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Study On Superhydrophobic Surface Of Green Magnetic Sheet From Durian Shell

Study On Superhydrophobic Surface Of Green Magnetic Sheet From Durian Shell

The study will focus on fabricating of superhydrophobic surface in green magnetic sheet from durian shell. Durian shell will be used as the main raw material to make green magnetic sheet by using lumen loading technique after the soda pulping process. Soda pulping is used in making the paper pulp and ensuring the separation between cellulose and lignin. The green magnetic sheet then is produced through lumen loading whereby the magnetic particles are inserted into the lumen of cellulose fibers. After the magnetic sheet paper formed, three superhydrophobic techniques will be applied in order to screen the best potential method that suite the durian shell. The techniques are dip coating using stearic acid, blending polymer via disintegration technique, and drop coating using modified silica particles and polystyrene (PS) emulsion.
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Stable superhydrophobic surface of hierarchical carbon nanotubes on Si micropillar arrays

Stable superhydrophobic surface of hierarchical carbon nanotubes on Si micropillar arrays

Generally, pristine carbon nanotubes (CNTs) are hydrophobic materials, which have also been used to construct a superhydrophobic surface [15,16]. By mak- ing micropatterns, the hydrophobicity of a CNT surface is further enhanced. The CA between water and CNT pattern is usually larger than 150°, but the SA is also large (usually larger than 30°) [17,18]. However, the superhydrophobic CNT forest might also absorb water, resulting in collapsing into cellular foams when water evaporates from interstices of nanotubes [19]. After wet- ting, the CNT forest might lose its superhydrophobic properties. It needs to construct a stable and durable superhydrophobic surface even wetted by vapor or tiny water droplets. Here, we fabricate the superhydrophobic hierarchical architecture of CNTs on Si micropillar array (CNTs/Si-μp) with large CA and ultralow SA. The CNTs/ Si-μp show a durable superhydrophobic surface even after wetting using tiny water droplets.
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Fabrication of Superhydrophobic Surface of ZnO Thin Films by Using Oleic Acid

Fabrication of Superhydrophobic Surface of ZnO Thin Films by Using Oleic Acid

Abstract: Zinc oxide (ZnO) nanostructures were successfully prepared by a simple, highly efficient, and low-cost using the hydrothermal method. A superhydrophobic surface with a static water contact angle (CA) >150° has been synthesized by modifying ZnO nanostructures with 100°C at 1 h stable oleic acid (OA) as coupling agents, in order to modify their surface properties and make them more hydrophobic. Surface modification of ZnO nanostructures has been performed, and the effect of the modification on the structure and morphological properties were investigated. The resulting nanostructures were characterized by XRD, FESEM, UV-VIS spectroscopy. XRD pattern revealed that ZnO nanostructures prepared by hydrothermal method (crystallite size ~30 nm) have hexagonal wurtzite structure with a good crystalline quality. FESEM images of ZnO nanostructures prepared by hydrothermal showed hexagonal nanorods assembled in flower-like shape, there was much change in the surface morphology of modified samples after surface modification such as (nanorods, nanoflowers, and nanotube). Results show the water CA of ZnO superhydrophobic surfaces increased steadily from 147±2° to 154±2° when the OA weight percentage increased from 2mg to 10mg. The optical measurements for ZnO nanostructures showed that all samples the absorption band in the ultraviolet region. The band gap of pure ZnO nanostructures 3.5 eV and after modification ZnO surface 3.6 eV. All samples of ZnO were maintained at room temperature for 1 hour to 5 months to test the stability of the surface. The water CAs were measured for each condition, and very little change was observed in the CAs. In addition, the ZnO surface remained superhydrophobic without any contamination observed after water was sprayed on it.
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Anti-corrosion Properties of a Bioinspired superhydrophobic surface on Stainless Steel

Anti-corrosion Properties of a Bioinspired superhydrophobic surface on Stainless Steel

Compared with other technologies, chemical etching can be considered because of its economic advantage. Therefore, this work demonstrates chemical etching method to fabricate superhydrophobic surface inspired by “lotus effect.” The functional superhydrophobic surface is fabricated on stainless steel via a two-step etching method; the first step involves the fabrication of micron pore structures, whereas the second step is patterning nano pits on these micro pore structures. The micro–nano structures are similar to the surface of lotus leaf, in which micropapillae were covered by branch-like nanostructures. The electrochemical corrosion characterization shows that the bioinspired superhydrophobic stainless steel surface possesses markedly higher polarization resistance (R p ) than
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A novel CVD Method for Rapid Fabrication of Superhydrophobic Surface on Aluminum Alloy Coated Nanostructured Cerium-Oxide and Its Corrosion Resistance

