Search Results (184)

The superhydrophobic coatings for outdoor use need to be exposed to sunlight for a long time; therefore, their UV-aging resistances are crucial in practical applications. In this study, the primary product of titanium dioxide (P-TiO₂) was used as the raw material. Nano-silica (SiO₂) was coated onto the surface of P-TiO₂ by the acid precipitation method to prepare P-TiO₂-SiO₂ composite particles. Then, they were modified and sprayed simply to obtain a superhydrophobic P-TiO₂-SiO₂/HDTMS coating. The results indicated that amorphous nano-SiO₂ was coated on the P-TiO₂ surface, forming a micro–nano binary structure, which was the essential structure to form superhydrophobic coatings. Additionally, the UV-aging property of P-TiO₂ was significantly enhanced after being coated with SiO₂. After continuous UV irradiation for 30 days, the color difference (ΔE*) and yellowing index (Δb*) values of the coating prepared with P-TiO₂-SiO₂ increased from 0 to 0.75 and 0.23, respectively. In contrast, the ΔE* and Δb* of the coating prepared with P-TiO₂ increased from 0 to 1.68 and 0.74, respectively. It was clear that the yellowing degree of the P-TiO₂-SiO₂ coating was lower than that of P-TiO₂, and its UV-aging resistance was significantly improved. After modification with HDTMS, the P-TiO₂-SiO₂ coating formed a superhydrophobic P-TiO₂-SiO₂/HDTMS coating. The water contact angle (WCA) and water slide angle (WSA) on the surface of the coating were 154.9° and 1.3°, respectively. Furthermore, the coating demonstrated excellent UV-aging resistance. After continuous UV irradiation for 45 days, the WCA on the coating surface remained above 150°. Under the same conditions, the WCAs of the P-TiO₂/HDTMS coating decreased from more than 150° to 15.3°. This indicated that the retention of surface hydrophobicity of the P-TiO₂-SiO₂/HDTMS coating was longer than that of P-TiO₂/HDTMS, and the P-TiO₂-SiO₂/HDTMS coating’s UV-aging resistance was greater. The superhydrophobic P-TiO₂-SiO₂/HDTMS self-cleaning coating reported in this study exhibited outstanding UV-aging resistance, and it had the potential for long-term outdoor use. Full article

As an emerging energy-saving approach, bio-inspired drag reduction technology has become a key research direction for reducing energy consumption and greenhouse gas emissions. This study introduces the latest research progress on bio-inspired microstructured surfaces in the field of underwater drag reduction, focusing on analyzing the drag reduction mechanism, preparation process, and application effect of the three major technological paths; namely, bio-inspired non-smooth surfaces, bio-inspired superhydrophobic surfaces, and bio-inspired modified coatings. Bio-inspired non-smooth surfaces can significantly reduce the wall shear stress by regulating the flow characteristics of the turbulent boundary layer through microstructure design. Bio-inspired superhydrophobic surfaces form stable gas–liquid interfaces through the construction of micro-nanostructures and reduce frictional resistance by utilizing the slip boundary effect. Bio-inspired modified coatings, on the other hand, realize the synergistic function of drag reduction and antifouling through targeted chemical modification of materials and design of micro-nanostructures. Although these technologies have made significant progress in drag reduction performance, their engineering applications still face bottlenecks such as manufacturing process complexity, gas layer stability, and durability. Future research should focus on the analysis of drag reduction mechanisms and optimization of material properties under multi-physical field coupling conditions, the development of efficient and low-cost manufacturing processes, and the enhancement of surface stability and adaptability through dynamic self-healing coatings and smart response materials. It is hoped that the latest research status of bio-inspired drag reduction technology reviewed in this study provides a theoretical basis and technical reference for the sustainable development and energy-saving design of ships and underwater vehicles. Full article

A superhydrophobic surface with hierarchical micro/nano-array structures was successfully fabricated on 6061 aluminum alloy through a combination of femtosecond laser etching and anodic oxidation. Femtosecond laser etching formed a regularly arranged microscale “pit-protrusion” array on the aluminum alloy surface. After modification with a fluorosilane ethanol solution, the surface exhibited superhydrophobicity with a contact angle of 154°. Subsequently, the anodic oxidation process formed an anodic oxide film dominated by an array of aluminum oxide (Al₂O₃) nanopores at the submicron scale. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed that the nanopore structures uniformly and continuously covered the laser-ablated layer. This hierarchical structure significantly increased the surface water contact angle to 162°. Wettability analysis showed that the prepared composite coating formed an air layer accounting for 91% of the surface area. Compared with the sample only treated by femtosecond laser etching, the presence of the Al₂O₃ nanopore structure significantly enhanced the mechanical durability, superhydrophobic durability, and corrosion resistance of the superhydrophobic surface. The proposed multi-step fabrication strategy offers an innovative method for creating multifunctional, durable superhydrophobic coatings and has important implications for their large-scale industrial use. Full article

