Superhydrophobic Characteristics Research Articles

Superhydrophobicity wood with reversible photoresponsive property

Superhydrophobic photoresponsive wood (HPW) was synthesized through the vacuum pressure impregnation process with octadecyltrimethoxysilane (OTS), spiropyran, and polyvinyl alcohol (PVA). The process endowed the wood with photostimulation responsiveness and superhydrophobic characteristics. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS), Fourier transform infrared spectroscopy (FTIR), and a contact angle meter were analyzed to determine the micromorphology, chemical composition, and hydrophobicity of the modified wood. The modified wood had a micro-nanometer mastoid structure at the microscopic level, with a large number of hydrophobic groups. The static water contact angle of the modified wood reached 153°, the water absorption rate decreased from 123.28 % to 19.29 %, and the anti-swelling rate was only 1.69 %, showing good hydrophobic and anti-swelling performance. At the same time, color values of the wood L*, a*, b*, and total color difference ΔE*, it was found that spiropyran made the modified wood have a rapid response to light stimulation.

Robust, Flexible, and Superhydrophobic Fabrics for High-efficiency and Ultrawide-Band Microwave Absorption

Microwave absorption (MA) materials are essential for protecting against harmful electromagnetic radiation. In this study, highly efficient and ultrawide-band microwave-absorbing fabrics with superhydrophobic surface features were developed using a facile dip-coating method involving in situ graphene oxide (GO) reduction, deposition of TiO2 nanoparticles, and subsequent coating of a mixture of polydimethylsiloxane (PDMS) and octadecylamine (ODA) on polyester fabrics. Owing to the presence of hierarchically structured surfaces and low-surface-energy materials, the resultant reduced graphene oxide (rGO)/TiO2-ODA/PDMS-coated fabrics demonstrate superhydrophobicity with a water contact angle of 159° and sliding angle of 5°. Under the synergistic effects of conduction loss, interface polarization loss, and surface roughness topography, the optimized fabrics show excellent microwave absorbing performances with a minimum reflection loss (RLmin) of −47.4 dB and a maximum effective absorption bandwidth (EABmax) of 7.7 GHz at a small rGO loading of 6.9 wt%. In addition, the rGO/TiO2-ODA/PDMS coating was robust, and the coated fabrics could withstand repeated washing, soiling, long-term ultraviolet irradiation, and chemical attacks without losing their superhydrophobicity and MA properties. Moreover, the coating imparts self-healing properties to the fabrics. This study provides a promising and effective route for the development of robust and flexible materials with microwave-absorbing properties.

Study on superhydrophobicity and excellent corrosion resistance of a novel Ni‐SiC nanocomposite coating

AbstractCarbon steel is widely used, but it is prone to corrosion, which can lead to safety accidents. In this study, a novel Ni‐SiC coating was synthesized on the surface of carbon steel using a one‐step electrodeposition method, and the influence of electrodeposition parameters on the wettability of the coating was investigated. This coating possesses abundant micro‐nanostructures on its surface, which, after being placed in a vacuum drying environment for 2 weeks, endows it with superhydrophobic characteristics. Due to its superhydrophobic properties and the rich micro‐nanostructures, the corrosion current density of this coating is 1/18.95 that of bare steel. After immersion in a corrosive medium for some time, the polarization resistance value of the coated sample was observed to be 13.05 times greater than that of bare steel, demonstrating its remarkable ability to enhance the corrosion resistance of the surface. The results of this study can provide a reference for the anticorrosion work on carbon steel.

Experimental and theoretical study of hierarchical NiCo-TiO2 nanocomposite superhydrophobic surface for improving corrosion resistance

