The hydrophobic cotton surface is easily fabricated by a new and simple method through the adsorption of fluorosurfactant on the cotton surface and then the polymerization of fluorine monomer at low surface energy in the presence of an initiator at room temperature in a short time. By in situ introducing a fluoropolymer onto cotton fibers to generate a double-dimensional surface roughness, followed by hydrophobization with trifluoroethyl methacrylate (TFEM), normally hydrophilic cotton was easily transformed into hydrophobic, exhibiting a static contact angle with water of 132° for a 10 µL droplet and even water droplets can easily roll off the cotton surface. The micro/nanostructured rough surface morphology, after surface fluorination, results in simultaneous hydrophobicity and superoleophilicity. The hydrophobic character was confirmed by a simple drop test and contact angle measurement. The surface composition was evaluated by FT IR and SEM, EDS analysis to confirm the fluoropolymer layer on the cotton surface. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Inspired by the lotus phenomenon, the construction of such special superhydrophobic surfaces (the contact angle with water is greater than 1500) is increasingly attractive in various potential application fields in both academic research and application practical as self-cleaning, anti-contamination and non-stick. Superhydrophobicity is extraordinary wettability with high water contact angle and low slip angle. Nienhuis et al elaborated that the water droplets rolling on the surfaces of lotus leaves are due to the presence of a combination of rough micro-nanostructure and low surface energy waxy materials on their surfaces. Based on this principle, scientists and researchers have attempted various methods to fabricate such special hydrophobic and superhydrophobic surfaces by constructing hierarchical micro/nanostructures with low surface energy materials. Cotton, a soft and fluffy fiber, has low production costs, low density, good strength in both wet and dry and other unique properties such as comfort and breathability make them even more attractive for future applications. It is a raw material that has been widely used to make garments for many years. Cotton is composed of nearly pure cellulose that contains hydroxyl groups. Despite the many advantages of cotton, the hydroxyl groups make it an excellent water-loving, i.e. hydrophilic, absorbent. Excessive water absorbency allows cotton fabric to stain and get dirty easily. Sometimes cotton fabrics are also wet and contaminated with blood, oily appearance and even bacteria which are unwanted in their use as cloths, especially in the hotel industry. Therefore, in recent years, non-wettable cotton fabrics with a high water contact angle and dirt-resistant cotton fabrics have long been an interesting topic in research. Modifying fabrics with hydrophobic chemicals to make the surface hydrophobic is an established technology developed in the early 1940s (Roach et al. al. 2008). For example, a patent published by Gao and McCarthy et al (2006) based on silane hydrophobization. They have been successfully manufactured from lotus leaf-like artificial polyester fabric. Two factors, the chemical composition of the surface and the surface structure (roughness), favor the special non-wettable effects on fabrics. Several approaches have been reported to improve thesurface roughness, such as the introduction of nanotechnology through electrospinning, plasma treatment and sol-gel technology, chemical vapor deposition. The silicone compound has also been reported to coat fabric surfaces for many years. In addition to nanotechnology, polymer technology also plays an important role to create a thin surface film with high hydrophobic character. Fluorocarbon coating was employed to achieve water repellency of the wells as studied by Shao et al (2004) and others. A new method to produce a thin-film polymer coating on a solid substrate via surfactant adsorption, called admicellar polymerization, has recently been employed. It is a surfactant-assisted polymerization to coat cotton fabric by forming an ultra-thin film with a thickness of the order of 10 nm, i.e. in nanoscale finishes, without changing the softness and breathability characteristics of cotton fabrics. Admicellar polymerization is a useful method for creating ultrathin polymer films on solid surfaces in an aqueous solution. The micellar process is the formation of a double layer of surfactant on a solid surface where adsorption occurs. After the addition of monomers into the bilayer, the monomers will partition into the cell nucleus admicelle in a process called adsolubilization. Then, in the presence of an initiator, this monomer undergoes a polymerization reaction forming a high monomer density region at the water/substrate interface to form a thick or thin polymer layer on the surface substrate. Finally, the substrate is rinsed to wash away excess surfactant and expose the polymer layer on the surface of the substrate. The schematic representation of admicellar polymerization on solid substrate is shown in Fig. 1. CMC plays an important role in surfactant aggregation. A lower CMC means a low concentration and less surfactant will also be needed for adsorption at the solid/liquid interface for admicellar polymerization with lower costs. Wu et al. studied the formation of ultrathin polystyrene films on alumina by this technique using sodium dodecyl sulfate (SDS) as a surfactant. Esumi et al. also created a surfactant-coated alumina with particle size of 200 nm by admicellar polymerization technique using a polymerizable surfactant. Admicellar polymerization has been successfully employed to create various types of polymer films on different surfaces such as polystyrene on silica, polystyrene on cotton, fluoropolymer on alumina. Admicellar polymerizations have superior advantages over the above process due to its simplicity with low energy consumption when used on fabrics (E .A. O' Rear et al. 2002). The fluorosurfactant contains a hydrophilic tail and the hydrophobic headgroup has specific properties such as low polarizability, low dielectric constant, high vapor pressure, high gas solubility, low surface tension and also low critical micelle concentration [20]. In addition to this, both fluorocarbon and fluorosurfactant have stronger hydrogen bonding and also larger partition coefficients, higher surface activity than the minimum amount of the hydrocarbon system and lower concentration are required. Below are approaches to create a dual-phase hydrophobic cotton fabric by adsorption of a small amount of fluorosurfactant and solubilization of a small amount of fluoromonomers using the admicellar polymerization technique. Small quantities are criteriavery important to overcome the high cost efficiency of