Polydopamine/SiO2 Hybrid Structured Superamphiphobic Fabrics with Good Photothermal Behavior

Antireflective Superhydrophobic and Robust Coating Based on Chitin Nanofibers and Methylsilanized Silica for Outdoor Applications

Antireflective coatings with superhydrophobicity have many outdoor applications, such as solar photovoltaic panels and windshields. In this study, we fabricated an omnidirectional antireflective and superhydrophobic coating with good mechanical robustness and environmental durability via the spin coating technique. The coating consisted of a layer of phytic acid (PA)/polyacrylamide (PAM)/calcium ions (Ca2+) (referred to as Binder), an antireflective layer composed of chitin nanofibers (ChNFs), and a hydrophobic layer composed of methylsilanized silica (referred to as Mosil). The transmittance of a glass slide with the Binder/ChNFs/Mosil coating had a 5.2% gain at a wavelength of 550 nm, and the antireflective coating showed a water contact angle as high as 160° and a water sliding angle of 8°. The mechanical robustness and environmental durability of the coating, including resistance to peeling, dynamic impact, chemical erosion, ultraviolet (UV) irradiation, and high temperature, were evaluated. The coating retained excellent antireflective capacity and self-cleaning performance in the harsh conditions. The increase in voltage per unit area of a solar panel with a Binder/ChNFs/Mosil coating reached 0.4 mV/cm2 compared to the solar panel exposed to sunlight with an intensity of 54.3 × 103 lx. This work not only demonstrates that ChNFs can be used as raw materials to fabricate antireflective superhydrophobic coatings for outdoor applications but also provides a feasible and efficient approach to do so.

Synergistic Effect of Microconvex Texture and Particle Medium on the Tribological Property of the Rubber Sliding Interface

In this study, we examined how surface topography and particle medium interact to affect the tribological performance of rubber sliding interfaces, uncovering the mechanisms of particle lubrication under various conditions. We found that microtextured surfaces, created using a mold transfer method, modestly reduced the friction coefficient of rubber under both dry and lubricated states, primarily by altering the real contact area. Additionally, the presence of different microconvex textures on the surface topography significantly influenced rubber's tribological properties. Our three-dimensional morphological analysis revealed that microtextured rubber surfaces with higher Sa, Sku, and Sal and lower Str values consistently showed lower friction coefficients during sliding. The friction mechanism was attributed to the combined effects of the material properties, surface topography, and contact area. With the addition of a particle medium, the dry friction coefficient of the rubber interface decreased but exhibited an initial increase, followed by a decrease with increasing particle diameter. When particles were mixed with a water-based cutting fluid, the concentration, diameter, and wettability of the particles significantly impacted the tribological properties due to the synergistic effects of surface topography and particle lubrication. This work enhances our understanding of tribological control for viscoelastic materials through surface design, providing a theoretical basis for the tribological optimization of rubber surfaces.

Polymerization-Induced Hierarchical Hybrid Particles from Siloxane Emulsification Endowing Polyurethane Composite Coating with Superhydrophobicity, Thermal Insulation, and Fluorescence

Hierarchically structural particles (HSPs) are highly regarded as favorable nanomaterials for superhydrophobic coating due to their special multiscale structure and surface physicochemical properties. However, most of the superhydrophobic coatings constructed from HSPs are monofunctional, constraining their broader applications. Moreover, traditional methods for constructing HSPs mostly rely on complicated chemical routes and template removal. Herein, we propose an innovative strategy (one-pot method) for producing multifunctional hierarchical hybrid particles (HHPs). Polysilsesquioxane (PSQ), generated from hydrolysis condensation of methyltriethoxylsilane, is used as the sole stabilizer to anchor on the surface of styrene and short fluoroalkyl compound tridecafluorooctyl acrylate comonomers droplets, forming a mesoporous PSQ shell. Subsequently, the comonomers inside of the shell perform restricted polymerization to generate the HHP due to the driving of the mesoporous capillary force. The HHP is then mixed with waterborne polyurethane (WPU) to develop a robust nanocomposite coating (WPU-HHP). Through the deliberate design of the HHP components, the WPU-HHP coating has thermal insulation, photoluminescence properties, and the ability to achieve a wettability transition during abrasion. Our research has achieved the integration of multifunctionality in one waterborne hybrid system, broadening the application areas of nanocomposite coatings.