The superhydrophobicity of surfaces is a critical characteristic to prevent the corrosion problem, as a significant challenge under corrosive environments. In the present study, the nickel-cobalt (NC) alloy micro-nano hierarchical structure, along with the insertion of TiO2 nanoparticles (NCT) prepared by the economical and facile electrodeposition and myristic acid (MA) fatty acid physically adsorbed on the surface of NCT to reduce surface energy. The stability improvement of the prepared micro-nano scale composite due to the presence of TiO2 nanoparticles preserves the superhydrophobic feature created by the hierarchical structure and the fatty acid placed on the surface. The surface morphology and roughness, and the crystal structure of electrochemical deposited films were investigated using FE-SEM, AFM and XRD techniques, respectively. Also, mechanical and chemical stability, wetting behavior, and anti-corrosion properties were evaluated. The contact angle of 153° for the optimized Christmas tree-like nanocomposite (MA/NCT-2) implies the superhydrophobic property of the prepared coating. The excellent stability of MA/NCT-2 under corrosive different conditions, along with its supreme corrosion resistance confirm the potential of MA/NCT-2 for corrosion protection. Moreover, molecular dynamic (MD) simulations were performed in this first trial to determine wettability, intrinsic propagation mechanism, and structural evolution of water nanodroplets on copper (Cu) substrate and various coatings. The pristine substrate and NCT coating electrodeposited on the surface of Cu (NCT@Cu) were used to model the composite surfaces coated with MA. The last part concerned the study of the contact of this protective material with those surfaces and its possible improved performance as a superhydrophobic coating.

Bionic Nanocoating of Prosthetic Grafts Significantly Reduces Bacterial Growth.

Prosthetic materials are a source of bacterial infections, with significant morbidity and mortality. Utilizing the bionic "Lotus effect," we generated superhydrophobic vascular prostheses by nanocoating and investigated their resistance to bacterial colonization. Nanoparticles were generated from silicon dioxide (SiO2), and coated vascular prostheses developed a nanoscale roughness with superhydrophobic characteristics. Coated grafts and untreated controls were incubated with different bacterial solutions including heparinized blood under mechanical stress and during artificial perfusion and were analyzed. Bioviability- and toxicity analyses of SiO2 nanoparticles were performed. Diameters of SiO2 nanoparticles ranged between 20 and 180 nm. Coated prostheses showed a water contact angle of > 150° (mean 154 ± 3°) and a mean water roll-off angle of 9° ± 2°. Toxicity and viability experiments demonstrated no toxic effects of SiO2 nanoparticles on human induced pluripotent stem cell-derived cardiomyocytes endothelial cells, fibroblasts, and HEK239T cells. After artificial perfusion with a bacterial solution (Luciferase+ Escherichia coli), bioluminescence imaging measurements showed a significant reduction of bacterial colonization of superhydrophobic material-coated prostheses compared to that of untreated controls. At the final measurement (t = 60 min), a 97% reduction of bacterial colonization was observed with superhydrophobic material-coated prostheses. Superhydrophobic vascular prostheses tremendously reduced bacterial growth. During artificial perfusion, the protective superhydrophobic effects of the vascular grafts could be confirmed using bioluminescence imaging.

Nature-inspired parylene/SiO2 core-shell micro-nano pillars: Effect of topography and surface chemistry

We investigated the synergy of surface topography and chemistry in micro/nanostructured pillars inspired by nature, specifically mimicking tokay gecko (Gekko gecko Linnaeus, 1758) feet and sacred lotus (Nelumbo nucifera Gaertn., 1788) leaves. The aim is to understand and replicate their adhesive and self-cleaning properties for diverse applications. Through a detailed fabrication process and chemical modifications, the surfaces exhibit superhydrophobic characteristics. The research precisely examines the fabrication of surfaces with well-defined micropillars using lithography and deep silicon substrate etching. Diverse surface treatments, including silanization and O2 plasma, are applied to tailor the chemical composition of microstructured surfaces. Utilizing a ≈ 5 nm thin SiO2 interface layer, the study reveals superhydrophobic properties post-silanization and an eightfold increase in adhesion force (FA) between the studied surface and reference surfaces. FA measurements using atomic force microscopy reveal an eightfold increase in adhesion on both flat and microstructured surfaces, emphasizing the transformative effects of microstructures on surface morphology. The findings highlight the potential for multifunctional surface designs, elucidating that superhydrophobic properties correlate with structure topography while FA amplitude is predominantly determined by surface termination. Inspired by nature, this research unveils novel possibilities in functional materials and surface engineering, with broad implications across various applications.

Hydrophobic Surface Array Structure Based on Laser-Induced Graphene for Deicing and Anti-Icing Applications.

