Introduction and Industrial Applications Nano Oleophobic Coating

Transcription

1 International Journal of Nanoscience and Nanoengineering 2018; 4(2): Introduction and Industrial Applications Nano Oleophobic Coating Pouresmaeily Seyed Mohammad 1, *, Bayaz Parisa 2, Hadavand Shirkavand Behzad 3, Golamreza Rezaei Behbehani 2 1 Department of Chemistry & Chemical engineering, Malek-e-Ashtar University of Technology, Tehran, Iran 2 Department of Chemistry, Imam Khomeini International University, Qazvin, Iran 3 Institute for Color Science & Technology, Tehran, Iran address * Corresponding author To cite this article Pouresmaeily Seyed Mohammad, Bayaz Parisa, Hadavand Shirkavand Behzad, Golamreza Rezaei Behbehani. Introduction and Industrial Applications Nano Oleophobic Coating. International Journal of Nanoscience and Nanoengineering. Vol. 4, No. 2, 2018, pp Received: March 5, 2018; Accepted: March 27, 2018; Published: June 5, 2018 Abstract Surface of accessories around us at risk of infection of contacts or deposition of liquids, fat, dust and keep them clean is timeconsuming and expensive. Fat pollution is one of the most serious challenges among the manufactures of home appliances and electronics [1]. On the other hand, cleaning the saturated fat frequently requires using chemical detergents that are harmful to the environment. So using oleophobic coatings on the surfaces in addition to reducing time and costs helps environment [2-4]. Keywords Nano Oleophobic Coating, Applications, Review 1. Introduction To Many levels in nature, such as leaves of various plants, the desert beetle wings, blue gecko foot surface is hydrophobic. Thus, the nature facing the researchers many ways to study of the chemical composition and physical parameters of surfaces, such as surface tension energy and the surface hardness to control, design and synthesis of surfaces with contact angle of more than 150o and super oleophobic and hydrophobic properties [5]. Due to the lower surface energy of oil than water, expected surfaces wet by water, can wet by oil. So all of the oleophobic surfaces could change to hydrophobic surface. Engineering the oleophobic surfaces is harder than hydrophobic surfaces because of ultralow surface tension of the oil molecules [6-8]. Excretion of liquids depends on chemical and morphological parameters of surfaces. To creating surfaces with super oleophobic and hydrophobic properties and over than 150oc contact angle requires hard surfaces with low surface energy that for producing the low contact energy surfaces. It should be coat the base with chemical compounds that has low contact energies. 2. Review the Synthesis Methods One of the most common methods is using Fluorine compounds for improving surface hardness or using Nano particles morphological for improving hydrophobicity and oleophobicity properties. Also studies has shown that using Fluorine containing compounds with special surface structures (T-shape or Mushroom-like structures) to reaching oleophobic properties is more ideal [9-11]. Studies are showing that which type of surfactants cause more reduction in surface tension or difference rate of applying this surfactants. So studying surface tension of different materials helps to reaching our purposes. In last two decades, super hydrophobic and super oleophobic surfaces in filtering (oil and water separation) has been considered [12]. Therefore Jiang group, succeed in synthesis a thin layer of super hydrophobic and super oleophobic coating by spraying an emulsion solution on a surface. Also Jiang and his coworkers could present a synthesis method of one-layer and multi structure with these

2 25 Pouresmaeily Seyed Mohammad et al.: Introduction and Industrial Applications Nano Oleophobic Coating properties. Teo and coworkers also succeed in synthesis of corrected coating layer with considered properties on steel surfaces. Wang and coworkers also succeed in strengthening copper surface by electrochemical deposition than oil and water absorption [13-15]. Hoyang and research teammates succeed synthesis a super oleophobic layer with over 130o of contact angle olive oil and over 150o contact angle than water drops by using Fluorinated Alkyl Silanes in 2006 [16]. Janiping and Stephen Seager designed a super oleophobic coating by Silicon filaments [17]. Lakshmi presented Nano sol-gel multi-structures super oleophobic coatings improving oleophobicity property by means of Induced Meta acrylic fluorine alkyl copolymers and silica Nano particles. This method has been introduced as a simple and effective method for creating multi usage hydrophobic, oleophobic, and selfcleaning surfaces on different beds like glass, metal and ceramic [18-20]. Figure 1. Schematic showing the wetting mechanism of a liquid droplet on a solid surface in vapor or under another liquid. (a) A liquid droplet on an ideal flat lyophobic solid surface in vapor. A liquid droplet on a rough lyophobic solid surface in a wet-contact state (b) or a non-wet-contact state (c) in vapor. (d) A liquid droplet on a rough lyophilic solid surface in vapor. (e) A liquid droplet on a rough lyophobic solid surface in a transition state in vapor. (f) A droplet of liquid (L1) on a solid surface under another liquid (L2). 3. Manufacture Transparent hydrophobic and oleophobic coatings of this kind can be manufactured using sol-gel processes. In simple terms, the raw materials are so-called silanes with a silicon base atom which can be modified by adding certain chemical substances to it (e.g. fluorine compounds) in order to retain the required properties. Nano scale particles (colloids) are produced from the silanes by means of chemical reactions in a solution. The dispersion of particles is called the sol. Depending on the type of sol chosen, the solution evaporates either at room temperature or when it is heated, and the sol becomes a viscous gel because the particles concatenate into a dense web due to their high reactivity. Once it has dried out a compact layer is formed. The sol-gel process was developed as early as the 1930s, but for some years now has been ascribed to chemical nanotechnology. Figure 2. Diagram of an Easy-to-Clean surface. The sol can be applied to a great variety of surfaces using traditional industrial processes such as dip coating, spraying or spin-coating. The resulting coatings are only a few nanometers thin and transparent an important advantage over other traditional coating materials such as Teflon, which has a dark color because of its graphite content. These coatings can consequently also be used on, for example, glass. Sol-gel processes are already used in the motor vehicle industry to produce water-repellent coatings for windscreens or exterior mirrors. In industrial manufacturing processes the coating is burned into the surfaces at high temperatures, thereby increasing their durability. As a sol can also dry out

