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![The photos of some lotus leaves (a) and of a water droplet on a lotus leaf (b) and the SEM images of lotus leaves with different magnifications (c and d). The inset of (d) is a water contact angle on a lotus leaf, with a value of 161 ◦ ± 2 ◦ [5].](profile/Reza-Jafari-4/publication/257636131/figure/fig1/AS:297633596887044@1447972787798/The-photos-of-some-lotus-leaves-a-and-of-a-water-droplet-on-a-lotus-leaf-b-and-the.png)
The photos of some lotus leaves (a) and of a water droplet on a lotus leaf (b) and the SEM images of lotus leaves with different magnifications (c and d). The inset of (d) is a water contact angle on a lotus leaf, with a value of 161 ◦ ± 2 ◦ [5].
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Superhydrophobic surfaces, originally inspired by nature, have gained a lot of interest in the past few decades. Superhydrophobicity is a term attributed to the low adhesion of water droplets on a surface, leading to water contact angles higher than 150°. Due to their vast variety of possible applications, ranging from biotechnology and textile ind...
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... surfaces, originally inspired by nature, have gained a lot of interest in the past few decades. Superhydrophobicity is a term attributed to the low adhesion of water droplets on a surface, leading to water contact angles higher than 150 ◦ . Due to their vast variety of possible applications, ranging from biotechnology and textile industry to power network management and anti-fouling surfaces, many methods have been utilized to develop superhydrophobic surfaces. Among these methods, plasma technology has proved to be a very promising approach. Plasma technology takes advantage of highly reactive plasma species to modify the functionality of various substrates. It is one of the most common surface treatment technologies which is widely being used for surface activation, cleaning, adhesion improvement, anti-corrosion coatings and biomedical coatings. In this paper, recent advances in the applications of plasma technology in the development of superhydrophobic surfaces are discussed. At first, a brief introduction to the concept of superhydrophobicity and plasma is presented, then plasma-based techniques are divided into three main categories and studied as to their applications in development of superhydrophobic surfaces. Keywords: Plasma polymerization, etching, sputtering, superhydrophobic surfaces, thin films, nano-structured surfaces Wettability of a surface depends on its chemical composition and surface micro/nano roughness. These two parameters determine the extent of adhesive forces between a liquid droplet and the surface. Superhydrophobicity is where surface roughness meets low surface energy, so the adhesion force between water droplet and solid surface significantly decreases [1]. The concept of superhydrophobicity initially emerged from the investi- gation of natural surfaces with high contact angle and low contact angle hysteresis, notably the lotus leaf (Nelumbo) surface (Figure 1) [2, 3, 4]. Lotus is usually considered as a symbol of purity due to its self-cleaning effect [2, 6]. The superhydrophobic characteristics of the micro- nanostructured and wax-coated surface of the lotus leaf was first studied by Dettre and Johnson in 1963 [7]. Since then, several other examples of natural superhydrophobic surfaces have been ...
Citations
... It's crucial to recognize that enhancing surface roughness through plasma etching involves selective rather than uniform etching, as the latter can reduce surface roughness [53]. Consequently, plasma treatments can effect substantial modifications in the surface structure. ...
... The advantage of using atmospheric pressure plasma compared with other existing plasma technologies for producing superhydrophobic surfaces [31,32] is rest on irrelevant for expensive vacuum facilities or the use of chemical compounds that may be harmful to human health, making it an economical and environmentally friendly technology. In addition, the plasma method allows for extensive control of the synthesis parameters [33], thereby influencing the properties of the resulting material. The production of hydrophobic surfaces using atmospheric pressure plasma is a relevant and prospective area of research. ...
The paper was devoted to the results of the study of methods to obtain superhydrophobic film based on the plasma polymerisation of hexamethyldisiloxane (HMDSO) inside the plasma jet at atmospheric pressure. The 3D printing technology was intended for film deposition, which has the advantage of producing superhydrophobic surfaces over a wide range of scales. The effect of synthesis parameters on the hydrophobic properties of the film has been studied. The obtained superhydrophobic films demonstrated stability and resistance in chemical solutions, at high temperatures, under the influence of UV-irradiation and in various weather conditions. The results can be used in various fields, including automotive, construction, electronics, medicine and others, where surface protection against moisture, contamination and corrosion is required.