fluorochemicals. Materials The cotton pique fabric was purchased from the local textile shop. The fabric was scaled and treated in 10% NaOH solution for 1 hour and then the fabric was washed repeatedly until it was free of any residual lubricant and other additives. The used monomer 2,2,2-trifluoroethyl methacrylate (TFEM) was purchased from Sigma Aldrich. The surfactants used are non-ionic fluorosurfactant FS61 purchased from DuPont India. The initiator potassium persulfate was purchased from Merck. All chemicals were used without further purification. Surface modification of cotton fabrics by admicellar polymerization The modification was performed by the admicellar polymerization method via adsorption of surfactant on the surface. A variety of sample formulations were performed using the trial-and-error method. We have described the sample formulation method with the best results. Homopolymerization of 1 ml of 3 mM TFEM on cotton was carried out in a 30 ml vial containing a 20 ml solution of FS61 (1 ml) at CMC, pH-4 water at temperature 400°C. 1%NaCl is used for better absorption of the surfactant. At the beginning of the experiment, 1 g cotton fabric was placed in the vial; the vial was sealed with aluminum foil. The sealed vial was then placed in a 400°C thermostated water bath and shaken at 80 rpm for 1 hour. Then an initiator potassium persulfate was injected to initiate the polymerization to give an initiator:monomer ratio of 1:1. The vial was resealed and polymerization was allowed to proceed for another hour at 600°C. The excess surfactant was washed away with different volumes of water and the sample was dried in an oven at 700°C. Determination of Hydrophobic Properties Drop Test The water repellency test is an initial characterization of the treated surface to evaluate the hydrophobic coating on the cotton surface. Two test methods were used to evaluate water repellency. An initial characterization of the treated surface took place through the drop test. A 10 µL drop of distilled water was carefully placed on the surface of the cotton fabric without force with a 20 µL syringe. The water absorption time (wetting time) on the fabric surface in the drop test was determined up to a maximum of 120 minutes, after which the sample passed. A second best method was performed according to AATCC test method 22 (spray test). Contact angle measurement Water contact angles were measured using an automatic optical tensiometer for video contact angle testing (TL100 Theta) and software provided with the instrument at a temperature of 240°C. The contact angle was measured by the sessile drop method. For contact angle measurement, a 10 µL drop of distilled, deionized water with surface tension of 72.75 mN/m was deposited onto the tissue using a micropipette from a height of 2 cm. The observations occurred over a 10 minute period and the average contact angle was reported by measuring at five different sample sites on both cotton fabric sites. The average contact angle was obtained in 1320. Characterization of Fluoropolymer-Coated Cotton Fabrics For the surface morphology of the modified and unmodified cotton fabric was observed in a scanning electron microscope (SEM) model no. JEOL JSM 5800 scanning microscope. All samples were gold-plated before scanning. The SEM imagesindicate the surface micro/nanostructure. For chemical composition, EDS analysis was also performed using a ZEISS 960A SEM equipped with Oxford Link energy dispersive spectroscopy. The FTIR spectra of the unmodified and modified cotton fabric were recorded by ATR mode technique using PerkinElmer FTIR-ATR spectrophotometer (L1600300 Spectrum two Lita SN96499). The IR spectrum was detected in the wavenumber range of 4,000 cm-1–500 cm-1. This study explains the features present in different untreated and treated cotton fabrics. Hydrophobic Properties of Coatings Hydrophobicity on cotton surfaces cannot be assessed by just one method. The drop test and water residence time allow for a quick and easy presentation of the fabric's water-repellent properties due to the formation of the continuous thin polymer film on the surface of the cotton. To ascertain the water repellent characteristics of the fabric samples, the performance was evaluated using drop tests, spray tests and contact angle measurements to gain a comprehensive understanding of the performance. The drops on both surfaces of the cotton surface in Fig. 3 and rolls of water in Fig. 4 form spheres (also shown in Supporting Information Video 1) on the cotton surface may demonstrate that a hydrophobic film has been created on the surface and prevents water or moisture from penetrating through the surface. Hydrophobicity is related to the contact angle of the surface. It is the angle formed when a drop rests on a solid (flat) surface and is surrounded by a gas. A better measurement of the contact angle with the 1320 water droplets shown in Fig. 2 was obtained, and the residence time of the water droplets on the cotton surface was 120 minutes. This high contact angle indicates the weak interaction between water and the cotton surface exposed the conversion of a hydrophilic surface into a hydrophobic surface. On the other hand, octane, a liquid with low surface tension (?lv = 21.62 mN/m), rapidly spreads on the coated fabric in less than 10 seconds indicating its super oleophilicity. This is because oil has a lower surface tension than water. Additionally, chloroform adsorption was performed to examine the use of the fabric with an organic solvent having densities higher than that of water. When the piece of hydrophobic fabric was brought into contact with water to get close to the chloroform, the drop of chloroform could be instantly sucked up by the fabric under water. Furthermore, a bright, shiny and transparent surface could be observed under the water droplet in Fig. 3, which was an observation of trapped air and the creation of a composite solid-liquid-air interface. All the above-mentioned results indicated stable hydrophobicity on the cotton surface. Surface Morphology and Chemical Composition SEM images are a useful complement to contact angle to provide surface morphology on modified cotton samples. SEM imaging reveals that the hydrophobic behavior of the cotton substrate is a result of the rough hierarchical structure. Inspired by natural surfaces (e.g. lotus leaves, butterfly wings), different types of artificial surfaces have been designed and created. The surface microstructure and composition of lotus leaves were studied by Neinhuis and collaborators. Nienhuis and collaborators studied the micromorphological characteristics and demonstrated that water repellency is based on surface roughness caused by different microstructures (trichomes, cuticular folds and wax crystals). Water on solid surfaces is mainly in contact with air pockets.