Development Of Superhydrophobic Surfaces Research Articles

Enhancing cavitation erosion resistance of VC+TiC coatings with PTFE in marine environments via lasso regression optimization

This research explores the mechanical properties and erosion mechanisms of SS316, VC+TiC, and PTFE coatings to study cavitation erosion resistance. Microhardness analysis revealed that VC+TiC showed the highest resilience due to its hardness, while PTFE, despite lower hardness, displayed potential with formulation adjustments. Lasso Regression models effectively predicted mass loss under various testing conditions, indicating strong relationships between independent variables and erosion responses. Scanning Electron Microscopy (SEM) analysis uncovered distinct erosion mechanisms for each coating, with SS316 showing plastic deformation, VC+TiC exhibiting crater formation, and PTFE displaying torn splats. The development of superhydrophobic surfaces from VC+TiC and PTFE coatings offers promising applications in mitigating cavitation erosion, providing valuable material-specific insights into this phenomenon.

Development of superhydrophobic surface on mild steel by a facile approach and analyzing its self-cleaning and anti-freezing properties

Superhydrophobic surfaces are currently a subject of great interest because of their tremendous applications. This study offers greater insight into the self-cleaning ability and anti-icing behavior of the superhydrophobic mild steel and finds application in aircraft and marine systems. Superhydrophobic surfaces were developed on the mild steel surface by improving the roughness and reducing the energy on the surface. Mild steel was chemically etched with HCL solution for 10 min to improve the roughness. After etching, the surfaces were immersed in stearic acid solution for 3 h by solution immersion method to introduce low surface energy. The resultant surfaces have a combination of nano and micro-roughness. The roughness of the samples was measured with the aid of surface roughness tester. The roughness of the prepared surface is 4.213 μm. The microstructure of the as-prepared surface was characterized by a scanning electron microscope. The surfaces have changed to be pine-cone-like structure. The pinecone-like hierarchical structures can generate numerous grooves in which the air can be trapped which lead to a larger contact angle. The contact angle was measured by using a goniometer setup. The obtained contact angle of the surface is as high as 154° with a lower contact angle hysteresis. The surfaces were tested for self-cleaning and ice-delaying properties. The as-prepared superhydrophobic surfaces can self-clean the surface from dirt/dust while the water droplets roll over the surface. A freezing delay time of 392 s was achieved on the surfaces. The prepared surfaces possess better self-cleaning and ice-delaying properties.

Investigating bio-based solvents as a sustainable alternative in the formulation and fabrication of superhydrophobic surfaces

Organic solvents can be highly toxic to humans, causing damage to the tissues and toxin metabolizing systems. Petroleum-based solvents (such as n-hexane) are likely to trigger endocrine disruption in humans regularly exposed to them. Given this, there is still a high demand for petroleum-based solvents, as they can be used to fabricate materials for various high-performance products. In addition, extensive environmental damage is also caused by petroleum-based solvents. This biological and environmental harm has been the main cause of the demand for sustainable and cost-effective development of environmentally non-hazardous solvent systems. An area targeted to achieve this is bio-based solvent alternatives. In this report, 2-methyltetrahydrofuran (2-MeTHF), a bio-based solvent, is explored as an alternative solvent in the development of superhydrophobic surfaces, replacing n-hexane. This model system explores the factors considered when exploring the implementation of bio-based solvents in the development of highly advanced materials. In this research, both 2-MeTHF/n-hexane are used in the formulation/deposition of superhydrophobic polymer–nanoparticle composites (SPNCs). SPNCs developed using 2-MeTHF have water repelling functionality like those developed using n-hexane, while also demonstrating performance enhancements. Overall, this solvent exchange is aimed to serve as an example of what can be achieved in similar systems to enhance the sustainability of chemical processes that require organic solvents.