... Considerable research has been conducted to alter the surfaces of plasticized PVC medical devices to reduce or prevent the attachment of microorganisms and the formation of biofilms [6,7]. The two types of techniques that have been investigated include surface coating with ceragenin-type peptides and plasma treatment [8][9][10]. An additional approach that has been used is to develop antibacterial and antifungal ceragenins as non-peptides [11][12][13][14][15]. ...
An endotracheal tube (ETT) is a greatly appreciated medical device at the global level with widespread application in the treatment of respiratory diseases, such as bronchitis and asthma, and in general anesthesia, to provide narcotic gases. Since an important quantitative request for cuffed ETTs was recorded during the COVID-19 pandemic, concerns about infection have risen. The plasticized polyvinyl chloride (PVC) material used to manufacture ETTs favors the attachment of microorganisms from the human biological environment and the migration of plasticizer from the polymer that feeds the microorganisms and promotes the growth of biofilms. This leads to developing infections, which means additional suffering, discomfort for patients, and increased hospital costs. In this work, we propose to modify the surfaces of some samples taken from commercial ETTs in order to develop their hydrophobic character using surface fluorination by a plasma treatment in SF6 discharge and magnetron sputtering physical evaporation from the PTFE target. Samples with surfaces thus modified were subsequently tested using XPS, ATR-FTIR, CA, SEM + EDAX, profilometry, density, Shore A hardness, TGA-DSC, and biological antimicrobial and biocompatibility properties. The obtained results demonstrate a successful increase in the hydrophobic character of the plasticized PVC samples and biocompatibility properties.
... Every year the substantial increase in the number of research papers and patents on the use of plasma technology for producing a variety of new materials and functional coatings is indicating the myriad of opportunities created by plasma technology [14]. Plasma-based methods are highly prevalent in surface treatment technologies and find extensive application in areas such as cleaning, surface activation, enhancing adhesion, corrosion resistance, biomedical applications, and the development of self-cleaning coatings [14][15][16][17][18][19][20]. ...
... Every year the substantial increase in the number of research papers and patents on the use of plasma technology for producing a variety of new materials and functional coatings is indicating the myriad of opportunities created by plasma technology [14]. Plasma-based methods are highly prevalent in surface treatment technologies and find extensive application in areas such as cleaning, surface activation, enhancing adhesion, corrosion resistance, biomedical applications, and the development of self-cleaning coatings [14][15][16][17][18][19][20]. Variation of electron density with gas temperature for gas discharges of the typical atmospheric cold plasma. ...
The role of gaseous plasma has proven to be very beneficial in creating self-cleaning of various surfaces. Few references are there, in the published literature, on plasma enhanced hydrophilicity/hydrophobicity behavior of surfaces. A range of atmospheric pressure plasma spray systems are gaining popularity for creating self-cleaning surfaces, with some unique features, as also to fabricate new types of self-cleaning materials. In this chapter a brief introduction to essentials of plasma processing will be first presented, followed by examples of plasma assisted surface modification. This will include plasma cleaning, plasma etching, plasma polymerization/deposition, etc. Subsequently, various plasma assisted techniques to achieve a variety of self-cleaning surfaces will be highlighted. A unique combination of plasma-based approaches and sol–gel derived coating will also be discussed.
... The surface morphology was easily controlled by varying the growth time, as shown in Fig. 16(ad). Yang et al. developed superhydrophobic silica nanofibrous membranes with robust thermal stability and flexibility through the combination of in situ polymerization and the electrospinning process (Jafari et al., 2013). Initially, silica nanofibers (SNF) were formed through an electrospinning process with an applied voltage of 18 kV and a controllable feed rate of 1 mL/h. ...
... The poor thermal stability of the polymeric membrane has significantly limited its use in practical applications. To address this, Yang et al. fabricated thermally stable superhydrophobic membranes by using the electrospinning process (Jafari et al., 2013). The SiO 2 nanoparticles were modified by BaF-tfa molecules via in-situ polymerization to enhance the superhydrophobicity. ...