A novel CVD Method for Rapid Fabrication of Superhydrophobic Surface on Aluminum Alloy Coated Nanostructured Cerium-Oxide and Its Corrosion Resistance

Cerium-oxide film with a micro/nano-scale hierarchical structure was fabricated on aluminum surface by a hydrothermal process. The boiling water treatment is an facile and environmentally- friendly method to pretreat the aluminum substrate, and vital to fabricate the flower-like rough structure. Superhydrophobicity of cerium-oxide film could be easily gained by a novel CVD method. As the immersion time extended, the SA decreased and the corrosion potential considerably shifted to the positive direction, showing the enhancement of corrosion resistance. This change was related to the contact state, which transferred from Wenzel state to Cassie–Baxter state. At Cassie–Baxter state, a stable air layer formed on the superhydrophobic surface, which was vital to the superhydrophobic film’s anticorrosion property. FTIR results indicated that the CVD method was more efficient than liquid-phase method for superhydrophobic modification by PFOTES deposition. Furthermore, in combination with the results of LP, E oc -t and EIS, ASS can be concluded to have superior corrosion
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Facile synthesis of superhydrophobic surface of ZnO nanoflakes: chemical coating and UV induced wettability conversion

Facile synthesis of superhydrophobic surface of ZnO nanoflakes: chemical coating and UV induced wettability conversion

This work reports an oriented growth process of two-dimensional (2D) ZnO nanoflakes on aluminum substrate through a low temperature hydrothermal technique and proposes the preliminary growth mechanism. A bionic superhydrophobic surface with excellent corrosion protection over a wide pH range in both acidic and alkaline solutions was constructed by a chemical coating treatment with stearic acid (SA) molecules on ZnO nanoflakes. It is found that the superhydrophobic surface of ZnO nanoflake arrays shows a maximum water contact angle (CA) of 157° and a low sliding angle of 8°, and it can be reversibly switched to its initial superhydrophilic state under ultraviolet (UV) irradiation, which is due to the UV-induced decomposition of the coated SA molecules. This study is significant for simple and inexpensive building of large-scale 2D ZnO nanoflake arrays with special wettability which can extend the applications of ZnO films to many other important fields.
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Product and process fingerprint for nanosecond pulsed laser ablated superhydrophobic surface

Product and process fingerprint for nanosecond pulsed laser ablated superhydrophobic surface

114 115 2.1 Analysis of process fingerprint candidates: laser power, exposure time, laser pulse energy per unit area of specimen 116 Laser power P 117 118 119 120 121 122 123 124 In a na[r]

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Superhydrophobic Surface Based Silica Nanoparticle Modified With Diisocyanate and Short and Long Normal Chain Alcohols

Superhydrophobic Surface Based Silica Nanoparticle Modified With Diisocyanate and Short and Long Normal Chain Alcohols

In this study, we have developed the synthesis of SH nanoparticles, without using fluoride groups, which are resistant to acidic and basic condition and also the commercially available raw materials for extending formulation at industrial scale. To achieve this goal we modified hydroxile group on silica nanoparticle with toluene diisocyanate, then, we added alcohols of varying lengths. Hydroxyl group of alcohols react with another isocyanate groups on the silica surface and form a urethane bond (Scheme 1). A two-step synthesis method has been used to make this nanoparticle without the need of a catalyst. Synthesized SH nanoparticle with high contact angle, acid and base resistance,and affordability can be used in practical applications.
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Fabrication of Mechanically Stable Superhydrophobic Aluminium Surface with Excellent Self-Cleaning and Anti-Fogging Properties

Fabrication of Mechanically Stable Superhydrophobic Aluminium Surface with Excellent Self-Cleaning and Anti-Fogging Properties

The surface morphology analysis reveals the presence of rough microstructures on etched aluminium surface. A static contact angle of 170 ± 3.9° with 4 ± 0.5° sliding angle is obtained of aluminium surface after chemical modification by lauric acid. The coated sample remains floating on the water surface for several weeks, showing excellent water-repellent nature. Superhydrophobic surface bounces off the water jet of high speed stream and no change in superhydrophobicity is found, indicating excellent mechanical strength of coating. Coating withstands 100 cycles of adhesive tape peeling test and after that it loses superhydrophobicity and achieves sticky superhydrophobicity. Additionally, mechanical disturbances due to bending and repeated folding and de-folding have not much effect on the superhydrophobicity. Coating shows the excellent self-cleaning property. Almost no accumulation of moisture from air on the cooled superhydrophobic surface asserts the excellent anti-fogging property of coating. The aforesaid mechanical stable superhydrophobic aluminium surfaces have potential industrial applications.
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Energy Efficiency Optimization of Superhydrophobic Surfaces for Enhanced Condensation Heat Transfer

