Superhydrophobic Research Articles

Fluorine-Free Multi-durable Superhydrophobic Cotton Fabrics Prepared by an Atomization Spraying Method for Self-Cleaning and Oil-Water Separation.

Superhydrophobic textiles have special applications in many fields such as medical treatment, military protection, oil-water separation, etc. In the large-scale pad-dry-cure process, a large number of polymer binders are often added to improve the superhydrophobic durability, resulting in a significant reduction in air permeability. To address this issue, a low-liquid atomization spray method was adopted to fabricate multi-durable superhydrophobic cotton fabrics using N1,N6-bis(2,3-epoxypropyl)hexane-1,6-diamine, a silica precursor, and fluorine-free hexadecyltrimethoxysilane as the main modifiers. The prepared fabric maintained excellent water repellency even after being subjected various harsh conditions tests such as 2000 cycles of friction, 40 washing cycles, ultrasonic treatment for 120 min, 200 tape peelings, and acid-alkali-salt corrosion for 24 h. The air permeability of the superhydrophobic fabric was measured to be 370.2 L m-2 s-1, which was merely 5% lower than that of the original fabric, indicating that the modified fabric retains satisfactory air permeability. The modified fabric exhibited an excellent self-cleaning effect with respect to various liquids. In addition, the prepared fabric showed good oil-water separation capability for both heavy and light oils. For heavy oil-water mixtures, the fabric sample exhibited a maintenance of 98.13% separation efficiency and a high flux of 18 032 L m-2 h-1 after 10 uses. These findings will help to promote the practical application of low-feed interface modification technology in the production of durable functional textiles.

Construction of a self-floating fabric based on CVD-assisted coating and its application in interfacial evaporation

The discharge of industrial wastewater and the shortage of fresh water resources are increasingly endangering human daily life. In this experiment, bismuth oxychloride with oxygen vacancies was attached to a fabric surface using the solution deposition method, and then perfluoro-trichlorosilane was grafted on the surface to prepare a multifunctional superhydrophobic fabric. After mechanical stability testing, the fabric retained a water contact angle that consistently exceeded 150°, which could realize the selective adsorption of insoluble oil such as cyclohexane. Through a capture experiment of active species, the conclusion drawn was that holes (h+) and superoxide free radicals (·O2−) were primary active species for the photocatalytic degradation process. After 4 cycles of photodegradation, the degradation efficiency could still reach 92.8 %, showing excellent cyclic degradation stability. An interfacial solar steam generator (ISSG) was assembled using the superhydrophobic fabric as the support layer and a polypyrrole sponge as the photothermal layer, whose evaporation efficiency under one sun reached 2.8376 kg·m−2·h−1, with a photothermal conversion efficiency of 92.255 %. This ISSG demonstrates excellent wastewater purification capabilities. Interfacial evaporation devices show promising prospects in solar-powered wastewater purification, which further expand the use of interfacial evaporation to solve the problem of water scarcity.

Advancements in superhydrophobic foam materials for efficient oil-water separation: Modification techniques and future applications

Advancements in superhydrophobic foam materials for efficient oil-water separation: Modification techniques and future applications

Development of corrosion-resistant hydrophobic Zn/ZnO composite coatings on steel substrates

Abstract The surface engineering technique evolved, making it easier to protect steel from harsh and corrosive environments. Corrosion is an enduring problem for steel that cannot be completely eliminated but can be reduced to the bare minimum. Traditional methods like galvanization and painting still exist, but hydrophobic coatings are efficient and mostly used to protect the steel from deterioration. In this work we have used nano composite hydrophobic coatings among Zn (galvanized), ZnO, and Zn/ZnO on steel samples to enhance efficiency and effectiveness in reducing corrosion rate. Electrodeposition techniques are used to incorporate the coating deposits. Spark emission spectroscopy and x-ray Fluorescence elemental analysis shows the composition of bare and galvanized steel. The x-ray Diffraction analysis (XRD) analysis proved that Zn/ZnO phases are present in coatings. The results of scratch test revealed that the bond strength increased in the hydro-Zn/ZnO-coated samples as compared to the Zn or Zn/ZnO-coated samples. Furthermore, Scanning Electron Microscopy (SEM) analysis revealed the formation of a new layer on the substrate’s surface, causing it to become rough and exhibiting growing nanostructure properties. The contact angle test proves the hydrophobic nature of composite coatings on the steel samples. The STA Zn/ZnO, coating shows the super hydrophobicity with the lowest corrosion rate, at 0.04 mm/area.