Study on Nonfluorinated Preparation and Properties of Superhydrophobic Surface

The preparation of a superhydrophobic surface on metal can improve the self-cleaning, anti-fouling, and anti-bacterial properties of the surface. At present, the superhydrophobicity of the sample surface is mostly obtained by modifying the rough surface with fluorine-containing modifiers, which is unfavorable to the environment. Therefore, developing superhydrophobic surfaces without environmental pollution has become a research hotspot. Based on laser etching technology, the rough surface with a micro-nano dual-scale structure was prepared on aluminum alloy, and then a green and natural saturated fatty acid — myristic acid was used to modify the rough surface. Contact angle measuring instrument, depth of field microscope, scanning electron microscope and Fourier transform infrared spectrometer were used to characterize the wettability, surface morphology, and chemical composition of the modified rough surface (S1). Self-cleaning, anti-contamination, antibacterial, mechanical durability, and thermal stability of the S1 surface were tested experimentally. The wetting of droplets on hydrophobic surface was simulated by using COMSOL Multiphysics software, and a computational model was established to compare different functional structures, so as to understand the influence of parameters on the enhancement of hydrophobic properties of material surface. The results showed that the static contact angle (WCA) of the surface modified by myristic acid reached 152.3[Formula: see text], and the hydrophobic index was −0.808, and the WCA value first increased and then decreased with the change of modification time and concentration. With the increase of myristic acid concentration, the peak value of the contact angle WCA of S1 was negatively correlated with modification time. The self-cleaning rate, anti-stain rate, and antibacterial rate of S1 were 91.4%, 83.6% and 88.4%, respectively, showing excellent self-cleaning, anti-stain, and antibacterial ability. In the mechanical durability test, the S1 surface can resist at least 50 times tape peeling, 30 times steel wool friction and wear, the and 180[Formula: see text]g sand falling impact test still keeps superhydrophobic. In the thermal stability test, the S1 surface remains superhydrophobic after heat treatment at 100–200[Formula: see text]C for 30[Formula: see text]h. In this study, the multifunctional superhydrophobic surface was obtained on aluminum alloy by laser etching technology combined with a green fluorine-free modifier, which provided some meaningful ideas and references for the green preparation of superhydrophobic surfaces and the application and development of superhydrophobic surfaces in biomedical metals.

Development of super-hydrophobic surface using Tio2 to reduce adverse effects of environmental pollutants on buildings

The development of self-cleaning surfaces in recent years has been significant in preserving buildings from environmental contaminants and improving visual durability. Titanium dioxide (or titania), a photocatalyst, is used with cement to improve aesthetic durability and de-pollution properties. Super hydrophilic materials were developed by covering glass, ceramic tiles, or polymers with the semiconducting photocatalyst titanium dioxide (TiO2). Grease, grime, and organic pollutants disintegrate when TiO2 is exposed to light and are simply swept away by water (rain). Ink and vehicle smoke are utilised to evaluate the self-cleaning properties of TiO2-containing concretes, and the oxidation of carbons (COx), gaseous atmospheric pollutants responsible for acid rain and photochemical smog, is explored using nano titanium dioxide. The research allowed for the identification of photo-oxidation mechanisms of stain and COx on TiO2-containing cement, as well as parallels and differences with pure unsupported TiO2. Engineering TiO2 particles with certain crystallite sizes and modifying the photocatalyst electrokinetic properties by changing the overall pKa of the TiO2 surface have both been shown to be efficient approaches for controlling the attractive features of ion-ion correlation forces. The effects on applications in a concrete building, specifically on the exterior surface, to improve overall photocatalytic activity are reviewed. The experimental data on photocatalytic performances measured for regular and nano-coated samples are examined regarding photocatalyst qualities and the effect of cement's chemical environment on titania particles. The research allowed for the identification of photo-oxidation mechanisms of stain and COx on TiO2-containing cement, as well as parallels and differences with pure unsupported TiO2.