To address the challenges of cotton cellulose materials being susceptible to environmental humidity and pollutant erosion, a strategy for constructing superhydrophobic functional coatings with biomimetic micro–nano composite structures was proposed. Through surface silanization modification, diatomite (DEM) and Fe₃O₄ nanoparticles were functionalized with octyltriethoxysilane (OTS) to prepare superhydrophobic diatomite flakes (ODEM) and OFe₃O₄ nanoparticles. Following the multi-scale composite principle, ODEM and OFe₃O₄ nanoparticles were blended and crosslinked via the hydroxyl-initiated ring-opening polymerization of epoxy resin (EP), resulting in an EP/ODEM@OFe₃O₄ composite coating with hierarchical roughness. Microstructural characterization revealed that the micrometer-scale porous structure of ODEM and the nanoscale protrusions of OFe₃O₄ form a hierarchical micro–nano topography. The special topography combined with the low surface energy property leads to a contact angle of 158°. Additionally, the narrow bandgap semiconductor characteristic of OFe₃O₄ induces the localized surface plasmon resonance effect. This enables the coating to attain 80% light absorption across the 350–2500 nm spectrum, and rapidly heat to 45.8 °C within 60 s under 0.5 sun, thereby demonstrating excellent deicing performance. This work provides a theoretical foundation for developing environmentally tolerant superhydrophobic photothermal coatings, which exhibit significant application potential in the field of anti-icing and anti-fouling. Full article

Graphene oxide (GO) films have attracted significant attention due to their potential in separation and filtration applications. Based on their unique lamellar structure and ultrathin nature, GO films are difficult to maintain in a free-standing form and typically require substrate support. Consequently, understanding their film formation behavior and mechanisms on substrates is of paramount importance. This work employs commonly used nonwoven fibrous membranes as substrates and guided by the coffee-ring theory, systematically investigates the film formation behaviors, film morphology, and underlying mechanisms of GO films on fibrous membranes with varying wettability. Fibrous membranes with different wetting properties—hydrophilic, hydrophobic, and superhydrophobic—were prepared via electrospinning and initiated chemical vapor deposition (iCVD) surface modification techniques. The spreading behaviors, deposition dynamics, capillary effects, and evaporation-induced film formation mechanisms of GO suspensions on these substrates were thoroughly examined. The results showed that GO formed belt-like, ring-like, and circular patterns on the three fibrous membranes, respectively. GO films encapsulated more than the upper half, approximately the upper half, and the top portion of fibers, respectively. Pronounced wrinkling of GO films was observed except for those on the hydrophilic fibrous membrane. This work demonstrates that tuning the wettability of fibrous substrates enables precise control over GO film morphology, including fiber encapsulation, wrinkling, and coverage area. Furthermore, it deepens the understanding of the interactions between 1D nanofibers and 2D GO sheets at low-dimensional scales, laying a foundational basis for the optimized design of membrane engineering. Full article

Natural surfaces, such as lotus leaves, springtail cuticles, and pitcher plant peristomes, exhibit extraordinary wetting behaviors due to their unique surface topographies and chemical compositions. These natural architectures have inspired the development of wettability models and the production of artificial surfaces with tailored wettability for advanced applications. Electrodeposited metallic coatings can imitate the wettability behaviors of natural surfaces, showing superhydrophobic, superoleophobic, or slippery characteristics. Such coatings can significantly enhance corrosion resistance by minimizing water–metal contact and promoting self-cleaning effects. This review presents various strategies for fabricating corrosion-resistant metallic coatings, including different electrodeposition techniques in aqueous or non-aqueous baths, followed by post-treatment procedures and surface functionalization methods. However, despite the promising protective properties demonstrated under controlled laboratory conditions, long-term studies under natural exposure conditions are still lacking, which limits the full assessment of the durability and effectiveness of non-wettable electroplated deposits in practical applications. Full article

Research on bionic superhydrophobic surfaces draws inspiration from the microstructures and wetting mechanisms of natural organisms such as lotus leaves, water striders, and butterfly wings, offering innovative approaches for developing artificial functional surfaces. By synergistically combining micro/nano hierarchical structures with low surface energy chemical modifications, researchers have devised various fabrication strategies—including laser etching, sol-gel processes, electrochemical deposition, and molecular self-assembly—to achieve superhydrophobic surfaces characterized by contact angles exceeding 150° and sliding angles below 5°. These technologies have found widespread applications in self-cleaning architectural coatings, efficient oil–water separation membranes, anti-icing materials for aviation, and anti-biofouling medical devices. This article begins by examining natural organisms exhibiting superhydrophobic properties, elucidating the principles underlying their surface structures and the wetting states of droplets on solid surfaces. Subsequently, it categorizes and highlights key fabrication methods and application domains of superhydrophobic surfaces, providing an in-depth and comprehensive discussion. Full article