A green urethane coating for mechanically durable superhydrophobic fabric

A green urethane coating for mechanically durable superhydrophobic fabric

Washable Superhydrophobic Cotton Fabric with Photothermal Self-Healing Performance Based on Nanocrystal-MXene.

Superhydrophobic fabrics suffer from being commonly penetrated by moisture after laundering, seriously deteriorating their water repellency after air drying. Numerous researchers have successfully recovered superhydrophobicity by drying in fluid ovens; however, high energy consumption and equipment dependence limit practical applications. Herein, the superhydrophobic photothermal self-healing cotton fabric (SPS cotton fabric) was fabricated by depositing a composite layer of cellulose nanocrystal-MXene (C-MXene) and polyacrylate (PA) coatings on the cotton cloth. Superior photothermal conversion of the SPS cotton fabric performance enables its 10.5-56.8 °C greater temperature than that of the pure hydrophobic cotton fabric under different simulated solar light intensities. After washing, the SPS cotton fabric can spontaneously restore superhydrophobicity with ≈100% efficiency by 30 mW·cm-2 solar light irradiation; in contrast, the single superhydrophobic fabrics recover only ≈71.2%. Even after 10 washing cycles, the recovery efficiency of the SPS cotton fabric only decreases by 0.1%, exhibiting excellent laundering durability. The SPS cotton fabric can retain ultralong time antifrosting (2760 s) and antifreezing (4080 s) capacities due to sustainable water repellency. Remarkably, the excellent self-healing capability of the SPS cotton fabric is attributed to the fact that the coiled nonpolar alkane chains can be restored to a straight state by autothermal drive, confirmed through element analyses and molecular dynamics simulations.

Unraveling the mystery: effect of trapped air on platelet adhesion on hydrophobic nanostructured titanium dioxide.

Nature-inspired superhydrophobic materials have attracted considerable interest in blood-contacting biomedical applications due to their remarkable water-repellent and self-cleaning properties. However, the interaction mechanism between blood components and superhydrophobic surfaces remains unclear. To explore the effect of trapped air on platelet adhesion, we designed four distinct hydrophobic titanium dioxide (TiO2) nanostructures with different fractions of trapped air. Ultrasonication was used to remove trapped air, allowing for direct comparison between hydrophobic surfaces with and without observable trapped air. The results demonstrate that all four kinds of hydrophobic materials significantly reduce platelet adhesion, regardless of observable trapped air. As nanostructure size increases, the proportion of air also increases, trapped air reduces fibrinogen adsorption but increases platelet adhesion, particularly in the largest nanostructures with superhydrophobicity. Upon air removal, protein adsorption increases compared to the same sample with air, while platelet adhesion decreases. This indicates that trapped air reduces protein adsorption but unexpectedly enhances platelet adhesion, which is contrary to our intuitive expectations. Conversely, hydrophobic surfaces without trapped air minimize platelet adhesion. To gain a better understanding of this phenomenon, we propose an interpretable model. Overall, this study challenges conventional assumptions and offers new insights for the design and application of superhydrophobic materials.

Drop Dynamics during Condensation on Superhydrophobic Surfaces in Vapor Shear Flow.

