Fabrication Of Superhydrophobic Surfaces Research Articles

Investigation of wetting properties of gold nanolayer coated aluminum surfaces textured with continuous-wave fiber laser ablation

This paper describes the fabrication of superhydrophobic surfaces on aluminum plates coated with 15 or 40 nm gold nanolayers by a continuous-wave fiber laser ablation in ethanol. Laser ablation resulted in the creation of Al2O3 microstructures combined with Au micro/nanoparticles on the Al surface. Significant structural evolutions such as reduction of micro/nanostructure size and the percentage of the oxygen concentration were observed on the surfaces by increasing the thickness of the Au nanolayer. In addition, the fabricated Au and Al2O3 nanoparticles separated from the Al surface were non-spherical and roughly spherical in shapes, respectively. The static water contact angle technique to the evolution of wetting properties was employed. The laser-ablated Al sample with a 40 nm Au layer demonstrated a near superhydrophobic surface with a water contact angle of 152 ± 2°. The results of the various characterizations showed that the surface topography was the dominant factor in specifying the degree of hydrophobicity.

Robust superhydrophobic surface fabrication by fluorine-free method on filter paper for oil/water separation

Robust superhydrophobic surface exhibiting anti-fouling and self-cleaning ability were successfully fabricated by nano TiO2 modified by γ-aminopropyltriethoxysilane (KH550) and polydimethylsiloxane (PDMS) via wire rod coating. Due to the lower surface energy of PDMS and the hierarchical structure caused by the different aggregation sizes of TiO2 nanoparticles, the contact angle of the resulting superhydrophobic coating was 154.5° and the rolling angle was 3.5°. And the coated paper still had good non-wettability under water immersion. In addition, the coated paper was tolerant to mechanical damage and various temperature conditions. Even after 40 sandpaper wear cycles, the coating can still maintain good mechanical stability and superhydrophobicity. The superhydrophobic paper was used for oil-water separation, the separation efficiency was about 98% even after used 10 times. Furthermore, the prepared superhydrophobic paper exhibited excellent self-cleaning and anti-fouling properties, as well as demonstrated superb resistance to various water solutions owing to its high hydrophobicity. Moreover, the prepared superhydrophobic paper has application prospects in the industry of special wetting materials.

Fabrication of biomimetic superhydrophobic and anti-icing Ti6Al4V alloy surfaces by direct laser interference lithography and hydrothermal treatment

Nature gives us a large number of inspirations in designing functional materials. Many plant leaves with self-cleaning properties are ubiquitous in nature. These plants have hierarchical structures, which have extreme repellency to liquids and have considerable technical potential in various applications. Herein, we present a method for fabricating bionic taro leaf surfaces by direct laser interference lithography (DLIL) and hydrothermal treatment. The micro-pillar array structure (MPA) was fabricated by DLIL, and a layer of nano-grass structure (NG) was grown on it by hydrothermal treatment. Experiments indicate that the hierarchical composite structures not only have a satisfactory superhydrophobic function with the apparent contact angle (CA) of 172° and sliding angle (SA) of 4°, but also have a strong anti-icing ability with the delay time (DT) of 3723 s. The method is simple and high-efficient for fabricating bionic self-cleaning and anti-icing surfaces.

Laser-chemical treated superhydrophobic surface as a barrier to marine atmospheric corrosion

A time efficient and cost-effective laser-based surface texturing technique combining nanosecond laser ablation and chemical immersion treatment was developed for steel alloy to achieve enhanced corrosion resistance in marine atmospheric environment. Three different surface patterns were created by nanosecond laser ablation and the laser patterned samples were subsequently immersed in 1H,1H,2H,2H-perfluorooctyl silane (FOTS) solution to tune surface chemistry. Dual-scale surface structure was formulated on the laser-chemical treated surface, as confirmed by the scanning electron microscopy (SEM) and confocal laser scanning microscope analyses. X-ray photoelectron spectroscopy (XPS) analysis was conducted to validate that desired surface chemistry was achieved on the laser-chemical treated surface. The effect of surface pattern on several key surface functionalities, including surface wettability, corrosion resistance and chemical stability was systematically presented in this work. Firstly, it was demonstrated via wettability measurements that the laser-chemical treated surface achieved superhydrophobicity with a water contact angle of 158.9°. Secondly, electrochemical and NaCl deliquescence tests were conducted to determine the corrosion resistance of the laser-chemical treated surfaces in marine atmospheric environments. It was confirmed that the laser-chemical treated surface can prevent marine atmospheric corrosion induced by salt deliquescence. Furthermore, it was revealed by electrochemical test that the laser-chemical treated superhydrophobic surface exhibited distinctly better anti-corrosion performance. The experimental results showed that the corrosion rate for the laser-chemical treated surface with microgroove pattern is approximately 5.4% of the corrosion rate for the untreated surface, indicating significant improvement of corrosion resistance for the laser-chemical treated surface. Thirdly, the high water contact angle of 151.0° sustained on the laser-chemical treated surface after electrochemical tests helped confirm the improvement of its chemical stability in corrosion medium. These experimental findings clearly demonstrate the developed nanosecond laser-chemical treatment method can be very effective for fabrication of stable superhydrophobic metal surface as a barrier to marine atmospheric corrosion with enhanced corrosion resistance.