Stable and Durable Superhydrophobic Cotton Fabrics Prepared via a Simple 1,4-Conjugate Addition Reaction for Ultrahigh Efficient Oil-Water Separation

Superhydrophobic materials used for oil-water separation have received wide attention. However, the simple and low-cost strategy for making durable superhydrophobic materials remains a major challenge. Here, this work reports that stable and durable superhydrophobic cotton fabrics can be prepared using a simple two-step impregnation process. Silica nanoparticles are surface modified by hydrolysis condensation of 3-aminopropyltrimethoxysilane (APTMS). 1,4-conjugate addition reaction between the acrylic group of cross-linking agent pentaerythritol triacrylate (PETA) and the amino group of octadecylamine (ODA) forms a covalent cross-linked rough network structure. The long hydrophobic chain of ODA makes the cotton fabric exhibit excellent superhydrophobic properties, and the water contact angle (WCA) of the fabric surface reaches 158°. The modified cotton fabric has good physical and chemical stability, self-cleaning, and anti-fouling. At the same time, the modified fabric shows excellent oil/water separation efficiency (98.16% after 20 cycles) and ultrahigh separation flux (15413.63 L m-2 h-1) due to its superhydrophobicity, superoleophilicity, and inherent porous structure. The method provides a broad prospect in the future diversification applications of oil/water separation and oil spill cleaning.

Fibrous Structures: An Overview of Their Responsiveness to External Stimuli towards Intended Application

In recent decades, the interest in responsive fibrous structures has surged, propelling them into diverse applications: from wearable textiles that adapt to their surroundings, to filtration membranes dynamically altering selectivity, these structures showcase remarkable versatility. Various stimuli, including temperature, light, pH, electricity, and chemical compounds, can serve as triggers to unleash physical or chemical changes in response. Processing methodologies such as weaving or knitting using responsive yarns, electrospinning, as well as coating procedures, enable the integration of responsive materials into fibrous structures. They can respond to these stimuli, and comprise shape memory materials, temperature-responsive polymers, chromic materials, phase change materials, photothermal materials, among others. The resulting effects can manifest in a variety of ways, from pore adjustments and altered permeability to shape changing, color changing, and thermal regulation. This review aims to explore the realm of fibrous structures, delving into their responsiveness to external stimuli, with a focus on temperature, light, and pH.

Photothermal, superhydrophobic, conductive, and anti-UV cotton fabric loaded with polydimethylsiloxane-encapsulated copper sulfide nanoflowers

Multifunctional textiles have attracted widespread attention with the improvement of awareness of health. Especially, the fluorine-free superhydrophobic and conductive cellulose fiber-based fabrics have received intensive interest due to their broad and high-value applications. Herein, the copper sulfide nanoflowers were in-situ deposited on cotton fabric followed by polydimethylsiloxane (PDMS) treatment for encapsulating CuS nanoflowers and obtaining superhydrophobicity, recorded as Cot@PTA@CuS@PDMS. Cot@PTA@CuS@PDMS possesses superhydrophobicity with contact angles of 153.0 ± 0.4°, photothermal effect, excellent UV resistance, good conductivity, and anti-fouling. Interestingly, the resistance of Cot@PTA@CuS@PDMS is significantly reduced from 856.4 to 393.1 Ω under simulated sunlight irradiation with 250 mW/cm2. Notably, the resistance can be slightly recovered after shutting off simulated sunlight. Besides, Cot@PTA@CuS@PDMS has efficient oil-water separation efficiency for corn germ oil and castor oil, respectively. Briefly, this work provides a novel, facile, and promising strategy to fabricate multifunctional fiber-based textiles with the reversible change of resistance under simulated sunlight irradiation, inspiring more scholars to control the resistance change of textiles by light irradiation.

Silica-Based Superhydrophobic and Superoleophilic Cotton Fabric with Enhanced Self-Cleaning Properties for Oil-Water Separation and Methylene Blue Degradation