Energy Efficiency Optimization of Superhydrophobic Surfaces for Enhanced Condensation Heat Transfer

For the physical experiments, the superhydrophobic surface has been prepared on copper alloy UNS C17000 by covering the surface with a thin layer of a paraffin film and subsequently by a layer of hydrophobic fumed silica. The prepared specimen was then heated to 50ºC to create a bond between the silica and paraffin films. Any excess silica powder was cleaned from the surface by a pressurised air jet. Such a prepared surface is superhydrophobic with a measured static contact angle of θ s =157±2º

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Influence of Weather Conditions on the Surface Morphology and Wetting Behaviour of Superhydrophobic Quaking Aspen Leaves

Influence of Weather Conditions on the Surface Morphology and Wetting Behaviour of Superhydrophobic Quaking Aspen Leaves

The average contact and tilt angles for all quaking as- pen leaves analyzed throughout the summer of 2011 are plotted in Figure 7. This plot can be broken down into 3 distinct regions showing vastly different wetting proper- ties. Leaves obtained the first week after emergence showed only a weak hydrophobic surface property with an average contact angle slightly above 90˚ and a rela- tively large tilt angle of 26˚. Just eight days after the first sampling, significant changes in surface structure and wetting properties were observed. The surface structure of the second set of samples had substantially trans- formed (Figure 2) resulting in much higher contact an- gles (148˚) and much lower tilt angles (<5˚). Following this initial change, for most of the summer season until August 21, 2011, aspen leaf contact angles remained high (140˚ - 160˚) and tilt angles remained low (<5˚). During this time the contact and tilt angles fluctuated slightly but for the most part remained close to the super- hydrophobic range (CA > 150˚ and TA < 5˚). Similar fluctuations in the contact angles throughout the growing season as observed here in region 2 were previously re- ported for ginkgo (Ginkgo biloba), oak (Quercus robur) and beech (Fagus sylvatica) leaves [18]. These fluctua- tions could be due to small surface structure differences on the different leaf samples. Another reason could be that leaves collected at different times throughout the year are at different stages in the wax crystal erosion/re- generation cycles. However, after August 21, 2011 the non-wetting property of the quaking aspen leaves was permanently lost resulting in low contact and high tilt angles. Again, it is important to note that leaves har- vested from the same tree in previous years (2007-2010) did not show a reduced non-wetting property at the end of past growth seasons [8]. Moreover, leaves from pre- vious years still exhibited extreme non-wetting properties and associated superhydrophobic surface structures after
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Facile Fabrication of Breathable and Superhydrophobic Fabric based on Silica Nanoparticles and Amino Modified Polydimethylsiloxane

Facile Fabrication of Breathable and Superhydrophobic Fabric based on Silica Nanoparticles and Amino Modified Polydimethylsiloxane

One of the widely studied strategies for fabrication of superhydrophobic textiles is based on increasing the surface roughness by coating of the surface with inorganic nanoparticles through the sol-gel process and subsequently lowering the surface energy by attachment of a hydrophobic compound on its surface. Also, using a sol, modified with an appropriate hydrophobic compound, may lead to a superhydrophobic surface coating by a one step process [6]. Hoefnagels et al. [7] turned the hydrophilic cotton to superhydrophobic by a two-step process including the sol-gel based in-situ growing of silica micro-particles on cotton fibers followed by a hydrophobization step using polydimethylsiloxane (PDMS). Xu et al. [8] examined the coating of cotton surface with SiO 2 nanoparticles or ZnO nanorods for creation of nano-roughness and modification of the
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Design and Development of Superhydrophobic Textile Surfaces