Accurate models for predicting drop dynamics, such as maximum drop departure sizes, are crucial for estimating heat transfer rates during condensation on superhydrophobic (SH) surfaces. Previous studies have focused on examining the heat transfer rates for SH surfaces under the influence of gravity or vapor flowing over the surface. This study investigates the impact of surface solid fraction and texture scale on drop mobility in a condensing environment with a humid air flow. Experiments recorded condensation with varying surface feature sizes from micro- to nano scale under different flow rates. Video analysis detected the drop-size distribution and maximum drop departure sizes. Particle image velocimetry (PIV) provided accurate shear force representations. Results showed that the maximum drop departure sizes decreased with lower surface solid fractions and higher flow rates. A force balance analysis revealed that coalescence-induced drop jumping aids drop departure. Different drop behaviors due to coalescence were linked to surface characteristics. The study quantified drop jump distances under shear force during condensation on SH surfaces, and found that jump distances increased when coalescing drop sizes were similar. Based on these findings, a method for tuning SH surfaces to control drop size at coalescence and departure was suggested. Drop mobility was measured in terms of Bond and Capillary numbers, showing a dependence on surface solid fraction and pitch size. By combining these into surface slip length, it was shown that drop mobility increases with increasing slip length.

Autonomous Anticoagulation on a Biomimetic Al-Based Hierarchical Surface.

Studies targeting the blood repellency and autonomous anticoagulation of superhydrophobic (SH) surfaces are potentially valuable for their application in blood contact. The anticoagulation abilities and potential mechanisms of different SH surfaces urgently need to be revealed. In this study, a range of microprotrusion arrays on Al substrates with varying spacings via laser ablation through the utilization of organic adsorption and siloxane coupling reactions were fabricated. Consequently, gridded SH Al-based surfaces were prepared, and their blood-repellency and autonomous anticoagulation properties were evaluated. In vitro experiments demonstrated the effectiveness of these surfaces in preventing nonspecific protein adsorption and platelet adhesion, and the surfaces exhibited no indications of hemolysis or toxicity. Remarkably, the SH surfaces maintained good antiplatelet adhesion and platelet activation inhibition properties after 7 days of incubation in platelet-rich plasma, and the anticoagulation capacity of different SH surfaces was compared with elements analysis on the surfaces. Specifically, the SH Al surface exhibited low protein adsorption when incubated with 10 mg/mL of bovine serum albumin solution. Furthermore, this study illustrated the relationship between the hierarchical micronano structure of the SH surfaces and their autonomous anticoagulant behavior. The integration of a readily available SH surface with autonomous anticoagulant ability represents a promising strategy for the application of metallic materials in medical devices involving blood contact.

Nano- and Micro-SiO2 With Integrated Green Chemistry-Based Superhydrophobic Coating for Robust Antifouling and Anticorrosion Properties.

With increasing energy demands, the need for coating materials with exceptional superhydrophobic properties has grown substantially. However, the widespread use of fluorinated compounds, solvents, and polymer-based synthetic materials has led to heightened levels of microplastics and pollutants. Here, we used a self-curing, solvent-free, and recyclable polyester polyol polymer material combined with (5 and 6.5 μm) micro- and nanosized SiO2 (μ-SiO2 and n-SiO2) particles to create superhydrophobic coatings with contact angles above 170° and low roll-off angle. They were applied for self-cleaning, antifouling, and anticorrosion purposes and tested for stability in hot water, steam, and ultrasound. Both μ-SiO2 particles mixed with n-SiO2 exhibited excellent improvement in antifouling properties. Furthermore, 5 μm SiO2 incorporated with n-SiO2 demonstrated significantly higher resistance in a 62-cycle sandpaper abrasion test and maintained a contact angle above 150°, whereas this angle was lower for the 6.5 μm SiO2 coating after 30 cycles. These results suggest that 6.5 μm SiO2 offers less resistance to applied force due to its irregular roughness. However, in scenarios with lower forces, such as water drop tests, both coatings easily withstand a drop count of 3000. Additionally, electrochemical polarization curve analysis, AC impedance analysis, and seawater immersion tests confirmed the robust corrosion resistance of the superhydrophobic material.

Exploration of Key Factors in the Preparation of Highly Hydrophobic Silica Aerogel from Rice Husk Ash Assisted by Machine Learning.