Superhydrophobic textiles with multifunctional characteristics are highly desired and have attracted tremendous research attention. This research employs a simple dip-coating method to obtain a fluorine-free silica-based superhydrophobic and superoleophilic cotton fabric. Pristine cotton fabric is coated with SiO2 nanoparticles and octadecylamine. SiO2 nanoparticles are anchored on the cotton fabric to increase surface roughness, and octadecyl amine lowers the surface energy, turning the hydrophilic cotton fabric into superhydrophobic. The designed cotton fabric exhibits a water contact angle of 159° and a sliding angle of 7°. The prepared cotton fabric is characterized by attenuated total reflectance-fourier transform infrared spectroscopy, X-ray diffraction, atomic force microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. In addition, the coated fabric reveals excellent features, including mechanical and chemical stability, superhydrophobicity, superoleophilicity, and the self-cleaning ability. SiO2 nanoparticles and octadecylamine-coated cotton fabric demonstrate exceptional oil-water separation and wastewater remediation performance by degrading the methylene blue solution up to 89% under visible light. The oil-water separation ability is tested against five different oils with more than 90% separation efficiency. This strategy has the advantages of low-cost precursors, a simple and scalable coating method, enhanced superhydrophobicity and superoleophilicity, self-cleaning ability, efficient oil-water separation, and exceptional wastewater remediation performance.

Characterization of Surface Modifications in Oxygen Plasma-Treated Teflon AF1600

We explore the surface properties of Teflon AF1600 films treated by oxygen plasma with various procedure parameters. Contact angle (CA) measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron microscopy (XPS) are employed to investigate the wetting behavior, surface topography, and chemical composition, respectively. While the etched thickness reveals a linear relationship to the applied plasma energy, the surface presents various wetting properties and topographies depending on the plasma energy: low advancing and zero receding CA (1 kJ), super high advancing and zero receding CA (2-3 kJ), and super high advancing and high receding CA (≥4.5 kJ) for the wetting behaviors; pillar-like (≤6 kJ) and fiber-like (>6 kJ) nanoscaled structures for the topographies. The results of XPS analysis reveal slight changes in the presence of O- and F-components (<4%) after oxygen plasma treatment. Furthermore, we discuss the applicability of the Wenzel and Cassie-Baxter equations and employ the Friction-Adsorption (FA) model, where no wetting state and structure-related parameters are needed, to describe the CAs on the plasma-treated surfaces. Additionally, we conduct electrowetting experiments on the treated surfaces and find that the experimental results of the advancing CA are in good agreement with the predictions of the FA model.

Impalement-Resistant, Mechanically Stable, and Anti-Static Superamphiphobic Coatings Enabled by Solvent Regulation and Their Application in Anti-Icing

Superamphiphobic coatings have good application prospects in many fields but are limited by their low impalement resistance, weak mechanical stability, and easy adhesion of tiny droplets. Here, impalement-resistant, mechanically stable, and antistatic superamphiphobic coatings were fabricated by spraying a mixture of conductive carbon black (CB), silicone-modified polyester adhesive/fluorinated SiO2 microspheres onto Al alloy. The microspheres were obtained by adhesive phase separation and the binding of fluorinated SiO2 to them. The morphology, superamphiphobicity, impalement resistance, and mechanical stability of the coatings could be regulated by using solvents with different boiling points. As a result, the coatings simultaneously exhibited outstanding mechanical stability, impalement resistance, and superamphiphobicity. The addition of conductive CB endowed the coatings with good antistatic and tiny droplet repellent properties. In addition, the coatings exhibited good anti-icing properties due to the steady air layer at the solid-liquid interface and the very small contact area between them. We suppose that the coatings are very promising for practical application in various fields, including anti-icing, due to their outstanding comprehensive properties and simple preparation process.

Hydrophobic Composite Foams with Asymmetric Gradient Sandwich Structure for Excellent Electromagnetic Interference Shielding and Photothermal Response

The evolution of contemporary electronics urgently requires the use of versatile electromagnetic interference (EMI) shielding materials in complex environments. Interlayer polydimethylsiloxane (PDMS)/Fe3O4@multiwalled carbon nanotubes (MWCNTs) foams were prepared by a simple physical foaming method with excellent flexibility and electromagnetic wave absorption. The bottom nickel aramid paper (NiP) layer creates a dense conductive network by chemical plating technology, which ensures excellent EMI effectiveness. The upper carbon black (CB)/Fe3O4 layer further improves the absorption performance via conductive loss and magnetic loss. With the effective layout of the impedance matching layer, absorbing layer, and conductive shielding layer, the CB/Fe3O4-PDMS/Fe3O4@MWCNTs-NiP composite material achieves an EMI shielding effectiveness (EMI SE) of 61.7 dB and an absorption coefficient of 0.58 at X-band. In addition, the composite foam provides photothermal conversion and hydrophobicity due to the effective stacking of PDMS and CB/Fe3O4. Thus, the multifunctional composite foam presents a broad range of possible applications, benefiting EMI shielding as well as other specific areas.