Design and Development of Superhydrophobic Textile Surfaces

A superhydrophobic surface is obtained by two criteria: a low surface energy and an appropriate surface roughness which results in water detaching from the surface at a low roll-off angle. In order to make nylon 6,6 superhydrophobic, a low surface tension material, 1H, 1H-perfluorooctylamine or octadecylamine was grafted onto nylon 6,6 woven fabric consisting of multifilament yarns. We modeled the multifilament, plain woven fabric as consisting of monofilaments whose water contact angle was equal to the apparent water contact angle of the multifilament yarn. We approximated the fabric as parallel cylinders with radii equal to that of the multifilament yarns. From the water contact angles measured on flat, modified nylon films, we predicted the apparent contact angle of the woven fabrics. Good agreement between the predicted values and the observed contact angles was obtained. Apparent water contact angles of the multifilament woven fabric as high as 168° were obtained. A flattened fabric was also modeled and the predicted and measured values for this fabric also were in good agreement. It is important to note that the form of the Cassie-Baxter equation in common use today is generally invalid, and the original Cassie- Baxter equation or the reformulated Cassie-Baxter equation by Marmur have to be used when the top of a rough surface is not completely flat.
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Simple Fabrication of Superhydrophobic Nickel Surface on Steel Substrate via Electrodeposition

Simple Fabrication of Superhydrophobic Nickel Surface on Steel Substrate via Electrodeposition

with stearic acid, the rough surface was modified from superhydrophilic to superhydrophobic. When electrodeposition current density was 60 A/dm 2 , the as-prepared nickel surface showed excellent superhydrophobicity with a contact angle of 154.4° and a sliding angle of about 2.0°, and possessed micro-nano rough structures. Besides, the superhydrophobic nickel surface also had a good anti- corrosion performance. It is believed that the presented approach should have a prosperous future in industrial applications for the superhydrophobic surface fabrication on steel substrates.
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An Experimental Study of Drag Reduction in a Pipe with Superhydrophobic Coating at Moderate Reynolds Numbers

An Experimental Study of Drag Reduction in a Pipe with Superhydrophobic Coating at Moderate Reynolds Numbers

The second way to form a superhydrophobic surface is to modify the surface, for example, with coating. In most early studies, polymer coatings were employed for drag reduction. Jones and Thurston [9] applied non-newtonian soluble polymer coating on surfaces of underwater vehicles. The frictional resistance was reduced 30 percent in freshwater and 27 percent in seawater. McCormick et al. [10] employed high molecular weight, water-soluble copolymers and conducted a series of drag reduction tests. Their results showed that the effectiveness of drag reduction was dependent on polymer structures and polymer-solvent interactions. In addition, Watanabe et al. [11, 12] carried out experiments on highly water-repellant walls formed by the coating of a fluorine- alkane-modified acrylic resin with added hydrophobic silica. The coating resulted in a hydrophobic surface crisscrossed by microcracks of 10-20 P m in width. Pressure drop and velocity profile measurements demonstrated drag reduction up to 18% and slip lengths up to 450 P m for flows at Reynolds numbers between 500 and 10,000.
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Wettability Switching Techniques on Superhydrophobic Surfaces

Wettability Switching Techniques on Superhydrophobic Surfaces

Among all the superhydrophobic surfaces displaying high roughness combined with low surface energy coating, trapping of air between the substrate and the liquid droplets is necessary to obtain a rolling ball effect (i.e. a quasi null hysteresis). Associated to an effective way to switch the wettability properties of the surface, control of droplet displacement on superhydrophobic surface seems to be possible. Unfortunately, only few techniques based on optical, electrical, mechanical or magnetic phenomenon, lead to a reversible modification of surface wettability. Among these techniques, electrowetting on classical surfaces (i.e. hydrophobic) seems to be the more mature technology. This is particularly emphasized by recent results on EWOD droplet liquid pixel and by the very last improvement concerning optical lenses integrated inside commercialized cellular phones (varioptic.com). Combin- ing the amazing properties of superhydrophobic surfaces with reliable EWOD devices will open new opportunities for designing systems with potential applications based on specific properties of theses surfaces, in particular in the field of lab-on-chip (preparation of highly functional microfluidic devices), optical devices and controlled self cleaning surfaces. Concerning lab-on-chip devices, the most important effect expected, due to the quasi null hysteresis of these surfaces, is the liquid manipulation at very low tension voltage.
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Superhydrophobic and Superoleophobic Nonwoven Fabrics.

Superhydrophobic and Superoleophobic Nonwoven Fabrics.