The exceptional performance of graphene has driven the advancement of its preparation techniques and applications. Laser-induced graphene (LIG), as a novel graphene preparation technique, has been applied in various fields. Graphene periodic structures created by the LIG technique exhibit superhydrophobic characteristics and can be used for deicing and anti-icing applications, which are significantly influenced by the laser parameters. The laser surface treatment process was simulated by a finite element software analysis (COMSOL Multiphysics) to optimize the scanning parameter range, and the linear array surface structure was subsequently fabricated by the LIG technique. The generation of graphene was confirmed by Raman spectroscopy and energy-dispersive X-ray spectroscopy. The periodic linear array structure was observed by scanning electron microscopy (SEM) and confocal laser imaging (CLSM). In addition, CLSM testings, contact angle measurements, and delayed icing experiments were systematically performed to investigate the effect of scanning speed on surface hydrophobicity. The results show that high-quality and uniform graphene can be achieved using the laser scanning speed of 125 mm/s. The periodic linear array structures can obviously increase the contact angle and suppress delayed icing. Furthermore, these structures have the enhanced ability of the electric heating deicing, which can reach 100 °C and 240 °C within 15 s and within 60 s under the DC voltage power supply ranging from 3 to 7 V, respectively. These results indicate that the LIG technique can be developed to provide an efficient, economical, and convenient approach for preparing graphene and that the hydrophobic surface array structure based on LIG has considerable potential for deicing and anti-icing applications.

Novel Ultra-High-Performance Concrete (UHPC) Enhanced by Superhydrophobic and Self-Luminescent Features

This study explores the potential of using basalt reinforced UHPC by incorporating simultaneously self-cleaning and self-luminescent features, paving the way for sustainable advancements in civil engineering. New green formulations of UHPC were developed by integrating supplementary cementitious materials and optimizing water to the binder ratio, followed by using basalt fibers to enhance strength and ductility. The fabricated samples with high particle-packing density exhibit sufficient workability and compressive strength up to 136 MPa, and, when incorporating basalt fibers, a notable reduction in brittleness. The inner microstructure of basalt fibers was observed to be smooth, homogeneously distributed, and well adhered to the UHPC matrix. To ensure the desired long-lasting visual appearance of decorative UHPC and reduce future maintenance costs, a time-effective strategy for creating a light-emitting biomimetic surface design was introduced. The samples exhibit high surface roughness, characterized by micro to nano-scale voids, displaying superhydrophobicity with contact angles reaching up to 155.45°. This is accompanied by roll-off angles decreasing to 7.1°, highlighting their self-cleaning features. The self-luminescence feature showcased intense initial light emission, offering a potential energy-efficient nighttime lighting solution.

Functionalized borosilicate-silica-epoxy nanocomposite superhydrophobic coating for corrosion inhibition under harsh environment

Current work proposes a facile scheme for fabrication of robust superhydrophobic borosilicate-silica-epoxy nanocomposite coatings on steel substrate with hierarchical structures, capable of inhibiting corrosion under harsh environment. The scheme amalgamates the advantageous properties of three ingredients: acid resistant property of borosilicate glass, superhydrophobic features of functionalized silica nanoparticles and durability of epoxy resin. The various steps of synthesis include 1. ball milling of borosilicate glass to micron and submicron size (~500 nm to 1.5 μm) 2. grafting of silica nanoparticles (~20 nm, through stober method) on the borosilicate particles to form rough hierarchical structure and 3. preparation of stable dispersion of the nanoparticles in epoxy-based resin followed by coating through immersion technique. Efficacy of the scheme was established through morphological, durability and electrochemical impedance studies. The surface morphology revealed hierarchical structures of functionalized silica nanoparticles (size range 20–100 nm) grafted on micro-sized borosilicate particles, which sustained water droplets with contact angle as high as 164.5° ± 2°. Sandpaper abrasion test proved excellent durability retaining hydrophobicity up to 250 abrasion cycles. The prepared surface maintained notable interface stability under aggressive environment: 3 and 10 days under pH 1 and 13 respectively. The electrochemical study in 3.5 wt% NaCl aqueous solution showed significant decrease in corrosion current density of coated surface (0.3585 μA/cm2) compared to uncoated surface (43.918 μA/cm2) suggesting excellent corrosion resistance. The results highlight scope of using this robust coating for abrasive and harsh environment.