Preparation of a Stable Superhydrophobic Mortar Surface Using a One-Step Method

Research efforts have intensified on developing superhydrophobic surfaces on concrete structures to limit the damage caused by the natural porosity and hydrophilicity of cementitious materials. However, the feasibility idea is impeded by the complex preparation process and weak adhesion/stability performance. Therefore, superhydrophobic coatings were rapidly prepared on mortar surfaces by a straightforward and effective one-step method using zinc oxide (ZnO) modified with stearic acid and epoxy resin. The microstructure, physical/chemical properties, hydrophobic properties, and stability of the coatings were systematically investigated. The experimental results showed that the water contact angle of the samples reached a maximum value of 164.2° and a sliding angle of 4.6° when the stearic acid content was 0.5 g. The water absorption of the coated superhydrophobic mortar was reduced by approximately 61% compared to that of ordinary mortar, and neither particulate pollutants nor liquid pollutants could contaminate the superhydrophobic mortar. The coating maintained a superhydrophobic state and exhibited good physical durability after sandpaper abrasion, tape peeling, and high-temperature resistance tests. The water cluster diffusion coefficient on surface of the ordinary coating was 0.1645 × 10-4 and 0.0328 × 10-4 cm2/s on surface of the modified coating after molecular dynamics simulation.

Development of Adjustable High- to Low-Adhesive Superhydrophobicity Using Aligned Electrospun Fibers

Superhydrophobic surfaces based on electrospun fibrous structures exhibit advantages of additive manufacturing and enable the passage of gases. Compared to randomly deposited fibers, directionally aligned fibers improve the control of surface wetting by a specified fiber orientation and predictable liquid-fiber contact interface. In this article, we create superhydrophobicity with adjustable adhesion based on the understanding of droplet wetting behavior on directionally aligned fibers. Directionally aligned polystyrene fibers with different diameters and interfiber distances (l) are produced using electrospinning with a rotating fin collector. The wetting behavior of droplets on the surfaces dressed by aligned fibers is characterized, and a thermodynamic model of wetting behavior is established to guide the experimental studies. As a result, high-adhesive superhydrophobicity is achieved on weak hydrophobic substrate surfaces dressed by aligned polystyrene fibers with a diameter of 1.8 μm and l between 5 and 130 μm. Water droplets (2 μL) exhibit a maximum contact angle of 156° and adhere to the fiber-dressed surfaces by tilting upside down. Low-adhesive superhydrophobicity is achieved by introducing an additional layer of aligned fibers to increase the transition energy barrier. On the dual-layer structure with an upper-layer l of 9 μm, droplets show a contact angle of 155° and can readily roll off the surface. Moreover, increasing the upper-layer l to 15 μm reserves the surface to high-adhesive superhydrophobicity.

Advances in the Research of Photo, Electrical, and Magnetic Responsive Smart Superhydrophobic Materials: Synthesis and Potential Applications

With the rapid advancement of technology, the wettability of conventional superhydrophobic materials no longer suffice to meet the demands of practical applications. Intelligent responsive superhydrophobic materials have emerged as a highly sought-after material in various fields. The exceptional superhydrophobicity, reversible wetting, and intelligently controllable characteristics of these materials have led to extensive applications across industries, including industry, agriculture, defense, and medicine. Therefore, the development of intelligent superhydrophobic materials with superior performance, economic practicality, enhanced sensitivity, and controllability assumes utmost importance in advancing technology worldwide. This article provides a summary of the wettability principles of superhydrophobic surfaces and the mechanisms behind intelligent responsive superhydrophobicity. Furthermore, it reviews and analyzes the recent research progress on light, electric, and magnetic responsive superhydrophobic materials, encompassing aspects such as material synthesis, modification, performance, and responses under diverse external stimuli. The article also explores the challenges associated with different types of responsive superhydrophobic materials and the unique application prospects of light, electric, and magnetic responsive superhydrophobic materials. Additionally, it outlines the future directions for the development of intelligent responsive superhydrophobic materials.

