Superhydrophobic Nanocomposite Coatings Research Articles

Formation of Highly Robust Superhydrophobic Nanocomposite Coatings via Dual Spraying Technique

The development of materials that repel water, known as superhydrophobic materials, has been hindered by their vulnerability to mechanical abrasion. This issue is particularly pronounced for superhydrophobic nanocomposite coatings fabricated using a simple blend of resin and nanoparticles (NPs) through uncomplicated methods such as spraying or brushing, where an excessive amount of NPs can deteriorate the mechanical property. Moreover, the limitation of thickness puts forward a request for a high retention rate of the coatings. In response to these challenges, this study presents an innovative approach aimed at enhancing the robustness of superhydrophobic nanocomposite coatings through the utilization of a straightforward dual spraying technique. The results demonstrate that the particles with hierarchical micro/nanostructures fabricated by the primary spraying process provide abundant roughness feedstocks for the secondary‐sprayed coatings, in which superhydrophobicity properties can be achieved with less NP content. Additionally, the mechanical durability of the coatings can be reinforced by the addition of appropriate amounts of aluminum oxide (Al2O3) NPs and the continuous‐distributed particles fabricated by the primary‐spraying process, exhibiting a longer abrasion distance and a higher retention rate. Also, the prepared sample shows comprehensive robustness in adhesion, abrasion, and dynamic impact tests. By offering insights into material selection and process optimization, this study paves the way for creating resilient superhydrophobic coatings using a streamlined and convenient approach.

Dry abrasion mechanisms of superhydrophobic nanocomposite coating surfaces

To date, the theoretical studies on dry abrasion on surfaces with microscopic roughness are based on JKR or DMT contact theory. Superhydrophobic nanocomposite coatings with low surface energy and microscopic surface roughness have extremely low real contact area and adhesion to the abrasive when subjected to contact and friction, making the above theories inapplicable. To date, there lack of theoretical studies on the dry abrasion characteristics of superhydrophobic nanocomposite coating surfaces. In response to this problem, a numerical understanding of the frictional force on superhydrophobic nanocomposite coatings is proposed based on Hertz contact theory, and the abrasion mechanisms of superhydrophobic nanocomposite coatings and its influencing factors are analyzed from the perspective of microscopic torque balance. The abrasion process is divided into three stages, and there exists a minimum value of bonding strength between the microstructure on the coating surface and the polymer matrix of the coating that determines whether abrasion will occur. This minimum bonding force is determined by Young's modulus of the polymer matrix, the radius of the microstructure, and the applied load. The conclusions can be a guide for the improvement of the anti-dry-abrasion property of superhydrophobic nanocomposite coatings from the perspective of coating preparation.

Study of nano-ZnO improvement of the mechanical properties and corrosion resistance of modified-SiO2/PTFE superhydrophobic nanocomposite coatings by one-step spraying

A rapid and low-cost method to prepare a superhydrophobic coating with good mechanical stability, self-cleaning, and excellent corrosion resistance.

D-Cysteine Functionalized Superhydrophobic Nanocomposite Coating with Multiple-Action Antibacterial Property and Enhanced Mechanical Durability

In this study, a durable superhydrophobic antibacterial coating was developed by a facile spraying method. A mixture of bisphenol A diglycidyl ether (BADGE) and hydrophobic SiO2 nanoparticles was sprayed on carbon steel to provide a superhydrophobic substrate. D-cysteine (D-cys) functionalized SiO2/dopamine/silver nanoparticles with multilayer core-shell structure were then sprayed on superhydrophobic substrate to enhance antibacterial performance. The results of morphology observation and X-ray photoelectron spectroscopy (XPS) indicated the successful preparation of antibacterial nanoparticles and presented the hierarchical micro/nanostructures of coating surface. The as-prepared coating exhibited superhydrophobicity, with the water contact angle of ~153°. The coating was endowed with good mechanical durability, which maintained the water contact angle of ~150° after 180 cycles in tape-peel tests. The results of electrochemical impedance spectroscopy showed satisfactory corrosion resistance of this coating during 3 days of immersion in 3.5% NaCl solution. Furthermore, the coating showed excellent antibacterial performances against Escherichia coli and Pseudomonas aeruginosa, which benefited from the synergistic actions of low wettability of superhydrophobic surface, bactericidal behavior of Ag nanoparticles, and biofilm inhibition effect of D-cys.