Cr-Co Oxide Coatings Resistant to Corrosion, Electrodeposited on 304 SS Using an Ethylene Glycol-Water Solvent

The electrochemical co-deposition of Cr-Co oxide coatings at room temperature on 304 stainless steel (SS) was studied using an electrolyte composed of a mixture of ethylene glycol (EG), hydrated metal chloride salts (MCln∙YH2O), and water as a secondary hydrogen donor (HBD). Metallic Cu and Ni undercoats were applied to improve the adhesion of a posterior Cr-Co metallic and oxide layer. The electroactive events that took place during both electrodeposition processes were studied using cyclic voltammetry (CV) and chronoamperometry. The microstructure and composition of the surface layers were studied using scanning electron microscopy (SEM/EDS), X-ray diffraction (XRD) and cross-sectional elemental mapping via transmission electron microscopy (TEM). The surface of steel with the Cr-Co:EG-H2O coating showed greater resistance to pitting corrosion (123.93 mV) compared to untreated stainless steel (62.3 mV). This sample showed a large hystere-sis area, which is associated with high resistance to pitting corrosion by the occurrence of a re-passivation of the sample at a Erep value of 24.31 mV. After the cyclic potentiodynamic polariza-tion (CPP) test, the lowest specific mass loss (0.001 mg/cm2) was achieved for the AISI 304 SS sample coated using EG-water solvents (Cr-Co:EG-H2O), while the untreated AISI 304 SS reached a higher specific mass loss (0.01 mg/cm2). The Electrochemical Impedance Spectroscopy (EIS) tests showed that the uniform corrosion resistance varied significantly from the untreated AISI 304 SS (35 kΩ) to the coated sample (57 kΩ), which is attributed to the protection provided by the chromium and cobalt oxides coating. The best corrosion resistance achieved was correlated with a superhydrophobic character (with a contact angle of 158.41°) of the Cr-Co coatings. This was in turn a consequence of a needle-like morphology characteristic of these oxides.

Digital light processing technique aided 3D printing hierarchical super-wetting mesh coated with hydrophobic SiO2 for highly efficient oil-water separation

Gravity-driven filtration using super-wetting mesh surfaces holds significant promise in addressing oil pollution resulting from human activities. However, conventional techniques need help fabricating efficient separation mesh structures due to their limited stability in oily-water solutions. To overcome this, we employed a Digital Light Processing (DLP) 3D printing technique to fabricate a mesh with a micro-patterned surface using a UV light-curable polyurethane (PU). A post-UV curing step was implemented to transform the soft segments of PU into a solid state. To enhance the super-wetting properties, hydrophobic modified silica (m-SiO2)/UV curable polydimethylsiloxane (PDMS) solution was applied through dip coating, resulting in a hierarchical structure with high surface roughness and superhydrophobic characteristics. In oil–water separation tests, the hierarchical superhydrophobic mesh, featuring a pore size of 300 µm, demonstrated exceptional performance, achieving a remarkable flow flux of 37,410 L/m2 h with a separation efficiency of 97.46 %. Furthermore, the separation efficiency remained consistently above 97.0 % under varying pH conditions and oil mixtures, highlighting the excellent water-repellence capacity of the hierarchical mesh developed in this study.

Superhydrophobic, mechanically durable, highly transparent surface covered with CuO/PDMS composite nano-tips using one-step wet oxidation process of Cu/PDMS multilayer

In this study, a mechanically durable, transparent, and superhydrophobic CuO/polydimethylsiloxane (PDMS) composite nano-tips surface was fabricated by a wet oxidation process of a Cu/PDMS multilayer structure. A growth mechanism for the CuO/PDMS composite nano-tips was proposed accounting for the superhydrophobic characteristics of the CuO/PDMS nanostructured surface: During wet oxidation, as CuO nanowires form and grow, the PDMS surface in contact with Cu is dragged up along the CuO nano-tips surface, eventually becoming a CuO/PDMS nanocomposite superhydrophobic surface. The fabricated CuO/PDMS nano-tips surface showed superhydrophobicity with a water contact angle of 158°, and optical transmittance of up to 93.8 % in the 400–700 nm wavelength range. Additionally, the mechanical durability of the fabricated surfaces was also investigated. Repeated touching force (∼1.0 kgf), stretching (∼100 %), and bending (∼100°) 1000-cycle test results confirm the mechanical durability of the CuO/PDMS nanostructured surface. As a mechanically durable, transparent, and superhydrophobic film, the CuO/PDMS nanostructured surface was used as protective film for a touch screen. This study offers novel insights into the durability of artificial superhydrophobic surfaces and the synthesis methods of metal oxide-polymer nanocomposites.