To expand the applications of hydrophobic silica aerogels derived from rice husk ash (HSA) through simple traditional methods (without adding special materials or processes), this paper employs machine learning to establish mathematical models to identify optimal conditions for extracting water glass and investigates how preparation conditions and heat treatment temperatures affect properties such as the porosity and hydrophobicity of HSA. The results indicate that the decision tree regression model provides the most accurate predictions for the extraction rate and modulus of water glass. Notably, the water contact angle of HSA produced using nitric acid as a catalyst can reach as high as 159.5°, classifying it as a superhydrophobic material. Additionally, while moderately increasing the concentration of the hydrophobic modifier enhances HSA's hydrophobicity, it concurrently reduces its porosity. The HSA maintained hydrophobicity until 500 °C. The pore structure of HSA collapsed gradually with the increase in heat temperature. After treatment at 700 °C, HSA lost its hydrophobicity and the porous structure was severely damaged. Compared with silica aerogel using traditional silicon sources, the damage to pore structure and the crystallization occurred at lower temperatures, but the hydrophobicity remained at higher temperatures.

Advancements in Superhydrophobic Paper-Based Materials: A Comprehensive Review of Modification Methods and Applications.

Superhydrophobic paper-based functional materials have emerged as a sustainable solution with a wide range of applications due to their unique water-repelling properties. Inspired by natural examples like the lotus leaf, these materials combine low surface energy with micro/nanostructures to create air pockets that maintain a high contact angle. This review provides an in-depth analysis of recent advancements in the development of superhydrophobic paper-based materials, focusing on methodologies for modification, underlying mechanisms, and performance in various applications. The paper-based materials, leveraging their porous structure and flexibility, are modified to achieve superhydrophobicity, which broadens their application in oil-water separation, anti-corrosion, and self-cleaning. The review describes the use of these superhydrophobic paper-based materials in diagnostics, environmental management, energy generation, food testing, and smart packaging. It also discusses various superhydrophobic modification techniques, including surface chemical modification, coating technology, physical composite technology, laser etching, and other innovative methods. The applications and development prospects of these materials are explored, emphasizing their potential in self-cleaning materials, oil-water separation, droplet manipulation, and paper-based sensors for wearable electronics and environmental monitoring.

PH-Responsive superhydrophobic fabric based on AgNP/copolymer composites for controllable oil–water separation

pH-Responsive superhydrophobic fabric based on AgNP/copolymer composites for controllable oil–water separation

Scalable Fabrication of Light-Responsive Superhydrophobic Composite Phase Change Materials via Bionic-Engineered Wood for Solar–Thermal Energy Management

The growing demand for sustainable energy storage solutions has underscored the importance of phase change materials (PCMs) for thermal energy management. However, traditional PCMs are always inherently constrained by issues such as leakage, poor thermal conductivity, and lack of solar energy conversion capacity. Herein, a multifunctional composite phase change material (CPCM) is developed using a balsa-derived morphology genetic scaffold, engineered via bionic catechol surface chemistry. The scaffold undergoes selective delignification, followed by a simple, room-temperature polydopamine (PDA) modification to deposit Ag nanoparticles (Ag NPs) and graft octadecyl chains, resulting in a superhydrophobic hierarchical structure. This superhydrophobicity plays a critical role in preventing PCM leakage and enhancing environmental adaptability, ensuring long-term stability under diverse conditions. Encapsulating stearic acid (SA) as the PCM, the CPCM exhibits exceptional stability, achieving a high latent heat of 175.5 J g−1 and an energy storage efficiency of 87.7%. In addition, the thermal conductivity of the CPCM is significantly enhanced along the longitudinal direction, a 2.1-fold increase compared to pure SA, due to the integration of Ag NPs and the unidirectional wood architecture. This synergy also drives efficient photothermal conversion via π-π stacking interactions of PDA and the surface plasmon effects of Ag NPs, enabling rapid solar-to-thermal energy conversion. Moreover, the CPCM demonstrates remarkable water resistance, self-cleaning ability, and long-term thermal reliability, retaining its functionality through 100 heating–cooling cycles. This multifunctional balsa-based CPCM represents a breakthrough in integrating phase-change behavior with advanced environmental adaptability, offering promising applications in solar–thermal energy systems.