The inherent flammability and hydrophilicity of nylon/cotton (NC) blend fabrics limit their practical applications. Traditional hydrophobic treatments often involve fluorinated compounds or nanomaterials, which raise environmental concerns and exhibit poor durability. To address these issues, this study developed a sustainable multifunctional finishing strategy. Initially, the nylon/cotton blended fabric was pretreated with 3-glycidyloxypropyltrimethoxy silane (GPTMS). An intumescent flame retardant coating based on bio-derived phytic acid (PA) and polyethyleneimine (PEI) was constructed on NC fabrics via a layer-by-layer (LBL) self-assembly process. Subsequently, polydimethylsiloxane (PDMS) was grafted to reduce surface energy, imparting synergistic flame retardancy and superhydrophobicity. The treated fabric (C-3) showed excellent flame retardant and self-extinguishing behavior, with no afterflame or afterglow during vertical burning and a char length of only 35 mm. Thermogravimetric analysis revealed a residual char rate of 43.9%, far exceeding that of untreated fabric (8.6%). After PDMS modification, the fabric reached a water contact angle of 157.8°, indicating superior superhydrophobic and self-cleaning properties. Durability tests showed that the fabric maintained its flame retardancy (no afterflame or afterglow) and superhydrophobicity (WCA > 150°) after 360 cm of abrasion and five laundering cycles. This fluorine-free, nanoparticle-free, and environmentally friendly approach offers a promising route for developing multifunctional NC fabrics for applications in firefighting clothing and self-cleaning textiles. Full article

Since 2015, research on liquid–solid triboelectric nanogenerators (L-S TENGs) has shown steady growth, with the primary focus on application domains such as engineering, physics, materials science, and chemistry. These applications have underscored the significant attention L-S TENGs have garnered in areas like human–nature interaction, energy harvesting, data sensing, and enhancing living conditions. Presently, doping composite dielectric materials and surface modification techniques are the predominant methods for improving the power generation capacity of TENGs, particularly L-S TENGs. However, studies exploring the combined effects of these two approaches to enhance the power generation capacity of TENGs remain relatively scarce. Following a review of existing literature on the use of composite material doping and surface modification to improve the power generation performance of L-S TENGs, this paper proposes an experimental framework termed “self-assembled surface TENG@carbonyl iron particle doping (SAS-TENG@CIP)” to investigate the integrated power generation effects of L-S TENGs when combining these two methods. Research cases and data results indicate that, for TENGs exhibiting capacitor-like properties, the enhancement of power generation performance through composite material doping and superhydrophobic surface modification is not limitless. Each process possesses its own inherent threshold. When these thresholds are surpassed, the percolation of current induced by material doping and electrostatic breakdown (EB) triggered by surface modification can lead to a notable decline in the power output capacity of L-S TENGs. Consequently, in practical applications moving forward, fully realizing the synergistic potential of these methods necessitates a profound understanding of the underlying scientific mechanisms. The conclusions and insights presented in this paper may facilitate their complex integration and contribute to enhancing power generation efficiency in future research. Full article

This study presents the synthesis, characterization, and evaluation of stearic-acid-coated sand (SACS) as a superhydrophobic material for agricultural water management applications. The fabrication process involves coating silica sand particles with stearic acid in an ethanol-based solution, followed by controlled drying to achieve a stable and uniform hydrophobic layer. Structural, chemical, and physical characterizations confirmed the successful functionalization of the sand surface. The coated sand exhibited a high water contact angle (WCA > 150°), indicating strong water repellency and potential for reducing water loss in soil systems. Experimental results demonstrated enhanced moisture retention in SACS-treated soil, prolonging water availability by up to four additional days compared to untreated samples. Despite its promising performance, potential degradation under acidic or organic solvent exposure remains a concern for long-term application. Overall, this work presents SACS as a low-cost, scalable solution to improve water conservation in dry agricultural areas, supporting sustainable farming practices. Full article