Mass Transport Impedance in a PEMFC with Superhydrophobic Catalyst Layers

Electrosprayed catalyst layers improve liquid water management in PEMFCs thanks to their superhydrophobic character [1]. Using appropriate parameters, the electrospray deposition of a suspension of Pt/C powder and ionomer (Nafion solution) gives rise to a macroporous layer with superhydrophobic pores. Under current generation in a PEMFC, superhydrophobicity of the cathodic catalyst layer minimizes water interaction with pores walls, and enhances water transport towards the anode. As a consequence, water distribution inside the cell is more homogeneous, which makes cathode flooding less severe and improves anode humidification. PEMFCs with cathodic electrosprayed catalyst layer have shown higher power production rate at intermediate and high current densities, with peak power densities above 20%-25% compared with conventional, more hydrophilic, catalyst layer under standard testing conditions. We have studied in previous works the transport properties of electrosprayed catalyst layers with a number of techniques, like polarization curves, electrochemical impedance spectroscopy, and hydrogen transport.In this communication, catalyst layer transport properties in a PEMFC with electrosprayed electrodes are studied with 'Current Modulated Hydrogen Flow Rate Spectroscopy' (CH2S) [2], which is a transport impedance technique relating hydrogen flow rate with faradaic current. With this aim, PEMFCs have been mounted with electrosprayed catalyts layers in anode and in cathode. When in anode, the electrosprayed catalyst layer gives rise to significant differences in the CH2S Nyquist plots and dependent on cell humidification (Fig. 1). The CH2S signals resolve transport kinetics having different characteristic times, that can be assigned to transport in different parts of the anode, like flow-field, gas diffusion layer, microporous layer and catalyst layer. The study is completed with CH2S measurements on PEMFCs with different configurations, having electrosprayed electrodes in anode and cathode. It is concluded that CH2S provides new insights into mass transport properties of gas diffusion electrodes.AcknowledgementsFunding by PORHYDRO2 project (TED2021-131620B-C22, ‘Preparation and characterisation of catalyst layers fabricated by electrospray for proton exchange fuel cells with passive gas feed’) by the Spanish Ministry of Science and Innovation.[1] M.A. Folgado, J.J. Conde, P. Ferreira-Aparicio, A.M. Chaparro, Single Cell Study of Water Transport in PEMFCs with Electrosprayed Catalyst Layers, Fuel Cells. 18 (2018) 602–612. https://doi.org/10.1002/fuce.201700217.[2] L. Duque, A. Molinero, J.C. Oller, J.M. Barcala, M.A. Folgado, A.M. Chaparro, Analysis of Hydrogen Feeding to the Anode of a PEMFC By a Transport Impedance Technique, ECS Meet. Abstr. MA2022-02 (2022) 1406–1406. https://doi.org/10.1149/ma2022-02391406mtgabs. Figure 1

Enhancement of anticorrosion resistance of a fluorinated polyimide matrix by incorporating self-fixing POSS-GO

In this study, we aimed to enhance the anticorrosion performance of composite coatings by introducing polyhedral oligomeric silsesquioxane (POSS)-grafted graphene oxide surfaces. These surfaces were modified to achieve super-hydrophobicity and a self-fixing effect. The modified material was employed to enhance the corrosion resistance of fluorinated polyimide (FPI) composite coatings composed of graphene oxide (GO) grafted by POSS (POSS-GO). The resulting composite coating exhibited substantially improved corrosion resistance compared to a pure FPI coating. The impedance modulus (|Z|0.01 Hz) of the 0.3 wt% FPI/POSS-GO coating was approximately 2.57 × 1011 Ω·cm2, which was greater than that of the pure FPI coating by approximately five orders of magnitude. The enhanced performance can be attributed to the synergistic interaction between the intrinsically hydrophobic polyimide matrix polymer, which acts as a barrier, and the POSS-GO fillers with their superhydrophobic and self-fixing characteristics. Notably, these properties remained effective even after subjecting the coatings to a 3.5 wt% NaCl solution during a 45-day salt spray test. These findings have significant implications for the development of cost-effective anticorrosion coatings for metal substrates.