Superhydrophobic nanocomposite coatings for electrical insulators

Superhydrophobic nanocomposite coatings for electrical insulators

Superhydrophobic nanocomposite coatings based on different polysiloxane matrices designed for electrical insulators

The present paper describes for the first time the influence of three different kinds of polysiloxane as hydrophobic agent on superhydrophobic coatings for electrical insulators: a trimethoxy (2,2,4-trimethyl pentyl)-based silane; a mixture of methyl methoxy siloxane with methylsilsesquioxane; a mixture of dimethyl siloxane, methylsilsesquioxanes and n-octyl silsesquioxanes. The polysiloxane properties were investigated by thermogravimetric (TGA) and hydrophobic (contact and sliding angles) analysis, indicating great differences on thermal properties and surface free energy. The polysiloxane binders were loaded with different sizes of microsized alumina trihydrate (ATH) and organophilic nanosilica functionalized with octyl-silane and polydimethylsiloxane (PDMS). The hydrophobicity of the coating was evaluated by water contact angle (WCA) and sliding angle (SA). The morphology and roughness of the coatings were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Moreover the superhydrophobic durability of the coatings was evaluated by water immersion, hydrophobicity recovery, hydrophobicity transfer and adhesion. The effectiveness of these materials as coatings for glass electrical insulator was evaluated by tracking and erosion resistance using the inclined plane test (IPT). The results showed that the polysiloxane based on a mixture of methyl methoxy siloxane with methylsilsesquioxanee loaded with ATH and PDMS-treated silica exhibited the most promising characteristics as high contact angle, self-cleaning ability, good adhesion to the substrate and low number of leakage current peaks during the tracking and erosion resistance test. Such characteristics can bring benefits on electrical insulators like reducing the formation of conductive surface paths and the consequent degradation of the coating by dry band arcs, increasing its resistance when exposed to the electric field.

Effects of chemical composition on the hydrophobicity and antifouling performance of epoxy-based self-stratifying nanocomposite coatings

Inspired by nature, the superhydrophobic surface has great potential for application in the field of antifouling due to its excellent fouling resistance. Nanocomposite coatings are an economical way to fabricate superhydrophobic surfaces by controlling the surface chemical composition and topography. However, the available open literature assessing the chemical composition effects on hydrophobicity and antifouling performance is rare. In this study, epoxy-based nanocomposite coatings with various wettability were fabricated by using the air-spray technique. The element distributions of the coatings at different depths were characterised by EDS and XPS. The results showed that the top coating surfaces of ER-F, ZnF40-1:5, and ZnF40-1:9 were enriched in F and Si elements, evidencing the self-stratifying. And by reducing the solid surface free energy, the hydrophobicity of ER-F, ZnF40-1:5, and ZnF40-1:9 was significantly improved. And the coating ZnF40-1:9 achieved super-hydrophobic. Based on the Young's equation and the “equation of state for the interfacial tensions”, it was found that the effect of solid surface free energy on CAH was greater than that on WCA due to the greater coefficient of the variable. The superhydrophobic coating ZnF40-1:9 shows great antifouling performance against marine diatom P. tricornutum and its antifouling rate is up to 94.1%. By reducing the surface free energy, the hydrophobicity of nanocomposite coatings can be improved significantly, consequently improving the antifouling performance effectively. These findings might provide insight into developing superhydrophobic nanocomposite coatings to inhibit biofouling.

Surface topography effects on the wettability and antifouling performance of nano-ZnO epoxy composite coatings

Nature-inspired eco-friendly superhydrophobic surfaces have attracted great interests from fundamental research to antifouling application. Nanocomposite coatings are an economical way to fabricate superhydrophobic surfaces. This paper studies how the coating topography can be controlled by using different nanoparticle sizes and concentrations. Six three-dimensional surface parameters are used to define the resulting topography and explore the correlations with wettability. Three unique scenarios are proposed based on the relationship between the two key parameters core void volume (Vvc) and core material volume (Vmc) to assess the relationship between surface roughness and solid-liquid contact area fraction (f). A water contact angle (WCA) of 152.6° and contact angle hysteresis (CAH) of 2.9° are obtained by employing dual-sized nanoparticles at 45% nanoparticle concentration (wt./wt.), which is up to 10% less than the superhydrophobic coating fabricated by using single-sized nanoparticles (30 nm). Furthermore, Vvc and peak sharpness dominate f, consequently dominating the wettability in the transitional state and Cassie state, respectively. The antifouling tests using Phaeodactylum tricornutum and Bacillus sp. show a negative correlation between f and antifouling performance, and the minimum adhesion ratios are only 0.41% and 0.53%, respectively. The superhydrophobic surfaces with Vvc/Vmc > 1 are shown to be better for antifouling applications. These findings are important for designing superhydrophobic nanocomposite coatings for antifouling performance.