Review of exploration of aircraft de/anti-icing mechanism and airborne application of superhydrophobic materials

The aircraft surface icing changes the flight dynamics characteristics of the aircraft and seriously threatens flight safety. Therefore, aircraft de/anti-icing technologies are of great significance for safe flight. The basic principle, type, and influence of aircraft icing are analyzed and the existing de/anti-icing technology methods and their advantages and disadvantages are compared. Literature review of superhydrophobic materials was comprehensively conducted, and its specific conditions (superhydrophobic property failure) were analyzed, especially the existing problems and challenges. A hybrid de/anti-icing system was proposed for the defects of a single de/anti-icing system, and several hybrid de/anti-icing systems were introduced and compared with the single de/anti-icing system. In addition, aiming at the possible problems in the application of superhydrophobic materials, an aircraft de/anti-icing system combining loop heat pipe and superhydrophobic materials is presented. Benefiting from the efficient heat transfer mode of the loop heat pipe system and the superhydrophobic effect of the superhydrophobic material, this method can not only reduce the energy consumption of the aircraft?s de/anti-icing system, but also reduce the formation of secondary icing. Finally, the issues of superhydrophobic coating and hybrid de/anti-icing systems are analyzed and prospected.

Exploration of halogen-free sustainable superhydrophobic materials for surface protection from multi-contaminants in all weather conditions.

The complex synthetic approach and utilization of toxic chemicals restrain the commercialization of numerous existing superhydrophobic materials. This article focuses on the development of a halogen-free superhydrophobic material for self-cleaning applications. HMDS-modified MCM-41 is employed as the base material. Silanization within the silica-framework is strategically improved by introducing the concept of surface-acidity enhancement by suitable heteroatom (Al, Ti and Zr) incorporation. The role of heteroatoms in defining the surface acidity of MCM-41 is analyzed in terms of solubility limit, ionic radii and electronegativity of the heteroatoms. Additionally, this work exclusively discusses the solvent selection criteria for the synthesis of hydrophobic materials and their role in enhancing hydrophobicity, evaluated via UV-visible turbidity measurements. Based on extensive studies, silane modified 25% Al-MCM-41 dispersed in acetonitrile exhibits exceptional water repellence with a water contact angle of 172.4 ± 0.7°. Higher electropositivity and the trivalent bonding nature of Al facilitate efficient silane modification and reduced surface OH concentration, leading to improved material hydrophobicity. Remarkable self-cleaning capability combined with durability and resilience towards diverse harsh conditions strengthen the practical viability of the designed material. Life cycle assessment (LCA) suggested that the material exhibits a smaller environmental footprint in terms of 18 selected midpoint indicators compared to the state-of-the-art materials.

Superhydrophobic and oleophobic luminescent composite materials for oxygen sensing in fuel-laden atmospheres

Accurate measurement and monitoring of oxygen concentration in fuel-laden atmospheres is crucial for reducing the risk of fire and explosion. Oxygen sensors based on fluorescence quenching are suitable for such...

Controllable synthesis and functionalization of SiO2 nanoflower for fluorine-free superhydrophobic fabrics-based oil/water mixture and emulsion separation

The fabrication of superhydrophobic fabrics has gained significant interest for their potential in applications like oil/water separation, yet conventional methods often involve fluorine-based materials, raising environmental concerns. Herein, we introduce...

Robust MXene-based superhydrophobic fabrics for efficient separation of high-viscosity lubricating oil/water emulsions

Deteriorated lubricating oil poses separation challenges due to its high viscosity. To address this issue, this paper introduces a superhydrophobic cotton fabric prepared via a one-pot method using PDA/MXene/SiO2. The...

Micron-level aggregate initiated ultra hydrophobicity with enhanced intumescent flame retardancy, smoke suppression, and toughness simultaneously in polypropylene

Micron-level aggregate initiated ultra hydrophobicity with enhanced intumescent flame retardancy, smoke suppression, and toughness simultaneously in polypropylene