Superhydrophobicity has attracted considerable attention over the past two decades in industry and academia. Superhydrophobic surfaces are those that exhibit apparent contact angles of 150° and greater with water (Barthlott and Neinhus, 1997; Wu X and Shi G, 2006; Michielsen and Lee, 2007). These surfaces are particularly useful in those fields where water-repellent and self-cleaning properties are essential (Zhang et al, 2008; Li et al 2009; Bhushan et al, 2009). Many strategies have been adopted to create a superhydrophobic surface (Sun et al, 2005; Callies and Quere, 2005). Most of these surfaces have been inspired by natural objects such as lotus leaf, lady‟s mantle leaf, and desert beetle‟s back. Also, duck‟s feather, water strider‟s legs or gecko‟s feet (Barthlott and Neinhus, 1997; Gao and Jiang 2004; Parker and Lawrence, 2001; Liu et al, 2008; Autumn et al, 2000; Genzer and Efimenko, 2006). The two key elements that determine superhydrophobicity are surface energy and surface roughness (Lee and Michielsen, 2007). Mainly two techniques evolved for designing a superhydrophobic surface, 1) Roughening of a surface followed by hydrophobization, and 2) transforming low-surface-energy materials into rough surfaces (Xue et al, 2010). Different approaches have been attempted to realize the techniques such as sol-gel processing, wax solidification, lithography, vapour deposition, template reproduction, polymer reconformation, plasma, electrospinning, electrochemical methods, hydrothermal synthesis, layer-by-layer deposition and one-pot reactions (Zhang et al, 2008).
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Backscattering particle immunoassays in wire-guide droplet manipulations

Backscattering particle immunoassays in wire-guide droplet manipulations

positioning stage was moved to the right so that the target droplet moved to the right with the superhydrophobic surface, while the particle droplet was fixed with a metal wire. Once the two droplets were merged, the positioning stage was moved downward to remove the metal wire. The merged droplet was then moved to the right so that it was positioned underneath the backscattering probe. The backscattering probe with optical fibers was purchased from Ocean Optics (Dunedin, FL, USA); it consists of a core-shell bundle of optical fibers and is shown on the right in Figure 8. A single fiber at the core delivers 375-nm light from a light emitting diode (LED; LS-450 from Ocean Optics) and six fibers at the shell side collect 180° backscattered light and transfer the signal to a USB4000 miniature spectrometer (from Ocean Optics). The posi- tioning stages were moved along the X-, Y- and Z-direc- tions to collect the maximum light intensity. SpectraSuite software (from Ocean Optics) was used to collect light Snapshots from rapid mixing of a merged droplet
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Synthesis and Characterization of Superhydrophobic Coatings

Synthesis and Characterization of Superhydrophobic Coatings

Superhydrophobic coatings have drawn much attention in recent years because of their unique potential industrial applications. The prepared coating is cheap and versatile and can be applied on various substrates including glass, paper, acrylic, transparency and wood. Furthermore, the SHCs exhibit good long-term stability, water-durability and UV-durability, adapting to out-door environment. Above all, the coatings are environmental, low cost and can be quickly coated on various large-scale substrates, which will widen their practical applications. Two distinct theoretical models have been used to guide the generation of superhydrophobic surface by either roughening the surface or lowering the surface free energy, or both.The increasing interest in studying and manufacturing hydrophobic surface results from their possible practical applications. They find their primary use in corrosion, erosion or general degradation protection applications on metallic, polymer and inorganic oxide (stone, glass, ceramic, etc.) solid surfaces. In recent years, this field has evolved into a major industry trade which covers modern applications from anti-fogging as well as water and snow repellent surfaces for construction materials, glass, automotive and aerospace technology, all the way to reduce frictional drag on airplane wings and ship hulls.
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Recent Progress in Preparation of Superhydrophobic Surfaces: A Review

Recent Progress in Preparation of Superhydrophobic Surfaces: A Review

Biomimetic surfaces and materials received great atten- tion of scientists and engineers due to their unusual prop- erties. Biologically inspired design, adaptation, or deriva- tion from nature is referred to as “biomimetics” [1] Bio- logical tiny structures have been observed on many kinds of surfaces such as lotus leaves, rice leaves, butterfly wings, mosquito eyes, moth eyes, cicada wings, red rose petals, gecko feet, desert beetle, spider silks, and fish scales which exhibit excellent hydrophobicity and/or superhydropho- bicity [2-6]. Such natural structures offer new insights into the design of artificial superhydrophobic structures. A superhydrophobic surface is a surface on which a drop of water forms an almost perfect sphere and even a very slight tilting is sufficient to cause the water drop to roll off. In addition to high water contact angle and low slid- ing angle, the ability of a surface to bounce off water droplets constitutes the third property of a superhydro- phobic surface that is important for both biological and technical applications [7]. These surfaces are of special interest, because properties such as anti-sticking, anti-con- tamination, and self-cleaning are expected. These proper- ties are attractive for many industrial and biological ap- plications such as anti-biofouling paints for boats, antis-
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