CNTs-induced superhydrophobic and photothermal coating with long-term durability and self-replenishing property for anti-icing/de-icing

Ice formation and accumulation of various equipment often leads to economic loss and severe traffic accidents. Although numerous anti-icing coating strategies have been exploited in recent years, robust and durable surfaces for effective anti-icing and de-icing remains a big challenge. In this work, mesoporous silica nanoparticles (mSiO2) were loaded with high-dosage polydimethylsiloxane (PDMS) to prepare hydrophobic PDMS@mSiO2 aggregates, which was then incorporated into silicon resin matrix together with carbon nanotubes (CNTs), to construct a near infrared-responsive anti-icing/de-icing coating by a one-step spraying method. The PDMS@mSiO2 particles imparted to the coating micro-scaled roughness and low surface energy, and the CNTs supplemented the formation of micro-nano hierarchical structure to enhance the water repellency and offered the photothermal property. Consequently, the prepared coating possessed superhydrophobic character with the contact angle up to 154.3 ° as well as the delayed freezing time of 440 s at −20 °C, nearly 73 times of that on aluminum plates. Furthermore, the as-obtained coating exhibited robust adhesion and stable anti-icing properties under various harsh environmental conditions, which is promising for anti-icing and de-icing modification of rotor wings with robustness and long-term durability.

Multifunctional carbonized Zn-MOF coatings for cotton fabric: Unveiling synergistic effects of superhydrophobic, oil-water separation, self-cleaning, and UV protection features

This paper investigates the development of a multifunctional carbonized zinc (Zn)-based metal organic framework (MOF) coating on cotton fabric, aiming to reveal the synergistic effects of superhydrophobicity, oil-water separation, self-cleaning, and UV protecting properties. Cotton fabric was first coated by carbonized zinc oxide (ZnO) derived from MOF under nitrogen atmosphere and subsequently treated with hexadecyltrimethoxysilane (HDTMS). Various characterization analyses were employed to characterize the coated fabrics. The coated fabric exhibited significant superhydrophobic effects, displaying 160° static water contact angle with 7° hysteresis. Moreover, the final product demonstrated excellent efficiencies of 95, 98, 97, and 93 % in separating crude oil, chloroform, n-hexane, and engine oil from water, and 90 % for stabilized emulsion due to the large surface area and superhydrophobic properties. Also, the treated fabric showed reusability for viscose oil such as coconut oil and sunflower oil with nearly 100 % separation and stable recyclability up to 5 cycles. Furthermore, the coated fabric displayed outstanding resistance to photo-corrosion over a 2-year period under sunlight, showing remarkable photostability. The incorporation of ZnO derived MOF and HDTMS coating further enhanced the UV protection of the fabric. Overall, this study presents a comprehensive analysis of the multifunctional properties of carbonized Zn-MOF-coated cotton fabric, highlighting its potential for various applications including self-cleaning, UV protection, and water-oil separation.

A photothermal superhydrophobic coating with un-fluorinated modified CNTs for anti-icing applications on concrete

The problem of easy icing and difficult anti-icing on concrete pavement has prompted using superhydrophobic coatings as a potential solution. However, the coatings are prone to wetting failure after repeated icing-deicing cycles. In this study, a superhydrophobic and photothermal coating consisting of unfluorinated modified-carbon nanotubes (M-CNTs) and commercial epoxy is constructed by a simple spray process on concrete for anti-icing. Incorporating M-CNTs imparts the coating with exceptional superhydrophobic and photothermal characteristics, endowing the coating surface with excellent deicing under sunlight irradiation. The contact angle of the coating reaches 151° at −10 °C, and the freezing time extends from 55 s to 680 s. Under one sunlight intensity, the coating temperature rapidly increases from −10 ℃ to 81 ℃, and the ice changes from solid to liquid. It effectively acts as a barrier between water and the concrete surface, making it highly suitable and valuable in practical applications.