3 International Journal of Nanoscience and Nanoengineering 2018; 4(2): at room temperature to form a firm layer, surfaces such as window glass can also be treated postproduction by the consumer or a commercial service provider (e.g. cleaning companies). A number of different liquids or sprays for this purpose are commercially available. These coatings however are not durable and need to be renewed after a certain period of time. Unfortunately, information regarding the exact constituents of post-production applications with "Easy-toClean" properties which can be obtained in shops or via the internet is scarce as the manufacturers often claim the right of trade secrecy. It is therefore usually impossible to establish whether products are based on chemical nanotechnology in each case. Impregnating agents are also available which make textiles and leather dirt and water- repellent and which, manufacturers claim, contain nanoparticles or are based on nanotechnology. Often, however, traditional surfactant substances are used, such as fluorocarbon resin or silicon oils, which produce a Nano scale impregnated layer. Based on the current understanding of nanotechnology, onedimensional nanostructures would probably also be categorized as such, however it appears that many products do not fulfill an essential criterion of nanotechnology i.e. that the material has new properties. Nonetheless there are still impregnating materials on the market which manufacturers claim, with reference to the lotus plant, produce surface roughness and hydrophobia on materials by means of nanoparticles, making them dirt and water-repellent. Self-cleaning II photocatalytic Nano titanium dioxide (TiO2). To date, photocatalytic self-cleaning is probably the most wide-spread application ascribed to nanotechnology in the construction industry. There are already a great number of buildings worldwide which have been treated with it. The photocatalytic properties of TiO2 were discovered as long ago as 1967 by Akira Fujishima, a scientist at the University of Tokyo, and the phenomenon became known as the "HondaFujishima Effect". The first house with self-cleaning exterior surfaces was Fujishima's own. Titanium dioxide is hydrophilic due to its high surface energy, hence water does not form drops on a surface coated with it, but a sealed water film instead. A coating of this kind hence behaves in exactly the opposite manner to a surface whose self-cleaning properties are based on the "Lotus-Effect". It is also transparent and can therefore also be used on glass. In addition, TiO2 is photocatalytic, in other words in the presence of water, oxygen radicals are produced under UV light irradiation which in turn can decompose organic material such as, for example, fats, oils, soot or plant materials. TiO2 is especially reactive in nanoform. It is not expended during catalysis, with the result that the effect is lasting. On self-cleaning surfaces of this type organic dirt is dissolved in the water film, decomposed, and the residue is removed by the next heavy shower of rain. This does not however mean that surfaces of this kind must never be cleaned. The amount of dirt is merely reduced so that it does not need to be cleaned as often. From an engineering point of view coating organic or polymer surfaces (e.g. plastics) with 26 TiO2 is complicated because the carrier materials themselves, like any other organic material, are attacked and destroyed by oxidation. In order to prevent this, inorganic barrier layers need to be applied and the TiO2 nanoparticles given a surface coating in order that the different layers adhere to each other. Photocatalytic self-cleaning only works in outdoor use because it requires UV light and water to remove the residue. Ways of modifying the properties of TiO2 are currently being researched so that it becomes photocatalytic by irradiation with visible light. This is achieved by doping them with metal atoms such as, for example, chromium, vanadium, tungsten or carbon. The results of earlier research have already been implemented in commercial products such as photo catalytically active interior paints which reduce gaseous pollutants in the air, for example to improve the air quality in enclosed office spaces. As photo catalysis can also kill microorganisms, it is conceivable that antimicrobial coatings may be produced in the future, for example for use in clinical areas, and this is now being researched. The ultrathin water film formed by the hydrophilic properties of the Nano scale titanium dioxide on surfaces additionally prevents glass from misting up since water droplets cannot form. The "Anti-Fog" effect, as it is known, is particularly beneficial, for example, in glass surfaces in conservatories, exterior mirrors on motor vehicles, or even in bathroom mirrors or spectacles. Manufacture Photocatalytic coatings with nano-tio2 are usually applied at the same time as the material itself is manufactured, using Chemical Vapor Deposition (CVD). The coating is already in use not just in glass surfaces, but also in plastics (PVC), sound-proofing panels, tiles, roof tiles or concrete slabs. However by this method it is not possible to coat these materials post-production. In the case of glazing, it is important to ensure that silicon seals are not used as their oils seep over the glass, destroying the hydrophilic surface properties and leading to unsightly smears forming. Figure 3. Hydrophilic coating (right) with TiO2 on float glass. As well as coating by means of CVD, sol-gel processes can also be used to create the surface functionality, for