Superhydrophobic Surfaces to Combat Bacterial Surface Colonization

AbstractThe recent COVID‐19 pandemic and the accelerating rise of deaths associated with antibiotic‐resistant bacterial strains have highlighted the global health and economic threats caused by the super spreading of pathogens. A major route of transmission for pathogens is via surfaces contaminated by touch or droplets generated via sneezing and coughing. Current surface disinfection strategies are having diminishing efficacy, due to the increasing number of superbugs and the short‐lasting effect of disinfectants resulting in recontamination. New strategies for inhibiting surface‐mediated pathogen transmission are the focus of significant multi‐disciplinary efforts. Among those, the development of superhydrophobic surfaces (SHS) is increasingly regarded as a powerful alternative, or additive, to antimicrobial strategies. SHS provide a neutral/inert interface that can prevent viral and bacterial surface colonization. Here, the use of such water‐repellent coatings are critically reviewed to impede the surface‐mediated transmission of pathogens, addressing the challenges and future directions for their translation into real‐world settings.

Self-healing system of superhydrophobic surfaces inspired from and beyond nature.

Superhydrophobic surfaces show wide prospects in a variety of applications requiring self-cleaning, anti-fog, anti-ice, anti-corrosion and anti-fouling properties, which have attracted the attention of many researchers. However, superhydrophobic surfaces are inevitably affected by chemical corrosion, scratches and wear in practical applications, resulting in the loss of superhydrophobicity. To solve this problem, researchers have developed superhydrophobic surfaces with self-healing properties. In this paper, the research achievements of self-healing superhydrophobic materials in recent years are summarized, and the preparation and repair principle of self-healing superhydrophobic surfaces are introduced from three aspects: surface chemical composition repair, surface roughness repair and double repair. In addition, some multifunctional self-healing superhydrophobic surfaces are introduced, such as conductive, stretchable, antibacterial, etc. Finally, in order to provide a reference for the preparation of widely used long-acting superhydrophobic materials, some existing problems and future development prospects are described in order to attract more researchers' attention and promote the development of this field.

Natural Superhydrophobic Surfaces and Application

Superhydrophobicity refers to the phenomenon that the contact angle of various low surface tension water droplets on the solid surface is greater than 150°. Over the past few years, people have paid more attentions in the superhydrophobic surfaces’ design and application. The superhydrophobic surfaces are meaningful for basic research and various practical applications, such as self-cleaning, drag reduction, lubrication, and more. This paper summarizes the recent advances and developments in superhydrophobic surfaces systematically. Furthermore, in this work, the authors focus on the basic concepts of superhydrophobic surfaces and commonly used synthetic methods. Electrodeposition and electrospinning methods are mainly introduced. Finally, we also discuss the limitations and challenges encountered in the study of superhydrophobicity, mainly with regard to the fact that drag should be reduced to improve energy harvesting efficiency.

Water droplets impact dynamics on laser engineered superhydrophobic ceramic surface

The development of superhydrophobic surfaces is significant due to the industrial applications in various fields, from energy to biomedical implants. The surface morphology and chemistry primarily govern the characteristics of the interface between the water droplet and the surfaces. Herein, a combination of laser patterning and low-pressure technique has been adopted to generate the superhydrophobic TiN surface. The superhydrophobic surface was subjected to wetting property and chemical analysis with respect to the surface geometry. The impact dynamics of water droplets at the laser-patterned superhydrophobic surface have been studied. The droplet impacts result in finger formation at the start of the spreading, and the droplets formed at the tip of fingers detached from the rim during the retraction. The resulting fragmentation favors decreased travel distance and time required for recoiling the water droplets. The fragmentation during the recoiling results from modified hydrodynamics induced by the surface morphology and wetting property. The laser-processed hierarchical surface structures are a potential method to reduce the contact time at the solid-liquid interface.

Recent progress in the development and anti-icing applications of superhydrophobic coatings

Icing is a major concern in various industrial and academic applications. This issue usually affects the operation of various components such as glass windows, wind turbines, and transmission lines. Due to the accumulation of ice, the substrate's performance can be significantly reduced. This is one of the reasons why the development of superhydrophobic surfaces has been focused on mimicking the properties of naturally inspired surfaces. On superhydrophobic surfaces, the droplets of water vapor are pushed away from the substrate before freezing. On the other hand, in porous surfaces, the air pocket is replaced by a liquid-based lubricant film. In this review article, we discuss the latest developments in the field of superhydrophobic development surface technology. The main objective of this paper is to introduce various synthetic routes that are being studied in the development of superhydrophobic surfaces and to cover certain downfalls which are not being researched such as most of the coating methodologies discussed in this paper are very expensive and are not suitable for large scale productions.