Laser surface texturing (LST) is a versatile method for enhancing material surface properties, offering high precision and flexibility for surface modification. This review comprehensively examines the application of laser texturing technology for surface protection and functional regulation of aluminum alloys, focusing on wettability, anti-icing, corrosion resistance, and wear resistance. It highlights recent progress in laser surface patterning techniques, describing the principles and attributes of methods such as direct laser writing, laser interference patterning, and laser shock treatment. The influence of laser intensity, scanning velocity, and texture spacing on surface topography is discussed thoroughly. Mechanisms of wettability control via laser surface texturing are summarized, emphasizing the key factors required to achieve superhydrophobic or hydrophilic properties through texture design. Advancements in enhancing anti-icing, anti-frost, anti-fouling, and anti-corrosion properties through multi-scale textures and their synergistic effects with functional coatings are analyzed. Additionally, the enhancement of wear resistance and friction performance under both dry and lubricated conditions is reviewed, with a focus on how the geometry and arrangement of textures affect the coefficient of friction and wear rate. Finally, the paper addresses challenges and future directions, including process optimization, scalability, and the integration of LST with advanced coatings to maximize its potential in aluminum alloy applications. Full article

The preparation of superhydrophobic functional materials is of great significance for applications in oil pollution control. However, the materials synthesized by traditional post-modification methods usually suffer from problems of limited active sites, uneven distribution, and susceptibility of the surface structure to external factors, which may significantly affect their superhydrophobic properties. In this study, the superhydrophobic porous organic polymer LNU-32 was successfully prepared via in situ polymerization with the introduction of green, low-surface-energy, long-alkyl-chain functional groups into the pores, which formed a “brush-like” structure on the pore surface of the polymer and effectively enhanced its hydrophobicity. The LNU-32 material exhibits excellent superhydrophobicity, with a water contact angle of more than 151°. In addition, the superhydrophobic polyester fabric prepared from LNU-32 has an oil–water separation efficiency of more than 90%. The adsorption capacity of the superhydrophobic fabric for dimethicone also reached 7.37 times its own weight. The study shows that the LNU-32 material exhibits good application potential in the field of oil–water separation, especially in the treatment of oily wastewater and oil spills. Full article

Superhydrophobic metal wires have shown great application prospects in oil–water separation, anti-corrosion, anti-icing, and other fields due to their excellent water repellency. However, how to fabricate a superhydrophobic surface on ultra-fine metal wire remains a challenge. Here, we proposed a method using laser processing to efficiently fabricate superhydrophobic ultra-fine brass wire. Firstly, we analyzed the mechanism of the laser processing of curved surfaces and designed a controllable angle rotation fixture to avoid the machining error caused by secondary positioning in the machining process. Then, we investigated the influences of the laser power, scanning speed, and scanning times on the surface morphology and wettability of the ultra-fine brass wire. The optimal laser processing parameters were obtained: laser power of 6 W, scanning speed of 500 mm/s, and scanning time of 1. After low surface energy modification, the water contact angle and surface roughness Sa of the ultra-fine brass wire were 156° and 1.107 μm, respectively. This work is expected to enrich the theory and technology for fabricating superhydrophobic ultra-fine brass wire. Full article

Oil–water separation is an important method for treating oily wastewater and recovering oil resources. Based on the different affinities of superhydrophobic surfaces to water and oil, long-term oil–water separation devices with low-energy and high efficiency can be developed through the optimization of structure and process parameters. Superhydrophobic coatings were prepared on stainless-steel mesh surfaces using a spray method to construct single-channel oil–water separation equipment with superhydrophobic/oleophilic meshes, and the effects of structural and process parameters on separation efficiency were systematically investigated. Additionally, a multi-channel oil–water separation device was designed and fabricated to evaluate the feasibility and stability of long-term continuous operations. The optimized single V-shaped channel should be horizontally placed and made from 150-mesh stainless-steel mesh folded at an angle of 38.9°. For the oil–water mixtures containing 20 wt.% oil, the oil–water separation efficiencies for single and two-stage separation were 92.79% and 98.96%, respectively. After 36 h of continuous operation, the multi-channel separation device achieved single-stage and two-stage separation efficiencies of 94.60% and 98.76%, respectively. The maximum processing capacity of the multi-channel device reached 168 L/h. The modified stainless mesh can remain stable with a contact angle (CA) higher than 150° to water for 34 days. The average residence time and contact area during the oil–water separation process significantly affect separation efficiency. By optimizing oil–water separation structures and process parameters, and using a superhydrophobic spray modification method, separation efficiency can be improved while avoiding the generation of secondary pollutants. Full article

Wood serves as a green biomass material with sustainable utilization and environmental friendliness. The modification of wood can be used to obtain superhydrophobic properties and further expand wood’s application range. This paper focuses on the development status of superhydrophobic surfaces with micro-/nanoscale rough structures. Based on the surface wettability theory, this paper introduces common methods of superhydrophobic modification of wood materials, compares the advantages and disadvantages of these methods, discusses the relationship between the surface microstructure and wettability, and summarizes the applications of superhydrophobic wood in oil–water separation, self-cleaning, and self-healing. Finally, the future development strategies of superhydrophobic coating materials are elucidated to provide basic theoretical support for the synthesis and diverse applications of superhydrophobic wood and a reference for subsequent research and development. Full article