Photothermal Superhydrophobic Cotton Fabric Based on Silver Nanoparticles Cross-Linked by Polydopamine and Polyethylenimide

Photothermal materials that can convert solar energy into heat energy through photothermal conversion have attracted extensive attention, but these materials are easily polluted by the environment. Here, we propose a simple and effective strategy for constructing photothermal superhydrophobic cotton fabrics with self-cleaning ability. The PDA@PEI@GA@Ag@PDMS-coated cotton fabric can achieve good superhydrophobicity (water contact angle: 159.6°) by a simple dipping method and mussel-inspired dopamine surface modification, which is regulated by the mass of dopamine, the mass of silver nitrate, and the concentration of polydimethylsiloxane (PDMS). The coated cotton fabric has good physical and chemical stability. Meanwhile, the coated cotton fabric has excellent self-cleaning and antifouling properties. The superhydrophobic PDA@PEI@GA@Ag@PDMS fabric exhibits excellent and stable photothermal properties, with the surface temperature reaching 70.4 °C under simulated sunlight with a current of 20 A. This photothermal superhydrophobic fabric with self-cleaning properties is expected to be applied in the field of photothermal conversion.

Antiadhesion Superhydrophobic Bipolar Electrocoagulation Tweezers with High Conductivity and Stability

Irregularly shaped electrosurgical devices face significant challenges in electrosurgery due to serious blood and tissue adhesion. Superhydrophobic surfaces inspired by lotus leaves have attracted great attention for their promising antiadhesion properties. However, there are few methods for efficiently preparing superhydrophobic irregularly shaped bipolar electrocoagulation tweezers (BETs). Herein, we propose a simple and environmentally friendly method to fabricate antiadhesion superhydrophobic surfaces on BETs. The superhydrophobicity is obtained by combining laser texturing to form rough structures and low surface energy modification via stearic acid. The formation mechanism of superhydrophobicity is investigated through analyzing microstructures and chemical compositions by scanning electron microscopy, white-light interferometry, and X-ray photoelectron spectroscopy. The functionalized BET surfaces exhibit excellent water repellency with a contact angle of 159.6°, a roll-off angle of 1°, and a surface energy of 14.3 mJ/m2, possessing excellent antiadhesion properties against blood, chicken breast tissue, and pork tissue. Compared with ordinary BETs, the mass of blood, pork tissue, and chicken breast tissue adhered to the superhydrophobic BET is reduced by 97.70, 70.34, and 75.35%, respectively. Moreover, the superhydrophobic BETs have excellent conductivity and maintain good antiadhesion properties after low-temperature storage for 2 weeks, after being impacted by sand and blood and 30 cycles of tape peeling tests. With outstanding antiadhesion performance, the superhydrophobic BET may have promising application prospects in the electrosurgery field.

Enhancing Self-Healing and Adhesion Bonding Properties: Investigating the Promising Potential of Ce-ZIF8 MOF Hybrid Thin Films as pH-Responsive Nanocoatings

Further modification of the pre-treated steel surface with cerium conversion coating was performed using a novel porous coordination polymer (PCP) based on zeolitic imidazole framework-8 (ZIF8) in order to reduce the defect and disorders of the surface. The treated mild steels (MS) with Ce (MS/Ce) and Ce-ZIF8 (MS/Ce-ZIF8) were characterized by the GIXRD, Raman, and FT-IR, and via contact angle and FE-SEM, their surface features were investigated. The protection performance of the samples against corrosion was evaluated in the saline solution media using electrochemical impedance spectroscopy (EIS, in the long term) and polarization tests. The results evidenced that applying the ZIF8 nanoparticles onto the Ce-treated steel surface increased the total resistance value after 24 h of immersion (49.47%). Afterward, the ZIF8-modified coating (MS/Ce and MS/Ce-ZIF8) impact on the epoxy coating protection function was characterized by EIS (in the scratched form), salt spray (5 wt % salts), cathodic disbonding (at 25 °C), and pull-off tests. The EIS outcomes of the scratched coatings proved approximately a 51.29% increase in R_t of the MS/Ce-ZIF8/EC sample compared with the MS/EC sample after 24 h of immersion. The cathodic disbonding test results after 24 h of exposure revealed that the delamination area of the coating decreased in the modified sample, and the delamination radius of the epoxy coating was about 4.78, 2.96, and 2.0 mm for the MS/EC, MS/Ce/EC, and MS/Ce-ZIF8/EC samples, respectively.

