). SEM images of the applied coating show a porous and hierarchical structure. This hierarchical structure helps in raising the contact angle (CA) to 165.6° (super-hydrophobic state). The XPS analysis reveals that the deposition of solid lubricants takes place with their negligible disintegration into non-lubricating compounds. In addition, the prepared coating exhibits excellent resistance to wear and corrosion. [ABSTRACT FROM AUTHOR]

Nowadays, the low hydrophobicity and separation efficiency of original electrospun carbon nanofiber (CF) membrane greatly limit its further application in the oil–water separation process. To address this problem, polydopamine (PDA) was coated on the surface of CF via dip-coating method, playing a role of chelation and reduction in the process of electroless plating, so as to deposit copper nanoparticles on the surface of nanofiber. Subsequently, 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane was used for fluorination treatment to successfully obtain superhydrophobic electrospun carbon nanofiber (F/Cu/PDA/CF) membrane. The results show that F/Cu/PDA/CF membrane has good water contact angle (WCA, 158.5°) and excellent separation performance. The separation efficiency of oil–water mixture and emulsion is greater than 99.4%. Furthermore, the F/Cu/PDA/CF membrane demonstrates good environmental stability under different conditions (high/low temperature, UV irradiation, and immersion in organic solvents). These results indicate that superhydrophobic F/Cu/PDA/CF membrane has great application potential in the treatment of oily wastewater. [ABSTRACT FROM AUTHOR]

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.