Fabrication of superhydrophobic surface with hierarchical structure by thermal imprinting and spraying

Superhydrophobic surfaces have recently attracted considerable attention in industry owing to their high water repellency and self-cleaning property. Many studies on the development of superhydrophobic surfaces have been reported, but the issues of the poor durability and difficulty in forming the desired hierarchical structures remain. Herein, a superhydrophobic surface with a hierarchical micro/nanostructure and good durability was developed on a poly(methyl methacrylate, PMMA) substrate. The micro-scale pillar array was first fabricated on PMMA by thermal imprinting. 1 H,1 H,2 H,2 H-perfluorooctyltriethoxysilane (PFOTES) was used to chemically modify silicon dioxide (SiO2) nanoparticles before developing nanostructure on the micro-scale pillar array. Subsequently, a nanocomposite suspension composed of polyvinylidene fluoride (PVDF) and PFOTES-SiO2 nanoparticles was sprayed on the pillar surface, forming the desired micro/nano hierarchical structure. The effect of the SiO2 nanoparticle size on the surface hydrophobicity was studied in detail. The good superhydrophobicity of the hierarchical surface, with a high contact angle of 163° and low sliding angle of 7°, was related to its high Brunauer-Emmett-Teller specific surface area of 42.43 m2 g−1 and pore volume of 0.35 cm3 g−1. The contaminants on the surface were cleaned easily as the water droplet rolled off, showing good self-cleaning performance. Owing to the binder of PVDF, the nanocomposite coating showed good adhesion to the PMMA substrate. The developed superhydrophobic surface is expected to be widely applied in self-cleaning, anti-fouling, and waterproof fields.

Substrate thermal conductivity-mediated droplet dynamics for condensation heat transfer enhancement on honeycomb-like superhydrophobic surfaces

The efficiency of dropwise condensation heat transfer has been improved significantly by the development of superhydrophobic surfaces, which are usually fabricated by coating a thin superhydrophobic layer on different kinds of substrates (e.g., different metals/alloys). However, the effects of the thermal conductivity of the substrate on condensation heat transfer over such superhydrophobic surfaces remain unclear. In this paper, we investigated experimentally the condensation heat transfer and droplet dynamics on honeycomb-like superhydrophobic (HCLS) surfaces with hierarchical microporous structures, fabricated by an electrochemical method on four metallic substrates with different thermal conductivities, i.e., copper, brass H96, brass H65 and stainless steel SS316. We observed spontaneous droplet jumping on all these HCLS surfaces at a relatively low degree of subcooling. We also demonstrated the interplay between the substrate thermal conductivity and condensation heat transfer performance during the flooding condensation transition (FCT) by numerical simulations. In the jumping-droplet condensation and flooding condensation regimes, the condensation heat flux and heat transfer coefficient were found to be almost unchanged for different substrates. However, the substrate with a higher thermal conductivity leads to a higher condensation heat transfer coefficient as well as a higher droplet departure frequency at moderate degrees of subcooling, indicating the synergistic effect between the substrate thermal conductivity and droplet dynamics during FCT. The substrate thermal conductivity-mediated droplet dynamics enables a way for further enhancing condensation heat transfer on the HCLS surfaces.