Preparation of New Polymer Nanocomposites and Analysis of Their Superhydrophobic Properties

As an important branch of the superhydrophobic research field, polymer/nano composite superhydrophobic materials have broad application prospects in anticorrosion, self-cleaning and oil-water separation. In this paper, a polymer-based nanocomposite superhydrophobic coating was prepared by a simple method, and its microscopic morphology, wettability and other related properties were characterized and analyzed. The SiO2/PS and SiO2/PVC superhydrophobic nanocomposite coatings were prepared by spin coating. The method is simple, easy to implement, low in cost, and does not require special equipment and harsh conditions. The addition of hydrophobic nano-silica reduces the surface energy of the coating while increasing the surface roughness, without the use of low surface energy substances. The coating exhibits excellent acid and alkali corrosion resistance, and is suitable for a variety of substrates. It can be used as an anticorrosive coating for metal protection and has a good application prospect.

Fluorine-Free Transparent Superhydrophobic Nanocomposite Coatings from Mesoporous Silica

In recent decades, there has been a growing interest in the development of functional, fluorine-free superhydrophobic surfaces with improved adhesion for better applicability into real-world problems. Here, we compare two different methods, spin coating and aerosol-assisted chemical vapor deposition (AACVD), for the synthesis of transparent fluorine-free superhydrophobic coatings. The material was made from a nanocomposite of (3-aminopropyl)triethoxysilane (APTES) functional mesoporous silica nanoparticles and titanium cross-linked polydimethylsiloxane with particle concentrations between 9 to 50 wt %. The silane that was used to lower the surface energy consisted of a long hydrocarbon chain without fluorine groups to reduce the environmental impact of the composite coating. Both spin coating and AACVD resulted in the formation of superhydrophobic surfaces with advancing contact angles up to 168°, a hysteresis of 3°, and a transparency of 90% at 550 nm. AACVD has proven to produce more uniform coatings with concentrations as low as 9 wt %, reaching superhydrophobicity. The metal oxide cross-linking improves the adhesion of the coating to the glass. Overall, AACVD was the more optimal method to prepare superhydrophobic coatings compared to spin coating due to higher contact angles, adhesion, and scalability of the fabrication process.

Влияние среды на защитную эффективность супергидрофобных нанокомпозитных покрытий на углеродистой стали

Новые технологии, Химическая промышленность, Химическая технология, Научные журналы, Защита от коррозии, Технология металлов, Свойства материалов, Технические журналы, Наука и технологии, Справочная литература, Научные разработки

Superhydrophobic Nanocomposite Coatings of Hydrophobic Silica NPs and Poly(methyl methacrylate) with Notable Self‐Cleaning Ability

AbstractThe present paper describes a facile and inexpensive dip coating method for preparation of hierarchical superhydrophobic nanocomposite coating. The hydrophobic silica nanoparticles (NPs) are synthesized via sol–gel technique. The superhydrophobicity of the coating is controlled by adjusting the concentration of silica NPs in poly (methyl methacrylate) (PMMA). After optimization, the coating exhibited water contact angle of 165° and sliding angle of 4°. The surface morphology of the superhydrophobic coatings revealed hierarchical rough structure formed on the glass substrate, which enable air trapping. The prepared superhydrophobic coating showed wetting stability under water jet impact with notable self‐cleaning performance. The mechanical stability of the superhydrophobic coating is studied using sandpaper abrasion and adhesive tape peeling test. Such highly non‐wettable and self‐cleaning coatings have potential in various practical applications.

Scalable-Manufactured Superhydrophobic Multilayer Nanocomposite Coating with Mechanochemical Robustness and High-Temperature Endurance.

Artificial superhydrophobic coatings with mechanical stability, chemical stability, and strong adhesion have been achieved separately. However, a simultaneous demonstration of these features along with stability to high-temperature exposure is challenging. Herein, inspired by the micro/nanoscale hierarchical superhydrophobic surfaces of solid cactus plants, we propose a novel plasma-enhanced high temperature liquid-phase-assisted oxidation and crosslinking (PHLOC) in-situ co-growth strategy to design superhydrophobic nanocomposite coatings on metals based on organic-inorganic multilayer structures in which PTFE nanoparticles cross-linked to form a compact top layer with hierarchical surface textures on a ceramic skeleton with a papilla array, integrating multiple robust wettability characteristics with mechanochemical strength to isolate the underlying materials from the external environment. Remarkably, the superhydrophobic coating exhibits strong mechanical robustness undergoing the 120th linear abrasion or 40th rotary abrasion cycle and can be applied on large area and arbitrary shapes of metal substrates. Moreover, the samples sustain exposure to highly corrosive media, namely, aqua regia, sodium hydroxide solutions, and simulated seawater solution, to reflect long-term chemical robustness. More importantly, the multilayer coating demonstrates excellent high-temperature endurance, thermal cycling stability of 500 °C, and thermal repairability of superhydrophobicity. With multifaceted robustness and scalability, the superhydrophobic multilayer coating should find potential usage in the field of high-tech equipment with severe alternating or impact loads, high-temperature service, and chemical corrosion.

