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1 – 10 of 155Pingping Hou, HongYan Huang, Yong Wang, Jun Zhang and Dewen Sun
The purpose of this study is to prepare a robust superhydrophobic coating on concrete substrate with remarkable chemical and mechanical durability through “all-covalent” strategy.
Abstract
Purpose
The purpose of this study is to prepare a robust superhydrophobic coating on concrete substrate with remarkable chemical and mechanical durability through “all-covalent” strategy.
Design/methodology/approach
Amino-modified silica nano/micro-particles were prepared through two synthetic steps. “All-covalent” strategy was introduced to prepare a robust superhydrophobic coating on concrete surface via a “all-in-one” dispersion and a simple spraying method. The successful construction of the products was confirmed by Fourier transform infrared spectroscopy, water contact angles (WCA), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The concrete protective properties were verified by solution immersion test, pull-off test and rapid chloride migration coefficient test. The mechanical durability was tested by falling sand impact.
Findings
Hierarchical structures combined with the low-surface-energy segments lead to typically superhydrophobic coating with a WCA of 156° and a sliding angle of 1.3°. The superhydrophobic coating prepared through “all-covalent” strategy not only improves chemical and mechanical durability but also achieves higher corrosion and wear resistance than the comparison sample prepared by physically blending strategy. More importantly, the robust superhydrophobic coating showed excellent adhesion and protective performance of concrete engineerings.
Practical implications
This new “all-covalent” superhydrophobic coating could be applied as a concrete protective layer with properties of self-cleaning, anti-graffiti, etc.
Originality/value
Introduction of both silica nanoparticles and silica microparticles to prepare a robust superhydrophobic coating on concrete surface through “all-covalent” strategy has not been systematically studied previously.
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Dexin Chen, Hongyuan He, Zhixin Kang and Wei Li
This study aims to review the current one-step electrodeposition of superhydrophobic coatings on metal surfaces.
Abstract
Purpose
This study aims to review the current one-step electrodeposition of superhydrophobic coatings on metal surfaces.
Design/methodology/approach
One-step electrodeposition is a versatile and simple technology to prepare superhydrophobic coatings on metal surfaces.
Findings
Preparing superhydrophobic coatings by one-step electrodeposition is an efficient method to protect metal surfaces.
Originality/value
Even though there are several technologies, one-step electrodeposition still plays a significant role in producing superhydrophobic coatings.
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Pingping Hou, Zhaohui Zhan, Shuai Qi, Yingjie Ma, Bo Li, Dewen Sun and Qianping Ran
The purpose of this study is to prepare a chemically stable superhydrophobic coating with remarkable mechanical properties and concrete protective properties.
Abstract
Purpose
The purpose of this study is to prepare a chemically stable superhydrophobic coating with remarkable mechanical properties and concrete protective properties.
Design/methodology/approach
One synthetic step was adopted to prepare superhydrophobic coating. The process and product were analyzed and confirmed by fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), water contact angle (WCA), transmission electron microscopy (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The mechanical properties were confirmed by tensile test. The concrete protective properties were confirmed by solution immersion test and rapid chloride migration coefficient test.
Findings
MSiO2 nanoparticles (NPs) were chosen to enhance the hydrophobicity of fluorosilicone coatings. With a 4:1 mass ratio of fluorosilicone resin and MSiO2 NPs, the coatings show superhydrophobicity with a WCA of 156° and a SA of 3.1°. In addition, the tensile mechanical property was improved, and the chloride ion diffusion coefficient was decreased significantly after the addition of MSiO2 NPs.
Practical implications
This new fluorosilicone coating hybrid by MSiO2 NPs could be applied as a concrete protective layer with properties of self-cleaning, antifouling, etc.
Originality/value
Introduction of MSiO2 NPs hybrid to prepare fluorosilicone coating with superhydrophobicity on concrete surface has not been systematically studied previously.
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A. Syafiq, A.K. Pandey, Vengadaesvaran Balakrishnan and Nasrudin Abd Rahim
The paper aims to investigate the effect of Degussa P-25 Titanium Dioxide (TiO2) nanoparticles on hydrophobicity and self-cleaning ability as a single organic coating on glass…
Abstract
Purpose
The paper aims to investigate the effect of Degussa P-25 Titanium Dioxide (TiO2) nanoparticles on hydrophobicity and self-cleaning ability as a single organic coating on glass substrate.
Design/methodology/approach
Two methods have been used to enhance the hydrophobicity on glass substrates, namely, surface modification by using low surface energy isooctyltrimethoxysilane (ITMS) solution and construction of rough surface morphology using Degussa P-25 TiO2 nanoparticles with simple bottom-up approach. The prepared sol was applied onto glass substrate using dip-coating technique and stoved in the vacuum furnace 350°C.
Findings
The ITMS coating with nano TiO2 pigment has modified the glass substrate surface by achieving the water contact angle as high as 169° ± 2° and low sliding angle of 0° with simple and low-cost operation. The solid and air phase interface has created excellent anti-dirt and self-cleaning properties against dilute ketchup solution, mud and silicon powder.