Up to Date Review of Nature-Inspired Superhydrophobic Textiles: Fabrication and Applications

In recent years, with the rapid development of the economy and great progress in science and technology, people have become increasingly concerned about their quality of life and physical health. In order to pursue a higher life, various functional and biomimetic textiles have emerged one after another and have been sought after by people. There are many animal and plant surfaces with special wettability in nature, and their unique “micro-nano structures” and low surface energy have attracted extensive attention from researchers. Researchers have prepared various textiles with superhydrophobic features by mimicking these unique structures. This review introduces the typical organisms with superhydrophobicity in nature, using lotus, water strider, and cicada as examples, and describes their morphological features and excellent superhydrophobicity. The theoretical model, commonly used raw materials, and modification technology of superhydrophobic surfaces are analyzed. In addition, the application areas and the current study status of superhydrophobic surfaces for textiles are also summarized. Finally, the development prospects for superhydrophobic textiles based on bionic technology are discussed.

Phyllostachys Viridis-Leaf-like MLMN Surfaces Constructed by Nanosecond Laser Hybridization for Superhydrophobic Antifogging and Anti-Icing.

In nature, many species commonly evolve specific functional surfaces to withstand harsh external environments. In particular, structured wettability of surfaces has attracted tremendous interest due to its great potential in antifogging and anti-icing properties. Phyllostachys Viridis is a resistant low-temperature (-18 °C) plant with superhydrophobicity and ice resistivity behaviors. In this work, with inspiration from the representative cold-tolerant plants leaves, a unique multilevel micronano (MLMN) surface was fabricated on copper substrate by ultrafast laser process, which exhibited superior superhydrophobic characteristics with the water contact angle > 165° and rolling angle< 2°. In the dynamic wettability experiment, the rebound efficiency of the droplet on the MLMN surface reached 20.6%, and the contact time was only 10.6 ms. In the condensation experiment, the nucleation, growth, merging, and bouncing of fog drops on the surface was distinctly observed, indicating that rational texture structures can improve the antifogging performance of the surface. In the anti-icing experiment, the freezing time was delayed to 921 s at -10 °C, and the freezing time of salt water reached a staggering 1214 s. Moreover, the mechanical durability of MLMN surfaces was confirmed by scratch damage, sandpaper abrasion, and icing and melting cycle tests, and their repairability was evaluated for product applications in practice. Finally, the underlying antifogging/anti-icing strategy of the MLMN surface was also revealed. We anticipate that the investigations offer a promising way to handily design and fabricate multiscale hierarchical structures with reliable antifogging and anti-icing performance, especially in saltwater-related applications.

Cotton Cloth@ Polydimethylsiloxane -Graphene Flakes- Titanium Dioxide Composite Membrane for Wastewater Purification

Interfacial solar steam generation (ISSG) has been regarded as a simple and highly-efficient method for wastewater purification. Herein, we prepared a superhydrophobic composite membrane, in which polydimethylsiloxane employed as binders to pack graphite flakes and titanium dioxide tightly onto cotton cloth (defined as cotton cloth@PDMS-C-P25). Benefiting from its powerful photothermal effects, cotton cloth@PDMS-C-P25 exhibited high evaporation flux of 1.86 kg m−2 h−1 and 1.73 kg m−2 h−1 for pure water and seawater, respectively. Meanwhile, the prepared composite membrane fulfilled the targets of sewage purification set by its photocatalytic properties, which demonstrated a degradation rate of 66.1 % for Rhodamine B (RhB), and antibacterial efficiency of over 99.99 % for Escherichia coli (E. coli). Furthermore, cotton cloth@PDMS-C-P25 surface was endowed with superhydrophobic and low-adhesion characteristics mainly owing to the synergy of multiscale structure and low surface energy matter, which contribute to the anti-adhesion effect of 97.9 % for E. coli at a high concentration of 107 colony forming units (CFUs). In this work, the cost-effective, environmentally friendly, long-term stable, and superhydrophobic solar-absorber holds a potential prospect for wastewater treatment and desalination in a typical pollution-induced water shortage area.