Facile fabrication of durable superhydrophobic SiO2/polyacrylate composite coatings with low nanoparticle filling

This study aimed to prepare superhydrophobic coatings that could be used for practical applications. Nanocomposites of polyacrylate containing silica nanoparticles were prepared by dispersing silica sol in a polyacrylate solution. Superhydrophobicity was attainable for nanocomposite coatings with a filler percentage of only 15 wt%. Reducing the loading of silica nanoparticles not only minimized the costs but also simplified the preparation. The superhydrophobic coatings with water contact angle as high as 155.4° and contact angle hysteresis of 5.6° exhibited good self-cleaning property. The superhydrophobic nanocomposite coatings also displayed good mechanical properties and excellent thermal stabilities that favor indoor and outdoor applications. The superhydrophobic nanocomposite coatings can be used on various substrate surfaces, including glass plates, polymethyl methacrylate plates, polycarbonate plates, and aluminum sheets. Given their large-scale and low-cost fabrication, superhydrophobic coatings show great promise in practical applications in a broad range of fields.

High durability of non-fluorinated superhydrophobic nanocomposite coatings

In the present work, we developed eco-friendly and cost-effective nanocomposite coatings. These wax-derived coatings showed high superhydrophobicity while exhibiting mechanical and thermal robustness. The addition of nano-alumina particles in wax (Beeswax and Paraffin) significantly enhanced de-wetting (contact angle ~ 156°) with extremely low hysteresis (<5°). The Paraffin-based composite coating showed better thermal (up to 50 °C) and mechanical (Δθ≈5°) (droplet impacts) stability than Beeswax counterpart, while also sustaining outdoor exposure. The superhydrophobic coatings showed self-cleaning ability with significantly low water consumption (<1 μl/mm2). We showed that nanocomposite-wax coatings possess required durability and are potential candidates for developing non-fluorinated self-cleaning surfaces.

Highly UV and Corrosion - Resistant Poly(vinylidene fluoride)‐Co‐Hexafluoropropylene - Carbon Nanotubes Superhydrophobic Nanocomposite Coating for C-Steel

A robust superhydrophobic nanocomposite coating (PVDFHFP-CNTs) of poly(vinylidene fluoride)‐co‐hexafluoropropylene (PVDFHFP) and carbon nanotubes (CNTs) was fabricated on carbon steel using a two-step process: electrospinning and spray coating. The wettability properties of the prepared coating were inspected by measuring the water contact angle (WCA). Before the addition of CNTs, the WCA and the sliding angle (SA) of the PVDFHFP were 150°±3 and 2°±3, respectively while after the addition of CNTs, their values increased to 155°±2 and 3°±2, respectively. The wettability of the as-prepared coatings was also inspected after exposure to UV radiation with a light power of 0.89 W m-2 for 41 cycles according to ASTM standard D4587 – 11 (general metal coatings Standard) whereas each cycle includes 8 h exposure to UV illumination at 60 °C, and condensation for 4 h at 50 °C. It was found that the measured WCA and water contact water angle hysteresis (WCAH) for PVDFHFP-CNTs nanocomposite 152° ± 2 and 6° ± 2 compared to 147° ± 2 and 17° ± 3 of pure PVDFHFP, respectively. The morphology of the superhydrophobic coating was explored. It shows a beaded-like fiber structure. Spectra elements of the prepared coatings were obtained using the Fourier transform infrared instrument (FTIR). The surface roughness of the fabricated super water-repellent coatings were measured using atomic force microscope (AFM). The electrochemical behavior of superhydrophobic coating was evaluated by electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl before and after exposure to UV radiation. The outcomes showed the high corrosion resistance of PVDFHFP-CNTs compared to the neat PVDFHFP coating in presence and absence of UV.