... The gas plasma is also a source of radiation that can break chemical bonds of the material [48]. The effect of the plasma discharge in the treated membrane relies on the type and conditions of the supplied gas, pressure, the power of the discharge, the duration of the treatment and the configuration of the chamber and electrodes [44,[49][50][51]. Thus, a chemical and/or physical modification can be induced on the membrane surface depending on the plasma conditions [47,49] since the ion bombardment and interaction with the different reactive species contained in the plasma can produce sputtering of the membrane material (etching), substitution reactions, atom abstraction, removal of volatile substances and/or scission of polymer chains [4,46,52,53]. ...
... This hydrophilic behaviour was mainly attributed to the generation of oxygen functional groups (hydroxyls, peroxides and carbonyls) [38]. After the preliminary experiments, and based on the literature [50], the power and time of the plasma treatment and the type of SiP were found to be the main factors to be optimised. The effects of these factors and their interactions can be observed in the Pareto diagram of the design shown in Figure 1. ...
... The reactions involved in the grafting process with TEOS are detailed elsewhere [64]. In contrast, the use of APTES can lead to the formation of siloxane chains with additional alkyl chains [39] that are naturally hydrophobic [40,50] and come from the aminopropyl group present in the APTES molecule. Moreover, the presence of an amine group can involve additional grafting reactions in the oxygen-rich active sites on the plasma-treated surfaces. ...
Superhydrophobic poly(vinylidene fluoride) (PVDF) membranes were obtained by a surface treatment consisting of oxygen plasma activation followed by functionalisation with a mixture of silica precursor (SiP) (tetraethyl-orthosilicate [TEOS] or 3-(triethoxysilyl)-propylamine [APTES]) and a fluoroalkylsilane (1H,1H,2H,2H-perfluorooctyltriethoxysilane), and were benchmarked with coated membranes without plasma activation. The modifications acted mainly on the surface, and the bulk properties remained stable. From a statistical design of experiments on surface hydrophobicity, the type of SiP was the most relevant factor, achieving the highest water contact angles (WCA) with the use of APTES, with a maximum WCA higher than 155° for membranes activated at a plasma power discharge of 15 W during 15 min, without membrane degradation. Morphological changes were observed on the membrane surfaces treated under these plasma conditions, showing a pillar-like structure with higher surface porosity. In long-term stability tests under moderate water flux conditions, the WCA of coated membranes which were not activated by oxygen plasma decreased to approximately 120° after the first 24 h (similar to the pristine membrane), whilst the WCA of plasma-treated membranes was maintained around 130° after 160 h. Thus, plasma pre-treatment led to membranes with a superhydrophobic performance and kept a higher hydrophobicity after long-term operations.
... Therefore, combined effect of all three decides whether a water drop on a solid substrate will behave as a water film or a spherical droplet. The smooth surfaces can give the CA up to 120 o , however, it can be enhanced by introducing the effect of roughness on the solid/liquid interface [8]. The effect of surface roughness on its wettability is studied in detail by two wellrenowned models Wenzel [9] and Cassie-Baxter model [10], as described below. ...
Corrosion, an undesirable phenomenon, negatively affects the desirable properties of materials and has become a serious problem in various industries. Prevention of corrosion is a great challenge but very important for economical and technological growth. In this regard, superhydrophobic surfaces (SHSs) have gained enormous research interest due to their broad industrial applications. However, more in-depth knowledge is required to explore SHSs for real practical applications. There is a need for introducing simple and cost-effective fabrication techniques and tailoring of surface properties such as roughness, and surface morphologies important for improving the durability robustness characteristics. The present review focuses on recent developments in the fabrication of SHSs with different approaches, its applications, challenges, and future perspectives, especially in the anti-corrosive application.
... Creating a superhydrophobic surface involves several approaches, such as chemical vapour deposition, wet chemical reactions, electrochemical deposition, the layer-by-layer method, self-assembly, electrospinning, plasma treatments, sol-gel, etc. Studies [68][69][70][71][72][73][74][75][76][77] have aimed at providing low surface energy (using fluorine or silicon-containing molecules; for rough surfaces) and high micro-nanostructure surface roughness (by the introduction of pores or microstructure; for non-rough surfaces) [63,78]. Surface energy is associated with the intermolecular forces between two media interfaces. ...
Transformers play an essential role in power networks, ensuring that generated power gets to consumers at the safest voltage level. However, they are prone to insulation failure from ageing, which has fatal and economic consequences if left undetected or unattended. Traditional detection methods are based on scheduled maintenance practices that often involve taking samples from in situ transformers and analysing them in laboratories using several techniques. This conventional method exposes the engineer performing the test to hazards, requires specialised training, and does not guarantee reliable results because samples can be contaminated during collection and transportation.