Superhydrophobicity Mechanism and Nanoscale Profiling of PDMS-Modified Kaolinite Nanolayers via Ab Initio-MD Simulation and Atomic Force Microscopy Study

This study aimed to investigate the superhydrophobic mechanism of kaolinite particles modified with poly(dimethylsiloxane) (PDMS), which has potential as a superior hydrophobic coating. The study employed a combination of density functional theory (DFT) simulation modeling, characterization of the chemical properties and microstructure, contact angle measurements, and chemical force spectroscopy of atomic force microscopy. The results showed successful PDMS grafting onto the kaolinite surface, resulting in micro- and nanoscale roughness and a contact angle of 165°, indicating a successful superhydrophobic effect. The study also identified the mechanism of the hydrophobic interaction through two-dimensional micro- and nanoscale hydrophobicity images, highlighting the potential of this approach for developing new hydrophobic coatings.

Design of Waterborne Superhydrophobic Fabrics with High Impalement Resistance and Stretching Stability by Constructing Elastic Reconfigurable Micro-/Micro-/Nanostructures

Superhydrophobic fabrics have great application potential in many fields including wearable electronic devices, sports textiles, and human health monitoring, but good water impalement resistance and stretching stability are the prerequisites. Here, we report the design of waterborne superhydrophobic fabrics with high impalement resistance and stretching stability by constructing elastic reconfigurable micro-/micro-/nanostructures. Following theoretical analysis, two approaches were proposed and employed: (i) regulating distance between the microfibers of polyester fabrics to decrease the solid-liquid contact area, and (ii) forming reconfigurable two-tier hierarchical micro-/nanostructures on the microfibers by stretching during dipping to further decrease the solid-liquid contact area. The effects of microfiber distance and micro-/nanostructures on microfibers on superhydrophobicity and impalement resistance were studied. The superhydrophobic fabrics show excellent impalement resistance as verified by high-speed water impact, water jetting, and rainfall, etc. The fabrics also show excellent stretching stability, as 100% stretching and 1000 cycles of cyclic 100% stretching-releasing have no obvious influence on superhydrophobicity. Additionally, the fabrics show good antifouling property, self-cleaning performance, as well as high abrasion and washing stability. The experimental results agree with the theoretical simulation very well. We anticipate that this study will boost the development of impalement-resistant and stretching-stable superhydrophobic surfaces.

Environmentally Friendly Plastic Boats - A Facile Strategy for Cleaning Oil Spills on Water with Excellent Efficiency

In this report, we demonstrate a novel plastic boat capable of selectively and efficiently collecting spilled oils while floating on water. The boat has macroscopic openings in its vertical and curved sidewalls. It is easily, quickly, and inexpensively fabricated using an environmentally friendly polymer via a three-dimensional printing technique. Its surface is sequentially coated with nano-ceramic coating liquid and oil, which imparts favorable hydrophobic, oleophilic, and high oil-wettability properties. Using the boat prototype, a small pump system, and an oil boom-like device, we demonstrate that spilled oils with a wide range of viscosities (2.0-1000 cSt at 25-40 °C) are rapidly collected from the surface of both pure water and seawater. Remarkably, it efficiently collects oil spills on seawater under wavy conditions, and the retrieved oil does not mix with any drop of water. Moreover, the boat can be scaled up to a large size easily and has a long-term usage. By exhibiting these characteristics, our developed boat is a prominent potential device for practical oil retrieval applications.

Effects of Carbon Templates in Tetraethyl Orthosilicate-Derived Superhydrophobic Coatings

Superhydrophobic coatings have garnered significant research interest due to their potential applications in areas such as ant-icing and windows. This study focuses on the development of superhydrophobic coatings using air-assisted electrospray and the effect of different carbon additives as templates in the coating. Carbon templates, with their unique topological varieties, offer a cost-effective alternative to other patterning technologies such as photolithography. By introducing dispersed carbon black, carbon nanotubes, and graphene additives in TEOS solution, silica is given the ability of localized secondary growth on or around the carbon surfaces as well as the building structure to provide adequate roughness on the substrate surface. The templated silica formations provide a thin coating with nano-scale roughness for heightened water resistance. As compared with the template-free coating that has small silica particles, a surface roughness of 135 nm, and a water contact angle (WCA) of 101.6° (non-superhydrophobic), the carbon templating effect allowed for increased silica particle size, a surface roughness as high as 845 nm, a WCA above 160°, and the ability to maintain superhydrophobicity over 30 abrasion cycles. The morphological characteristics that resulted from the templating effect correlate directly with heightened performance of the coatings. Herein, the carbon additives have been found to serve as cheap and effective templates for silica formation in thin TEOS-derived superhydrophobic coatings.