Research limitations/implications
Findings will be useful in the development of self-cleaning and anti-dirt coating for photovoltaic panels.
Practical implications
Sol method provides the suitable medium for the combination of organic–inorganic network to achieve high superhydrophobicity and optimum self-cleaning ability.
Originality/value
Application of blended organic–inorganic sol as self-cleaning and anti-dirt coating film.
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A. Gayathri, P. Varalakshmi and M. G. Sethuraman
This study aims to develop multifunctional, namely, superhydrophobic, flame-retardant and antibacterial, coatings over cotton fabric, using casein as green-based flame-retardant…
Abstract
Purpose
This study aims to develop multifunctional, namely, superhydrophobic, flame-retardant and antibacterial, coatings over cotton fabric, using casein as green-based flame-retardant and silver nanoparticles as antibacterial agent by solution immersion method.
Design/methodology/approach
The cotton fabric is first coated with casein to make it flame-retardant. AgNPs synthesized using Cinnamomum zeylanicum bark extract is coated over the casein layer. Finally, stearic acid is used to coat the cotton to make it superhydrophobic. X-ray diffraction, transmission electron microscopy analysis and ultraviolet-visible spectroscopy are used to investigate the produced AgNPs. The as-prepared multifunctional cotton is characterized by scanning electron microscopy, energy dispersive X-ray analysis and attenuated total reflection-infrared studies. Flame test, limiting oxygen index test and thermogravimetric analyzer studies have also been performed to study the flame-retardant ability and thermal stability of treated fabric, respectively. The antibacterial effect of the coatings is evaluated by disc-diffusion technique. Water contact angle is determined to confirm the superhydrophobic nature of cotton fabric.
Findings
The outcomes of this study showed that the prepared multifunctional cotton fabric had maximum contact angle of greater than 150° with good flame retardancy, high thermal stability, greater washing durability and high antibacterial activity against the growth of Pseudomonas aeruginosa and Acinetobacter indicus. Additionally, the as-prepared superhydrophobic cotton showed an excellent oil–water separation efficiency.
Research limitations/implications
The trilayered multifunctional cotton fabric has limiting washing durability up to 20 washing cycles. Treated functional fabric can be used as an antibacterial, therapeutic, water repellent and experimental protective clothing for medical, health care, home curtains and industrial and laboratory purposes.
Originality/value
The study brings out the robustness of this method in the development of multifunctional cotton fabrics.
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A. Syafiq, A.K. Pandey, Vengadaesvaran Balakrishnan, Syed Shahabuddin and Nasrudin Abd Rahim
This paper aims to investigate the thermal stability and hydrophobicity of difference alkyl chain of silanes with silicon (Si) micro- and nanoparticles.
Abstract
Purpose
This paper aims to investigate the thermal stability and hydrophobicity of difference alkyl chain of silanes with silicon (Si) micro- and nanoparticles.
Design/methodology/approach
Sol-gel methods have been used to design superhydrophobic glass substrates through surface modification by using low-surface-energy Isooctyl trimethoxysilane (ITMS) and Ethyl trimethoxysilane (ETMS) solution. Hierarchical double-rough scale solid surface was built by Si micro- and nanoparticles to enhance the surface roughness. The prepared sol was applied onto glass substrate using dip-coating method and was dried at control temperature of 400°C inside the tube furnace.
Findings
The glass substrate achieved the water contact angle as high as 154 ± 2° and 150.4 ± 2° for Si/ITMS and Si/ETMS films, respectively. The Si/ITMS and Si/ETMS also were equipped with low sliding angle as low as 3° and 5°, respectively. The Si micro- and nanoparticles in the coating system have created nanopillars between them, which will suspend the water droplets. Both superhydrophobic coatings have showed good stability against high temperature up to 200°C as there are no changes in WCA shown by both coatings. Si/ITMS film sustains its superhydrophobicity after impacting with further temperature up to 400°C and turns hydrophobic state at 450°C.
Research limitations/implications
Findings will be useful to develop superhydrophobic coatings with high thermal stability.
Practical implications
Sol method provides a suitable medium for the combination of organic-inorganic network to achieve high hydrophobicity with optimum surface roughness.
Originality/value
Application of different alkyl chain groups of silane resin blending with micro- and nanoparticles of Si pigments develops superhydrophobic coatings with high thermal stability.
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Siamak Nazemi, Ramin Khajavi, Hamidreza Rabie Far, Mohammad Esmail Yazdanshenas and Manouchehr Raad
During 2008 Olympics, Michael Phelps had a record-breaking performance. One contributing factor to his success was the full-body swimsuit he was wearing. Cases like these were the…
Abstract
Purpose
During 2008 Olympics, Michael Phelps had a record-breaking performance. One contributing factor to his success was the full-body swimsuit he was wearing. Cases like these were the reason for the initiation of study and research for improvement in the new generation of sport gears. The purpose of this paper is to show that drag force plays a significant role in swimmers’ speed through the water; thus, using swimsuit with minimized drag force becomes imperative for Olympians like Michael Phelps.
