Fluorinated Alkyl Silane Research Articles

Water-solid triboelectrification with self-repairable surfaces for water-flow energy harvesting

A new repairable water-solid triboelectric nanogenerator (W-TENG) based on superhydrophobic surface is fabricated to harvest water-flow energy. The superhydrophobic triboelectrode with micro- and nanostructures is prepared by adhering polyvinylidene fluorid (PVDF) nanospheres to a polyimide (PI) film through a double-sided adhesive tape followed with a fluorination process. When water flows through the superhydrophobic surfaces with a flow rate of 0.3 m/s, the W-TENGs array could easily harvest water-flow energy to obtain a current output of 20 μA which can light more than 30 commercial LEDs or be used for self-powered sensors to detect concentration change of chemicals pollutants in water. More importantly, when the superhydrophobic surface is damaged during long-term working, it could be self-repaired by releasing the fluorinated alkyl silane packed in pores of adhesive tape surface, and a self-repairable W-TENG is achieved. Given its easy fabrication and self-healing properties, the W-TENG and W-TENGs array have promising practical use in oceans and rivers energies harvesting, especially in some remote areas, for early warning, indicator light and self-powered detection sensors.

Preparation of self-healing hydrophobic coating on AA6061 alloy surface and its anti-corrosion property

Hydrolyzed fluorinated alkyl silane (FAS) containing well-dispersed fluorinated-decyl polyhedral oligomeric silsesquioxane (FD-POSS) was used to form a thin coating layer on AA6061 alloy. Its performance was evaluated by the electrochemical measurements and surface analysis technology. The FD-POSS/FAS film shifted the corrosion potential (Ecorr) of AA6061 alloy to a positive value, and suppressed significantly the anodic and cathodic corrosion reactions. Corrosion current density was decreased by one order of magnitude after FD-POSS/FAS coating treatment. The coating was hydrophobic with a water contact angle of 130°. It was highly transparent and had excellent stability and reasonable adhesion with AA6061. The coating also showed a remarkable self-healing ability to auto-repair from both chemical and physical damages. This self-healing FD-POSS/FAS coating may provide an effective protection toward aluminum alloys for power transmission applications.

Vapor–Liquid Deposition Strategy To Prepare Superhydrophobic and Superoleophilic Graphene Aerogel for Oil–Water Separation

The problems of high temperature and volume shrinkage are frequently encountered in the process of fabricating superhydrophobic graphene aerogels. We present ultralight graphene aerogels with superhydrophobicity and superoleophilicity by a vapor–liquid deposition process. The graphene aerogels are prepared by graphene oxide assembled into monolithic graphene hydrogel in dopamine-mediated aqueous solution at mild temperature and a sealed reaction, then by directional freezing and freeze-drying. Subsequent fluorinated alkyl silane is introduced to produce ultralight graphene aerogel by vapor–liquid deposition treatments; the surface of the aerogel has outstanding superhydrophobicity and superoleophilicity with water and oil contact angles of 160.2° and 0°, respectively. In addition, the resulting graphene aerogels showed super low density, large specific surface area, excellent adsorption capacities, and superior adsorption recyclability. Its adsorption capacity was higher than 109 g/g for the used common o...

Fabrication of highly transparent slippery surfaces with omniphobicity by an improved process using non-solvent-induced phase separation

A facile nanoscale phase separation method has been proposed for the fabrication of slippery liquid-infused porous surfaces (SLIPSs). This method, however, suffered from the fact that high transmittance was unable to be achieved because it was difficult to control the surface roughness, film thickness, and optical properties. Moreover, membrane prepared by this method exhibited a low surface roughness, and organic droplets stuck to the SLIPSs prepared in several conditions. In this work, an improved process emphasizing the fluorinated alkyl silane (FAS) modification of poly(vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) was developed for the fabrication of competent SLIPSs. By using an aminosilane and a fluorinated alkyl silane in the first and the second modification steps, respectively, the hydrophobicity of the copolymer was shown to be effectively enhanced. Much better and reproducible SLIPSs can then be fabricated by the extremely simple process using non-solvent-induced phase separation (NIPS) of PVDF-HFP/di-n-butyl phthalate (DBP) solutions. The as-fabricated SLIPSs exhibited extreme liquid repellency as signified by very low sliding angles (less than 4° for droplet volume of 5 μl) against seven pure liquids (water, pentadecane, nonane, octane, heptane, hexane, and pentane) with surface tension values ranging from 72.8 to 17.2 mN/m. Furthermore, high optical transmittance (average transmittance = 92.9%) of the self-standing omniphobic thin film may find its applications among others in self-cleaning solar cells with minor deterioration in their conversion efficiency.