Nanosecond laser fabrication of superhydrophobic surface on 316L stainless steel and corrosion protection application

Herein, we developed an facile, cost-effective and efficient method to fabricate microstructures of different scales on 316 L stainless steel substrate surface by laser modification. By changing the laser parameters, such as various laser fluence (2.69, 3.96, 6.28, 8.14,9.55 J/cm2) during laser irradiation, different sizes of micro-cracks and brain-like microstructures can be obtained. The experimental results indicate that a static contact angle of 160 ± 5° and the sliding angle of 3 ± 0.5°, can be achieved at a scanning interval of 30.0 μm and laser fluence of 8.14 J/cm2, which has the best outstanding wettability. In addition, the microstructures and chemical compositions on the surface were examined by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The corresponding corrosion resistance properties was evaluated by the means of potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). The laser textured superhydrophobic surface was found to enhance the corrosion resistance dramatically. Also, after the laser modification, excellent self-cleaning performance was demonstrated based on tests with quartz sand particles. Particularly, we extensively discussed how the structures on the 316 L stainless steel were formed after the ultraviolet nanosecond laser irradiation and the interaction mechanism of the laser and substrate. This study not only provides important insights into the formation mechanism of laser textured surfaces, but also guides practical industrial applications as this approach is simple, low-cost and convenient for fabrication of large-area superhydrophobic surfaces on various metal materials.

Fabrication of durable superhydrophobic surface through silica-dissolution-assisted etching template approach

ABSTRACT A convenient fabrication approach is proposed for a durable superhydrophobic epoxy surface. By duplicating micro-rough topography of the template, covalently grafting with TiO2 nanoparticles, and treating with perfluorooctyltriethoxysilane, the surface shows superhydrophobicity with a high static contact angle (162.0°) and a low sliding angle (2.5°), respectively. And its WCA has hardly changed along with the pH value of solutions. Besides, the superhydrophobic property remains constant even after 144 h long-term UV radiation or 16 cycles of friction tests. The surface also exhibits superior self-cleaning resilience for organic contaminants of oleic acid, kerosene, lubricants, and vegetable oil by TiO2 photocatalysis degradation of pollution.

One-step fabrication of flexible superhydrophobic surfaces to enhance water repellency

This paper investigates a one-step fabrication method of flexible superhydrophobic surfaces on silicone rubber substrates, which enhance the repellency to both static and impacting water droplets. Grooved structures with hierarchical roughness were constructed directly on intrinsically hydrophobic silicone rubber surfaces using nanosecond ultraviolet laser. The effects of laser parameters, laser scanning speed and number of scans, on surface morphology and wettability were explored. Results show that the scanning speed and the number of scans jointly affect the roughness of the processed surfaces and further the contact angle of static droplets. Due to the anisotropic wettability, the contact angle perpendicular to grooves is generally larger than that in the parallel direction. When the scanning speed is 540 mm/s and the number of scans is 75, the maximum contact angles in the perpendicular and parallel directions are 156.5°, 155.0°, respectively. One of the silicone rubber based superhydrophobic surfaces was then bent into convex shapes with various curvatures and a series of droplet impact experiments were performed on it. Compared to that on a flat superhydrophobic surface, the contact time of impacting droplets on the curved surface is reduced dramatically. It demonstrates that the flexible surfaces can also have improved repellency to dynamic droplets. This work provides an effective approach for repelling water through fabricating flexible superhydrophobic surfaces.