Design/methodology/approach
This paper shows a comparative evaluation of hydrodynamics of three PET fabrics with different finishings that have hydrophobic behavior over a range of Reynolds number 1.0218×103 and 1.365×103 in the air medium at 20°C ambient temperature, and Reynolds number ranging from 15.68856×103 to 20.958×103 in the water medium at 20°C ambient temperature under stable stretch conditions.
Findings
The results show that hydrophobic finishing reduces the drag force by 1.5 percent at the angles of attack of 0 and 90 degrees.
Originality/value
If all the factors are considered to be stable for the swimmer, the drag force reduces by 1.5 percent, thereby increasing the speed of swimmer by 1.22 percent, which means that the record of the swimmer improves by 0.819 seconds.
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Hongxia Wang, Hua Zhou, Haitao Niu, Chen Huang, Amir Abbas, Jian Fang and Tong Lin
In this study, superhydrophobic fabric is prepared with a wet-chemical coating technique that uses a coating solution synthesized by the co-hydrolysis and co-condensation of…
Abstract
In this study, superhydrophobic fabric is prepared with a wet-chemical coating technique that uses a coating solution synthesized by the co-hydrolysis and co-condensation of tetraethyl orthosilicate and fluoroalkyl silane (tridecafluorooctyl triethoxysilane) under an alkaline condition. The treated fabric shows stable superhydrophobicity with a water contact angle as high as 171°, and a sliding angle as low as 2°. The coated fabric has higher repellency to saline water, and its repellency increases with increases in the salt content in the solution. The contact angle is reduced with increases in liquid temperature. When the water temperature is 90°C, the contact angle on the superhydrophobic fabric is 153°. The superhydrophobic treatment slightly reduces the air permeability, but increases the water vapor permeability of the fabric. The treatment considerably increases the liquid breakthrough pressure, but has little effect on fabric pore size and thermal conductivity. The air gap membrane distillation process is used to evaluate the desalination performance of the superhydrophobic fabric. When the feed and the condenser are kept at 90°C and 20°C, respectively, the membrane distillation (MD) system with the superhydrophobic fabric yields a permeate flux of water up to 13.8 kg m-2 hour-1, which is slightly higher than that with the use of polymer and inorganic MD membranes reported. Superhydrophobic fabrics may thus be considered as effective MD membranes for water desalination applications.
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Zhengwei Song, Shengjian Zhang, Lifeng Ding, Xuejing Wu and Ning Long
The purpose of this paper was prepared a Ni-based superhydrophobic coating on the surface of copper to enhence its corrosion resistance. The superhydrophobic coating (SHPC) has…
Abstract
Purpose
The purpose of this paper was prepared a Ni-based superhydrophobic coating on the surface of copper to enhence its corrosion resistance. The superhydrophobic coating (SHPC) has proven to be an effective surface treatment in corrosion protection. In this paper, a Ni-based SHPC was prepared on the surface of copper (Cu) to enhance its corrosion resistance.
Design/methodology/approach
The coating was prepared through a two-step electrodeposition process. The first step involves the formation of a micro-nano structure Ni layer formed by an electrodeposition process. Subsequently, the polysiloxane layer was deposited on the Ni surface to create an SHPC. The morphology, composition, structure, wettability and corrosion resistance of the coating were characterized and discussed.
Findings
The results show that the water contact angle of the as-prepared coating reaches 155.5°±1.0°. The corrosion current density (icorr = 3.90 × 10−9 A·cm−2) decreased by three orders of magnitude compared to the substrate, whereas |Z|f = 0.01 Hz (2.40 × 106 Ω·cm2) increased by three orders of magnitude. It indicated that the prepared coating has excellent superhydrophobicity and high corrosion resistance, which can provide better protection for the substrate.
Originality/value
The prepared coating provides long-lasting protection for Cu and other metals and offers valuable data for developing SHPCs.
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Zhengwei Song, Zhi-Hui Xie, Lifeng Ding and Shengjian Zhang
This paper aims to comprehensively review the preparation methods of superhydrophobic surfaces (SHPS) for corrosion protection of Mg alloy in recent years.
Abstract
Purpose
This paper aims to comprehensively review the preparation methods of superhydrophobic surfaces (SHPS) for corrosion protection of Mg alloy in recent years.
Design/methodology/approach
The preparation methods, wettability and corrosion resistance of SHPS on Mg alloy in the past three years are systematically described in this paper.
Findings
Two types of SHPS, including single-layer and multilayer coatings for corrosion protection of Mg alloy are summarized. Preparing multilayered coatings with multifunction is the current trend in developing SHPS on Mg alloy.
Originality/value
This paper reviewed the preparation methods and corrosion resistance of SHPS on Mg alloys. It provides a valuable reference for researchers to develop highly durable SHPS with excellent corrosion resistance for Mg alloys.
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