Recent Advances and New Discussions on Superhydrophobic Coatings and Admixtures Applied to Cementitious Materials

Increasing the durability of buildings is one of the biggest challenges of the construction industry of the 21st century. The problems concerning durability are usually related to the presence of humidity or to water infiltration in the porous cementitious materials used in buildings. Advances in biomimetics have allowed the development of superhydrophobic surfaces and materials, with contact angles greater than 150°, which are able to repel water and aqueous products. In this context, this work summarizes the recent advances on superhydrophobic coatings and admixtures applied to cementitious materials. Recommendations for the future improvement of such products are made. The synthesis of superhydrophobic coatings generally includes the deposition of a low surface energy material (LSEM), especially fluoroalkylsilanes, on a microroughened surface, which, in cementitious materials, is usually achieved with the help of nanoparticles or micrometric molds. In this sense, variables as the spraying time duration, and the nanoparticles concentration, surface area and average particle size were identified as directly influencing the surface superhydrophobicity. Functionalized nanoparticles can also be introduced in cement matrix during the paste mixing in order to obtain a longer lasting waterproofing effect. In this case, hybrid nanosilica may react with Ca(OH)2 through pozzolanic reaction. The C-S-H formed may incorporate the organic group of hybrid nanosilica, and might present superhydrophobicity as well, modifying the composite’s microstructure. Besides, the cost of fabricating hydrophobic materials is decisive for their market entry. Hence, the partial or total replacement of fluoroalkylsilanes with less expensive LSEMs seems promising and needs to be further explored.

Molecular Architectonics‐Guided Fabrication of Superhydrophobic and Self‐Cleaning Materials

AbstractSelf‐cleaning surface coatings is ubiquitous with variety of products today including glass and ceramic tiles, anti‐fogging mirrors, paints, mortars, and concrete. The phenomenon of self‐cleaning is attributed to superhydrophobic surface capable of cleaning itself without any human intervention. The development of superhydrophobic surfaces has been inspired by the desire to mimic the nature viz., water repellent property of lotus leaves and the process is termed as lotus effect. A variety of chemical and physical methods have been reported to fabricate of rough surfaces with low‐surface‐energy coating like, molecular assembly processes, chemical vapor deposition, sol–gel method, and breath‐figure technique (BFT) among others. Among them, BFT offers simple solution processability, robustness, and excellent tunability of surface architecture at different length scales. In this progress report, molecular architectonics of small functional molecules and its application in fabricating selfcleaning materials and surfaces through simple solution processing techniques is described. In these bioinspired approaches, self‐assembly properties of small functional molecules at the molecular level can be controlled by conjugating with basic biomolecules or biomimetic units as functional auxiliaries and adapting suitable experimental techniques. Overall, this progress report demonstrates the progress in molecular architectonics‐based approaches to develop superhydrophobic surfaces with self‐cleaning applications.

Development of Superhydrophobic Surfaces via Isotropic Etching and Plasma Sputter Deposition

Development of Superhydrophobic Surfaces via Isotropic Etching and Plasma Sputter Deposition

Effect of repeated immersions and contamination on plastron stability in superhydrophobic surfaces

Development of superhydrophobic surfaces is of great interest for drag-reducing applications as air layers retained underwater greatly reduce fluidic drag. However, liquid flow over these surfaces can result in the collapse of the lubricating air layer. Here, we investigate the dynamic stability of retained air layers on three different superhydrophobic surfaces against repeated immersion and motion through various viscous liquids. The three surfaces investigated are a highly ordered polytetrafluoroethylene micropillar array, a two-level hierarchical random polycarbonate nanofur, and a double-scale hierarchical Teflon AF wrinkled surface. Both repeated immersions and contamination by viscous liquids accelerated the rate of plastron decay on the pillar array and the nanofur, while the Teflon wrinkles remained dry. Five topographical features were identified as correlated to a dynamically stable retained air layer, and a relation between these stability-enhancing parameters and the drag-reducing capabilities is found. Furthermore, resistance of superhydrophobic surfaces against contamination is studied and the directionality of the Cassie-to-Wenzel wetting transition on air-retaining surfaces is demonstrated. Together, an understanding of these properties allows for the rational design of new superhydrophobic surfaces fit for application.