Large-area fabrication and applications of patterned surface with anisotropic superhydrophobicity

Recently, anisotropic superhydrophobic surfaces have aroused much attention due to their promising applications. However, large-area fabrication of low-cost superhydrophobic surfaces with obvious anisotropicity is still a huge challenge. In this work, a home-made melt hot-pressing method was proposed to facilely fabricate aligned micro-patterns on high-density polyethylene surface. Such surface displays anisotropic superhydrophobic characteristic with a static water contact angle of 152°and 145° respectively in parallel and perpendicular direction. Moreover, it has low surface adhesion and decent mechanical stability, showing promising applications for hydraulic triboelectric generator with self-cleaning ability, milk residue reduction and drag reduction. Considering the facile fabrication process and inexpensive thermoplastic polymer used, this study not only provides the possibility of large-area and low-cost preparation of orderly patterned surfaces with anisotropic superhydrophobicity, but also opens a new pathway toward wide application of anisotropic superhydrophobic surface.

Fabrication of Robust Superhydrophobic Surfaces with Dual-Curing Siloxane Resin and Controlled Dispersion of Nanoparticles

We developed a simple method for the fabrication of superhydrophobic surfaces on various substrates using spray coating. The fabrication method started with the blending of a modified hydrophobic siloxane binder, silica nanoparticles, and a volatile solvent by sonication. The mixture was spray-coated on various surfaces such as slide glass, paper, metal and fabric, forming a rough surface comprising silica particles dispersed in a hydrophobic binder. Surface hydrophobicity was affected by the surface energy of the binder and the degree of roughness. Therefore, we realized a superhydrophobic surface by controlling these two factors. The hydrophobicity of the siloxane binder was determined by the treatment of fluorine silane; the roughness was controlled by the amount of coated materials and sonication time. Thus, using the spray coating method, we obtained a superhydrophobic surface that was mechanically durable, thermally stable, and chemically resistant.

Fabrication and characterization of cauliflower-like silica nanoparticles with hierarchical structure through ion beam irradiation

The fabrication of superhydrophobic surfaces is an area of great interest to assorted engineering applications for instance as self-cleaning, anti-biofouling, anti-corrosion, anti-icing, and anti-sticking materials. A simple and inexpensive fabrication process is required to manufacture superhydrophobic surfaces industrially. In this work, we developed a facile process for the fabrication of superhydrophobic surfaces with the use of ion-beam irradiation with argon and oxygen gases. The process of ion beam irradiation was applied to understand the effects of irradiation on the surface morphology and substrate properties. After ion-beam irradiation, the surface morphology was altered to include microstructures with various types of surface roughness and forms. The as-prepared structured surfaces exhibited a high static contact angle (greater than 150°) and excellent superhydrophobicity owing to the synergistic effects of low-surface-energy materials. These results indicate that improving the surface hydrophobicity may solve selected problems associated with surfaces. • A facile process was developed to fabricate superhydrophobic surfaces. • Surface morphology obtained with ion beam irradiation with argon and oxygen gas. • Fine nanoscale roughness was applied to larger microscale roughness. • A technologically viable method to create superhydrophobic surfaces is presented.

Fabrication of self-cleaning superhydrophobic silicone rubber insulator through laser texturing

ABSTRACT Silicone insulators are gaining its importance in the transmission and distribution of the power system networks. This study proposes a simple and high throughput way of fabrication of superhydrophobic silicone surfaces. The Nd:YAG nanosecond pulse laser was used to engrave six different types of structures on silicone rubber. The water contact angle (CA) and contact angle hysteresis (CAH) were measured using drop shape analyser goniometer. The self-cleaning property of the structured silicone surfaces was tested. Among six types of patterns, the structures formed through 50% scanning overlapped possess high CA (159 ± 1°) with very low CAH (3°) which is desirable for any self-cleaning surface. However, a completely irradiated silicone surface gives the highest CA (163 ± 2°) with very high CAH (61.84°). The proposed work is a vital step towards making a superhydrophobic insulator surface without the use of any coating for high voltage power system applications.

Fabrication of superhydrophobic surfaces inspired by “stomata effect” of plant leaves via swelling-vesiculating-cracking method

Fabrication of superhydrophobic surfaces by simple techniques is of significant interest. Herein, inspired by the “stomata effect” of plant leaves, a superhydrophobic surface with bionic stomata randomly on polydimethylsiloxane (PDMS) is fabricated by a facile swelling-vesiculating-cracking method. Neither multistep modification of nanostructure nor introduction of low surface energy substance is carried out during the fabrication. The water contact angle (CA) of the bio-inspired superhydrophobic surfaces with stomata-like structures (BSSS) can reach 168.4 ± 1° with 8.9° sliding angle and less than 10° contact angle hysteresis (CAH). The structure and wettability of the BSSS are characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive spectrometry and X-ray photoelectron spectroscopy. The effects of swelling ratio, heat treatment temperature and surface morphology on the hydrophobicity of the BSSS are investigated systematically. Noticeably, the BSSS are provided with wonderful durability in organic solvents, ice water, and strong acid solution. Furthermore, a theoretical model for BSSS based on the Cassie-Baxter relation is established to elucidate the “stomata effect”. The model reveals that the water contact angle will reach 180° when the stomata-like structure is suitable. The fabrication of BSSS provides a potential strategy for the development of novel superhydrophobic materials.