Superhydrophobic nanocomposite coatings of poly(methyl methacrylate) and stearic acid grafted CuO nanoparticles with photocatalytic activity

Herein, the applicability of a convenient approach for the fabrication of nanocomposite coatings of poly(methyl methacrylate) (PMMA) layers containing as-synthesized or stearic acid-modified CuO nanoparticles through spray coating of a textile surface is reported. The synthesized CuO nanoparticles had an average particle size of 90 nm. PMMA polymer was prepared with a molar mass of 60,000 g/mol and a polydispersity index of 1.6. The nanocomposite coatings and their components were characterized using several techniques including XRD, ATR-FTIR, SEM, EDX, TGA, GPC, UV–vis, DLS, and WCA measurements. The optimum nanocomposite coating (with a CuO/PMMA ratio of 5:1 and prepared from the modified CuO nanoparticles) presented the high water contact angle of 161° and the low sliding angle of 2°, thus demonstrating the superhydrophobic and self-cleaning properties of the surface. Moreover, the textile sample coated with the nanocomposite layer of the original CuO nanoparticles and PMMA presented faster photodegradation of rhodamine B as a model compound relative to the above-mentioned coating. An nth order power-law kinetic equation fit perfectly to the experimental data for the nanocomposite coatings of PMMA in combination with the modified and pure CuO nanoparticles.

Development of Superhydrophobic Nanocomposite Coatings on FRP Sheet Surface for Anti-Icing and Wear-Resistance Applications

The main aim of this research work is to develop a multi walled carbo nanotubes and carbon nano fibers in a superhydrophobic manner.It is developed in the form of a carbon composite. The work is coated by including a water contact angle 158.2° and also with an inclined angle of 5.2°. The advanced processing technique is utilized in this work.In this the combimation of supercritical fluid processing is done.The supercooled water experiment (SWT) displayed that the surface of composite coating wettability is a major controlling section for decreasing ice accretion on the stable surface. Based on the observations it can be identified that both the carbon nao tubes and multi walled carbon nano tubes had a very good wear resistant.Moreover, the ~120 S duration of rubbing the inclusion of trapped wear fibers and matrix increase the friction of force because of strong adsorption and the resulting composites have strong mechanical transduction compared with CNF and MWCNT coating. These results show that a coating strategy is very effective for anti-icing system and it s attributed to the the impending value in certain application where maximum scale is required.

Superhydrophobic nanocomposite coatings with photoinitiated three-dimensional networks based on reactive graphene nanosheet-induced self-wrinkling patterned surfaces

HypothesisBionic superhydrophobicity including high contact angle, low sliding angle and nonstick property, combined with both strong pH and ultraviolet (UV) resistance, is difficult to simultaneously achieve for large-scale preparation of superhydrophobic surfaces by blending polymer with a nonreactive inorganic nanofiller. ExperimentsA series of high pH and UV-irradiation-resistant superhydrophobic nanocomposite films were prepared through UV-light-assisted chemical cross-linking among ternary components under nitrogen protection. Ethoxylated bisphenol A diacrylate, 2-(perfluorooctyl) ethyl acrylate, reactive thiol-coupled graphene nanosheets and photoinitiator were evenly mixed, followed by UV-irradiation curing. FindingsAbundant 3D networks could be formed. A robust self-wrinkling surface morphology was formed due to a UV-curing-induced inner tension in the composites, 2D morphology-induced flexibility for graphene nanosheets and fluorine-bearing component-induced phase separation at the wetted surfaces. High roughness and use of the fluorine element endows the surfaces with superhydrophobicity and oleophobicity. A favorable nonstick performance was obtained. Superhydrophobicity could be maintained despite changing the film-forming substrate, pH of soaking solutions from 1 to 12, or use of a prolonged UV-irradiation time reaching 120 h. Therefore, both superhydrophobicity/oleophobicity and strong pH/UV resistance are finely balanced. This work might open up the way for large-scale fabrication of promising superhydrophobic surfaces.

Anticorrosion coating for magnesium alloys: electrospun superhydrophobic polystyrene/SiO 2 composite bers

Superhydrophobic nanocomposite coatings for magnesium surfaces with remarkable corrosion resistance were fabricated by electrospinning in the presence of fluorosilane-functionalized silica (SiO$_{2})$ nanoparticles. The effects of surface-modified silica (mod-SiO$_{2})$ nanoparticles on the superhydrophobicity and corrosion resistance of polystyrene (PS)/mod-SiO$_{2}$ fiber coatings were evaluated. The incorporation of the SiO$_{2}$ nanoparticles endows PS fibers with rough surfaces exhibiting a water contact angle (WCA) of 165$^{\circ}$. The surface wettability, corrosion resistance, and their relation to the inorganic content in the PS fibers and the contact angle of the composite coatings were explored. Analysis of the corrosion results confirmed that the PS/mod-SiO$_{2}$ coating protected the Mg surface from corrosion. In addition, PS fibers containing mod-SiO$_{2}$ nanoparticles showed improved hydrophobicity, and excellent corrosion resistance was achieved with PS fibers containing 4 wt% SiO$_{2}$ nanoparticles.