This paper reviews the transformer oil types and some traditional ageing detection methods, including breakdown voltage (BDV), spectroscopy, dissolved gas analysis, total acid number, interfacial tension, and corresponding regulating standards. In addition, a review of sensors, technologies to improve the reliability of online ageing detection, and related online transformer ageing systems is covered in this work.
A non-destructive online ageing detection method for in situ transformer oil is a better
alternative to the traditional offline detection method. Moreover, when combined with the Internet of Things (IoT) and artificial intelligence, a prescriptive maintenance solution emerges, offering more advantages and robustness than offline preventive maintenance approaches.
... The plasma based approaches are widely used for cleaning, surface activation, improved adhesion, anti-corrosion, and to develop a large variety of functional coatings [282][283][284][285][286][287][288]. In medicine, plasma treatment is now replacing the long-used laser technology for wound management, tumour treatment, tissue engineering and is also extensively used in bio-decontamination and sterilization [289]. ...
... The process can be easily adopted in large-scale industrial applications due to the adaptability of an atmospheric pressure plasma jet system. [288,320] Flouroalkylsilanes (FAS) ...
Solar energy-based devices are protected using glass surfaces that need to be cleaned periodically to maintain their desired optimum performance. If these devices are large and placed in remote locations or not easily accessible, manual cleaning is not only difficult but prohibitively expensive, which in turn necessitates suitable self-cleaning coatings to be applied on the glass surfaces. Traditionally, sol-gel processes have been used for such coating developments. However, for large volume production, spray based processes have certain advantages, especially their lower cost and ease of manufacturing. The self-cleaning coatings can be either hydrophobic or hydrophilic determined by the contact angle between water and glass surfaces. Further, care must be taken when selecting coating materials and the corresponding coating parameters to maintain the transparency or reflectivity of such glass surfaces used for the particular device applications. The optical transparency of self-cleaning or anti-soiling coating is of paramount importance in the case of solar photovoltaic panels and related solar devices. Therefore, enhancing their performance by additional cost-effective anti-reflecting coatings, is a plausible solution. A state-of-the-art of this effort is being attempted in this review. It includes the necessary basic principles, cost-effective deposition techniques, performance evaluation standards and life expectancy of such coatings. The scope of the present review has been broadened by including specific issues related to concentrated solar power devices and by highlighting recent advances in atmospheric pressure plasma deposition processes. Additionally, use of non-fluorinated polymer materials and related nanostructured materials has been suggested for the fabrication of the self-cleaning coatings.
... The plasma treatment process follows plasma etching and thus is classified as a top-down fabrication method where selective removal of the materials from a surface is carried out using plasma radicals that are reactive or inert in nature. Here, the plasma follows a reaction with some atoms [27,80] or phases of a surface by which the by-products are ejected out in a gaseous form from the surface. In various expositions, the plasma treatment is followed after the lithography and templating process, whereas in some other cases, the process is used before lithographic processes [81]. ...
The self-cleaning mechanism attribute of organic surfaces is grabbing much attention in most of the commercially available commodities. Among organic surfaces, investigations on hydrophobic surfaces are much insightful and intriguing. The self-cleaning phenomena of hydrophobic surfaces are also known as the lotus effect. The effect uses the right combination of roughness and surface chemistry, which makes high contact angle of water droplets on a surface, making the quick roll-off of the water droplet from the surface, also picking up the dirt on its way. Thus, the plant leaves surface wetness has many ecological and physiological consequences, and its extent and duration can be affected by the leaf surface containing morphological structure, which contributes to the ecosystem interception rates. In this review, we have described the causes and behaviour of phyto-based hydrophobic surfaces. Furthermore, the applications of various phyto-based hydrophobic surfaces, either by implementing directly or by mimicking micro-/nanostructures of the surfaces, have been illustrated. Lastly, the methods for fabricating the artificial super-hydrophobic surface by mimicking the phyto-based natural hydrophobic surfaces, precisely by following the top-down, bottom-up, and hybrid approaches, have been explained. This article could benefit scientists and researchers currently working on phyto-based super-hydrophobicity fields.
Graphical abstract