Fabrication of superhydrophobic titanium surfaces with superior antibacterial properties using graphene oxide and silanized silica nanoparticles

In spite of the superior corrosion resistance, titanium is prone to biofouling, especially in marine environment. Here we report a new approach to create robust superhydrophobic (SHP) Ti surfaces with superior antibacterial property, using silane containing silica nanoparticles (Si np) functionalized Graphene oxide (GO). Anodized titanium was first electrophoretically coated with GO, which is then coated with Si np dispersed perfluorooctyltriethoxy silane. The atomic force microscopic (AFM) investigations revealed an enhanced rms roughness of ~200 nm for silane functionalized silica nanoparticles deposited over graphene oxide coated surface as compared to 60 nm for GO alone coated surface. Laser Raman Spectroscopy (LRS) and X-ray photoelectron spectroscopy (XPS) confirmed that the silanized silica nanoparticles are covalently bonded to the graphene oxide sheet. The micro-nano scale roughness due to the distribution of Si np over the wrinkled sheets of GO along with the low surface energy silane moieties provided a water contact angle (WCA) of 173° with zero tilting angle. The silane-graphene oxide coated samples showed 3–5 orders lesser gram-negative Pseudomonas sp. and gram-positive Bacillus sp. on bacterial adhesion as compared to control sample. In addition, hybrid superhydrophobic titanium exhibited excellent chemical stability and mechanical durability in marine environment.

Fabrication of superhydrophobic Eucalyptus wood surface with self-cleaning performance in air and oil environment and high durability

In this study, a simple and cost-effective method was developed to fabricate superhydrophobic coating on wood surface. The prepared superhydrophobic coating had a large water contact angle (159°), less water slide angle (6°), good durability, abrasion resistance property, excellent thermal stability, and good acid and alkali resistance property. Notably, the coatings had self-cleaning properties in air or oil environment. The superhydrophobic coating was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. We prepared the classical micro/nanostructured SiO2 on the wood surface on which the low surface free energy substance 1H,1H,2H,2H-perfluoroalkyltrichlorosilane (PFDS) was successfully modified. Furthermore, the treated wood had significantly better physical properties including water uptake and dimensional stability. The developed superhydrophobic coating is easy to fabricate and has great significance for the functional modification of wood.

Fabrication of robust superhydrophobic surfaces by one-step spray coating: Evaporation driven self-assembly of wax and nanoparticles into hierarchical structures

Mechanically durable superhydrophobic coatings have enormous application potential in almost all aspects of our daily lives. In this study, we present a practical strategy for one-step fabrication of robust superhydrophobic coatings based on evaporation driven self-assembly of hydrophobic nanoparticles and wax into hierarchical structures. Depending on the solvent and coating distance, spray-coating a dispersion composed of alkyl-silane functionalized nanoparticles and wax results in extremely water repellent surfaces with a water contact angle of 175° and a sliding angle of 3°. The formation of hierarchically structured surfaces upon evaporation of the solvent enables fabrication of fluorine-free, highly water repellent surfaces and provides high level of structural protection against mechanical abrasion. The coating retains its superhydrophobicity even after 1000 cycles of water spray impact, 45 min of water jet impact, and 180 cm of linear abrasion. The low-cost, scalable, one-step, and fluorine-free fabrication of superhydrophobic coatings that can be applied onto virtually any type of material surface with a satisfactory mechanical robustness based on eco-friendly and industrially available materials presents promising avenues for practical applications.