Fabrication of Robust Waterborne Superamphiphobic Coatings with Antifouling, Heat Insulation, and Anticorrosion

Water-based superamphiphobic coatings that are environmentally friendly have attracted tremendous attention recently, but their performances are severely limited by dispersibility and mechanical durability. Herein, a dispersion of poly(tetrafluoroethylene)/SiO₂@cetyltrimethoxysilane&sodium silicate-modified aluminum tripolyphosphate (PTFE/SiO₂@CTMS&Na₂SiO₃-ATP) superamphiphobic coatings was formed by mechanical dispersion of poly(tetrafluoroethylene) emulsion (PTFE), modified silica emulsion (SiO₂@CTMS), sodium silicate (Na₂SiO₃), and modified aluminum tripolyphosphate (modified ATP). The four kinds of emulsions were mixed together to effectively solve the dispersity of waterborne superamphiphobic coatings. Robust waterborne superamphiphobic coatings were successfully obtained by one-step spraying and curing at 310 °C for 15 min, showing strong adhesive ability (grade 1 according to the GB/T9286), high hardness (6H), superior antifouling performance, excellent impact resistance, high-temperature resistance (<415 °C), anticorrosion (immersion of strong acid and alkali for 120 h), and heat insulation. Remarkably, the prepared coating surface showed superior wear resistance, which can undergo more than 140 abrasion cycles. Moreover, the composite coating with 35.53 wt % SiO₂@CTMS possesses superamphiphobic properties, with contact angles of 160 and 156° toward water and glycerol, respectively. The preparation method of superamphiphobic coatings may be expected to present a strategy for the preparation of multifunctional waterborne superamphiphobic coatings with excellent properties and a simple method.

Fabrication of Superhydrophobic and Light-Absorbing Polyester Fabric Based on Caffeic Acid

Caffeic acid (CA) was treated on the surface of polyester fabric (PET), and Fe²⁺ was used as an intermediate to form chelates with CA to increase the roughness of the polyester surface. With the addition of n-octadecyl mercaptan (SH), the mercapto group reacted with the carbon-carbon double bond of CA on the PET surface through enol click chemical reaction. Meanwhile, CA was polymerized under UV radiation, and thus CA-Fe-SH-PET was prepared. The introduction of SH with a long carbon chain reduced the surface energy of the PET, in order to endow the polyester fabric with a superhydrophobic/lipophilic function. Combined with XPS and FTIR tests, the new carbon-carbon double bond's binding energy and vibration peak were found on the fabric surface, indicating that CA was adsorbed on the PET fabric's surface. After adding SH, the double bond disappeared, demonstrating that SH and CA occurred a click chemical reaction and were grafted onto the PET fabric's surface. The water contact angle (WCA) of CA-Fe-SH-PET was about 156 ± 0.6°, and the scrolling angle (SA) was about 3.298°. The results showed that the modified polyester had a robust superhydrophobic stability in washing, mechanical friction, sun aging, seawater immersion, organic reagent, and acid-base erosion derived from the good adhesion of polymerized CA (PCA). At the same time, the modified polyester fabric had good self-cleaning, antifouling, and oil-water separation performance. It was found that the CA-Fe-SH-PET fabric had unique photothermal conversion characteristics, which can convert the absorbed ultraviolet light into thermal energy, providing a local warming effect due to rapid heating and improving the transmission speed of heavy oil (engine oil and diesel). The CA-Fe-SH-PET fabric can further prevent the transmission of ultraviolet rays, and the UV resistance of CA-Fe-SH-PET fabric is far higher than the UV resistance standard. The preparation method is simple, fast, efficient, and environmentally friendly, and it has better a potential application value in the oil-water separation field.

Superhydrophobic Polyurethane Membrane with a Biomimetically Hierarchical Structure for Self-Cleaning

In this study, a stable and durable hexadecyltrimethoxysilane (HDTMS)/thermoplastic polyurethane (TPU) superhydrophobic film is successfully prepared by a simple and low-cost two-step method, namely, carrying out biomimetically hierarchical structures and low surface energy material modification concurrently. Meanwhile, effective parameters affecting the water contact angle (WCA) are studied and optimized. More importantly, under optimum parameters, the maximum WCA is 165°, the minimum slide angle (SA) is 3°, and the adhesion force is 13 μN, showing good self-cleaning performance. Besides, considerable mechanical stability to withstand 4000 tension or 5000 compression cycles, breathability, and moisture penetrability, as well as chemical resistance with sustained superhydrophobic properties in various harsh environments, are presented.