4 27 Pouresmaeily Seyed Mohammad et al.: Introduction and Industrial Applications Nano Oleophobic Coating example in motor vehicle windscreens or exterior mirrors. This latter method is far more preferable for the manufacturers as it is carried out at lower temperatures, takes less time, and saves energy costs. House paints with photo catalytically active TiO2 nanoparticles are also available, which not only have self-cleaning properties but which also reduce nitrogen oxide and ozone. Effective parameters on oleophobicity property. Nano particles size and type, oil viscosity and drops type and molecular weight are parameters that effect on oleophobicity property. But length of the fluorine surfactants chain doesn t have an effect on oleophobicity property. compatibility. Figure 5. (a) Scanning electron microscope image of electrospun film prepared from 4 wt% PS/DMF solution; (b) Behavior of a water droplet on its surface. CA = Conclusion Water and oil repellency from surfaces is one of important aims for researchers and producers in different industries. Oleophobic surfaces uses in wide fields such as: oil and water separation in oil industry, electronics, medical instruments, anti-corrosion coatings, textile Industry, antifinger print glasses and etc. In addition to oleophobicity properties of this coatings can point easy cleaning, anti fog and dust properties. So liquids excretion from different surfaces has been found a special rank in life and industry and synthesis of oleophobic coatings is important. Figure 4. SEM images of the copper wafer surfaces etched under different conditions: (a) 5 M HNO3; (b) 5 M HNO3 under ultra-sonication; (c) 5 M HNO3 with 1.2 mm CTAB; (d) 5 M HNO3 with 1.2 mm CTAB under ultrasonication. All the etching time is 20 min. References [1] Gau, H. Hemminghaus, S. Lenz, P. Oleowsky, R. (1999), Liquid Morphologies on Structured Surfaces: From Microchannels to MicrochipS, science DOI: [2] Steele, A. Bayer. I and Loth. E. (2009), Inherently Superoleophobic Nanocomposite Coatings by Spray Atomization, The Journal of American Chemical Society, 9, 14. [3] Yan. H, Kurogi. K, Tsujii. K. (2006), High oil-repellent poly (alkylpyrrole) films coated with fluorinated alkylsilane by a facile way, The Journal of American Chemical Society, [4] Darmanin, T and Guittard, F. (2014), Enhancement of the Superoleophobic Properties of Fluorinated PEDOP Using Polar Glycol Spacers, The Journal of Physical Chemistry, 118, [5] Tuteja, A and et (2007), Designing Superoleophobic Surfaces, Science 318, DOI: [6] Zhou, X. Hong, En, L. Renbi, B. (2013), A novel membrane showing both hydrophilic and oleophobic surface and its nonfouling performance for potential water treatment applications, The Journal of membrane science, 436: [7] Howarter, J. (2008), Hydrophobic-oleophobic stimuliresponsive materials and surfaces, Thesis (Ph.D.), Purdue University, B 5535; 123 p. 4. Industrials applications Producing oleophobic compounds is so important because of applications in life an industry. Oleophobic surfaces uses in wide and different fields for example, in optics for producing high resolution glasses, using oleophobic coatings that cleaning and maintaining get easier. In electronics. Oleophobic coating cause anti-finger point effects on touch screens and improving quality. In addition, oleophobic surfaces could considerable effects in electronics applications such as metal oxides, polymers, ceramics and sensitive parts such as: printer heads, electronic circuits and stainless steels. This technology could be useful as a preservative coatings in medical, dental and surgical instruments and any other surfaces that is in contact with doctors, patients and staffs that prevents growing dangerous bacteria. Also this technology could be used in producing self-cleaning and antidepose pipes. In addition creating smooth anti corrosion surfaces is one the other this technology achievements that use in specific weather conditions like coastal cities to build docks, ports, bridges in shipbuilding industry. Also using coatings in different surfaces of home appliances, cause saving costs and time in long times considerably. The most important advantages of these coatings is environment

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