Advances in the Fabrication of Superhydrophobic Polymeric Surfaces by Polymer Molding Processes

Superhydrophobic materials are found in a suite of scientific and industrial applications, and given their broad potential use, there is great interest in facilitating their mass production. Although numerous methods have been used to produce superhydrophobic materials, only a few are capable of fabricating superhydrophobic surfaces and materials at an industrial scale. Techniques such as injection molding, compression molding, hot embossing, and polymer casting play an important role in the mass production of superhydrophobic polymer surfaces. This technical literature review summarizes recent advances in the polymer molding processes used to fabricate superhydrophobic materials. Here, we review replication methods and the materials that can be used by these approaches. We also evaluate the advantages and disadvantages of these methods and discuss the challenges of molding and demolding single-level structures (e.g., microstructures and nanostructures) and multilevel structures (e.g., micro-nanostructures, micro-microstructures, and micromicro-nanostructures), with a focus on superhydrophobic surfaces. We evaluate the relationship between structure geometry and the wettability of a surface, highlighting the effect of structure type and size in achieving the desired wettability. We then offer perspectives, discuss current limitations, and suggest required studies. This review aims to assist researchers in understanding the fundamentals related to the fabrication of patterned surfaces via polymer molding processes and offer avenues for the successful creation of superhydrophobic polymeric surfaces.

Superhydrophobic Surface Fabrication for Strengthened Selective Water Shut-off Technology

A two-step solution immersion method was used to successfully fabricate a superhydrophobic film on the surface of the core, which can effectively separate oil and water. The optimal reagent concent...

Fabrication of superhydrophobic surfaces based on fluorosilane and TiO2/SiO2 nanocomposites

ABSTRACT In this work, we reported a facile method to fabricate highly stable superhydrophobic coatings via blending two kinds of nanoparticles and crosslinked fluorosilanes. Simultaneous use of nano-TiO2 and hydrophobic nano-SiO2 cannot only synergistically construct multi-scale roughness structures on the superhydrophobic surfaces, but also greatly improve the hydrophobic stability of the superhydrophobic coatings. It was found that the water contact angle and contact angle hysteresis of the as-prepared coatings were, respectively, 166.6° and 3.4°. Owing to the excellent properties of crosslinked fluorosilanes, the composite coatings also exhibited good thermal stability, chemical stability and self-cleaning property. Owing to its flexibility and simplicity, the method is a facile and inexpensive way to achieve the lotus effect and exhibits high values in practical application.

A novel fabrication of superhydrophobic surfaces on aluminium substrate by picosecond pulsed laser

Superhydrophobic surfaces have emerged because of their unique properties like corrosion resistance, self-cleaning, anti-icing and being anti-bacterial. A simplistic and highly effective ultra-fast laser technology was used to fabricate superhydrophobic surface on aluminum substrate. Compared to other laser systems, picosecond laser systems have smaller thermal affected area on the aluminum substrate. They also offer high efficiency, not as much of waste materials and cover enormous areas for mass production. Tilted groove patterns of various angles with respect to horizontal were textured on the substrate by using picosecond laser pulses. The laser parameters, such as hatching distance (HD) and scanning speed (SS), can be varied by keeping the laser power as constant for the various tilted angle of the groove pattern. The textured surfaces were initially super hydrophilic when kept in polyethylene zip lock cover and which also exhibits super hydrophobicity of maximum 155.5° when observed after 15 days. The morphology of surface was characterized by scanning electron microscope, EDX and X-ray diffraction.

Fabrication of polymer-based water-repellent surfaces of complex shapes by physical transfer of nanostructures

This work reports large-area fabrication of polymer [polydimethylsiloxane (PDMS), polycaprolactone (PCL) and polytetrafluoroethylene (PTFE)]-based superhydrophobic surfaces decorated with Cu(OH)2 nanowires. The process flow involves fabrication of nanostructured copper hydroxide surface (Cu(OH)2_NSS) by etching and coating the Cu(OH)2_NSS with a hydrophobic silane layer. This is followed by transferring the nanowires on to the polymer surface. The fabricated surfaces [which are Cu(OH)2 nanowires on PDMS: PDMS_Cu(OH)2, Cu(OH)2 nanowires on PCL: PCL_Cu(OH)2 and Cu(OH)2 nanowires on PTFE: PTFE_Cu(OH)2] exhibited dual scale roughness imparting very good water repelling behavior with a static contact angle greater than 150° and contact angle hysteresis of less than 10°. In addition to water repelling behavior, the fabricated surfaces exhibited bloodphobic behavior making them suitable for specific healthcare applications. Using the same technique, fabrication of superhydrophobic surface with complex 3D shape was also demonstrated. The same methodology was further adopted to fabricate a large-area (22 cm × 22 cm) superhydrophobic surface by replacing silane with stearic acid, which is a non-fluorinated surface modifying agent. This helped in reducing the cost and time of fabrication which is important when it comes to large-scale manufacturing.