Improved Hydrophobicity of Silicon Dioxide Integrated Zinc-Tellurite Glass Surface

Economically viable and maintenance free glass surfaces with improved hydrophobicity are highly demanding in the recent nanotechnology era. Deposition of pollutants and dirt on glass surface that not only causes visual obscurity but also damages the cultural heritages are still to be researched intensely. It is documented that excellent hydrophobic surfaces (with contact angle greater than 90o) can be achieved by controlling the surface wettability, where liquid droplets remain spherical on such surfaces. Selection of materials and the preparation method play a significant role towards such accomplishments. Stirred by this idea, we explored the feasibility of fabricating super-hydrophobic tellurite glass systems by facilely varying the compositions of different constituents. Highly transparent and thermally stable ternary tellurite glass system with chemical composition of (80-x)TeO2 – xSiO2 – 20ZnO, where x = 0.00 to 0.20 mol% are synthesized via conventional melt-quenching method. Samples are characterized using Atomic Force Microscopy (AFM) and contact angle measurements. The impact of SiO2 concentrations variation on the surface roughness, surface energy, and hydrophobic properties are inspected. Glass surface roughness as much as 9.885 nm is attained. The optimal value of water contact angle is discerned to be 101.02° for 0.1 mol% of SiO2 incorporation into the amorphous tellurite host matrix. Besides, the surface energy revealed an inverse proportionality to the water contact angle. This achieved contact angle (greater than 90°) makes this hydrophobic glass surface beneficial for diverse applications. It is established that the present glass composition may be prospective for the development of super-hydrophobic surfaces.

Development of super-hydrophobic surface on Al 6061 by anodizing and the evaluation of its corrosion behavior

In the present work, super-hydrophobic surface on 6061 aluminum alloy (Al) was fabricated by single-step anodizing and modified by low surface energy materials. This process is a straightforward method which can also be applied at large scales. The effect of anodizing voltage changes on the surface morphology and the wettability of surfaces was also investigated. The uniform roughness on anodic aluminum oxide (AAO) which was fabricated by single-step anodizing and chemically modified by stearic acid (STA) had super-hydrophobic properties. The treatment before and after anodizing process played a significant role in bonding STA onto AAO surfaces. According to the contact angle obtained from AAO and anodic aluminum oxide modified by STA, which were less than 20° and 152±0.3°, respectively, their wettability and surface energy were examined. Moreover, the corrosion resistance of the super-hydrophobic surface was tested by Tafel polarization and electrochemical impedance spectroscopy (EIS) tests. The results showed that the inhibition efficiency (η) of AAO surface compared to super-hydrophobic surface increased from 58% to 97% which is an indication of excellent corrosion resistance of these coatings.

Development of Superhydrophobic Surface for Medical Textiles

Development of Superhydrophobic Surface for Medical Textiles

Development of Superhydrophobic Surface for Medical Textiles

The objective of this study was to fabricate superhydrophobic surface with superhydrophobic property using nanoparticles and water-repellent agents for medical textiles. The wettability of the super hydrophobic surface was compared to that of other materials having a variety of roughness and surface energy. Microstructures were fabricated with 100% PET textiles having various yarn thickness and yarn finishing. Nano-sized structures were fabricated by finishing the PET textiles with CNTs nanoparticles using water-repellent agent. Contact angle (CA), contact angle hysteresis and shedding angle analysis were evaluated by Theta Lite contact angle meter (attension, Finland). Also, breathable waterproof properties were measured by water vapor transmission rate (ASTM 96-CaCl2) and air permeability (ISO 9237-1995). The results indicate that the super hydrophobicity was strongly influenced by the binary structure having nano-scaled roughness than by the chemical composition of surface. It was proven that the shedding angle, the angle at which a water droplet rolls off the surface, was reasonable method to analysis the super hydrophobic properties. Also, it was shown that all of the water-repellent agents and nano-particles did not decrease air permeability and water vapor transmission rate noticeably. The DTY sample treated with CNTs exhibited the highest super hydrophobic properties, having static contact angle of 160° and shedding angle of 4.4°. These results indicated that the long nanofiber shape of carbon nano tubes successfully maintained the trapped micro sized air layers like a papillae of lotus leaf.