Functional Microtextured Superhydrophobic Surface with Excellent Anti-Wear Resistance and Friction Reduction Properties

The wear-resistant superhydrophobic (SHB) surfaces with excellent water-repellency ability were prepared by constructing a microtextured armor on an aluminum surface. With the assistance of laser-induced microtextures, the SHB surface could keep a longer water-repellency ability and a lower friction coefficient even after repeated friction tests under different loads and at different speeds. The mechanism of microtexture-protecting SHB coating is revealed based on both theoretical and elemental analysis. Additionally, we explore the relationship between the three-dimensional topography parameters (ISO 25178) and variation of water contact angles under different test recycles. The results show that the rough surface with appropriate S_a and higher S_ku exhibits a better wear resistance, which is mainly related to the storing ability of SHB coating inside the microtextures. Moreover, the surface with appropriate S_tr exhibits excellent wear resistance, which is mainly associated with better chip-removal ability. Finally, the tribological properties of the microtextured SHB surface are researched. It is worth noting that compared with the microtextured surface without SHB coating and the SHB-coated surface without microtextures, the microtextured SHB surface has the lowest friction coefficient under dry friction because the SHB coating would largely decrease the surface energy of the interface, so the adhesion friction decreases. The microtexture armor on the surfaces would protect the wear of SHB coating, so the SHB coating inside the microtexture could continuously play the role of a particle lubricant at the sliding interface and decrease the friction force of the sliding interface. We believe that the present study would contribute to the further understanding of the constructing mechanism of anti-wear SHB surfaces and provide a new strategy for topography design of engineering surfaces with friction reduction properties.

Unveiling the Relationship of Surface Roughness on Superliquid-Repelling Properties with Randomly Distributed Rough Surface Structures

Though superliquid-repelling surfaces are universally important in the fields of fundamental research and industrial production, the understanding and development of these surfaces to impacting liquid droplets remain elusive, especially the changes of wettability states. Surface roughness is required to obtain superliquid-repelling surfaces. However, the effect of surface roughness on the transition of these surfaces' wettability states is uncertain. Herein, we unveiled the relationship of surface roughness on regulating the wettability states of superliquid-repelling surfaces with randomly distributed rough structures through experiment and calculations. The roughness was controlled via regulating the size of surface rough structures, which were formed by a facile coating method. The results indicated that the surface rough structures could impact the value of the polar component (γ_s^p) and then impact the wettability states of superliquid-repelling surfaces. Quantitatively, when the increment of surface roughness was low, the decrement of γ_s^p was low and the wettability state of the superliquid-repelling surface was superhydrophobicity. When the increment of surface roughness was high, the decrement of γ_s^p was high and the wettability state of the superliquid-repelling surface converted to superamphiphobicity. The findings will shed light onto the development of superliquid-repelling surfaces in future studies.

A versatile “3M” methodology to obtain superhydrophobic PDMS-based materials for antifouling applications

Fouling, including inorganic, organic, bio-, and composite fouling seriously affects our daily life. To reduce these effects, antifouling strategies including fouling resistance, release, and degrading, have been proposed. Superhydrophobicity, the most widely used characteristic for antifouling that relies on surface wettability, can provide surfaces with antifouling abilities owing to its fouling resistance and/or release effects. PDMS shows valuable and wide applications in many fields, and due to the inherent hydrophobicity, superhydrophobicity can be achieved simply by roughening the surface of pure PDMS or its composites. In this review, we propose a versatile “3M” methodology (materials, methods, and morphologies) to guide the fabrication of superhydrophobic PDMS-based materials for antifouling applications. Regarding materials, pure PDMS, PDMS with nanoparticles, and PDMS with other materials were introduced. The available methods are discussed based on the different materials. Materials based on PDMS with nanoparticles (zero-, one-, two-, and three-dimensional nanoparticles) are discussed systematically as typical examples with different morphologies. Carefully selected materials, methods, and morphologies were reviewed in this paper, which is expected to be a helpful reference for future research on superhydrophobic PDMS-based materials for antifouling applications.