A Waterborne Coating System for Preparing Robust, Self‐healing, Superamphiphobic Surfaces

Existing coating systems for preparing superamphiphobic surfaces are predominantly confined to small‐scale uses due to the heavy use of organic solvents. Waterborne coating treatment is highly desirable for the high safety, low cost, and nonenvironmental impact, but it remains difficult to develop due to the problems in forming durable, homogeneous coating from an aqueous dispersion of amphiphobic substances. In this study, the authors have proved that lyophobic nanoparticles, fluorinated alkyl silane (FAS), and fluorocarbon surfactant can form a stable dispersion in water, suitable for preparing durable superamphiphobic surfaces on various solid substrates. A series of substrates including fabrics, sponge, wood, glass, and metal, after being coated with this ternary coating system, shows superamphiphobicity with low contact angle hysteresis. The coating is durable enough against physical abrasion, repeated washing, boiling in water, and strong acid/base attacks. Benefiting from FAS, the coating also has a self‐healing ability against both physical and chemical damages. The unexpected stability of the ternary dispersion is a result of the synergistic interaction of the three ingredients. Results from this study may promote the wide development of safe and cost‐efficient superamphiphobic techniques for diverse applications.

Superhydrophobic and luminescent cotton fabrics prepared by dip-coating of APTMS modified SrAl2O4:Eu2+,Dy3+ particles in the presence of SU8 and fluorinated alkyl silane

An organic-inorganic composite dip-coating method was adopted in order to obtain ideal water repellent cotton fabrics. To be specific, a dual-functional coating with both superhydrophobic and luminescent properties was prepared on cotton fabric by using a dip-coating solution comprising (3-aminopropyl) trimethoxysilane (APTMS) modified SrAl2O4:Eu2+,Dy3+ particles, SU8, and fluorinated alkyl silane (FAS). The micro/nano-scale roughness generated by SrAl2O4:Eu2+,Dy3+ particles, together with low-surface-energy FAS, rendered the cotton fabric superhydrophobic with a water contact angle of about 160° and a sliding angle as small as 2°. The coated fabric could withstand at least 100 cycles of standard laundry. The emission spectra of the coated fabric showed two emission peaks at 440 and 520 nm, which belonged to the blue and yellow-green color areas, respectively. The afterglow duration of the coated fabric was mainly influenced by the different depths of the trap levels in the SrAl2O4:Eu2+,Dy3+.

Fabrication of microwave absorbing CoFe2O4 coatings with robust superhydrophobicity on natural wood surfaces

A superhydrophobic wood surface with microwave absorption property was prepared based on the formation of CoFe2O4 nanoparticles and subsequent hydrophobization using fluorinated alkylsilane (FAS). Meanwhile, sticky epoxy resin was worked as a caking agent by adhering abundant of CoFe2O4 nanoparticles to wood surface. The as-prepared superhydrophobic coatings on wood maintain stable superhydrophobicity after suffering a significant abrasion. Moreover, the complex permeability and permittivity of the coated wood composites were measured in the frequency range of 2–18GHz by vector network analysis. The microwave absorption properties were elucidated by the traditional coaxial line method. The results show that the as-prepared wood composites have excellent microwave absorption properties at the frequency of 16GHz, and the minimum reflection loss can reach −12.3dB. The approach presented may provide further routes for designing outdoor wood wave absorbers with a specified absorption frequency.

Sol–gel preparation of fluoro-containing ORMOSIL antireflective coating with resistance simultaneously to hydrophilic and oleophilic pollutants

Fluoro-containing ORMOSIL (organically modified silicate) sols were prepared by a one-pot sol–gel Stober route by co-condensation of tetraethylorthosilicate (TEOS) and fluorinated alkyl silane [1H, 1H, 2H, 2H-perfluorodecyltriethoxysilanes, (POTS)] using isopropanol as dispersant and ammonia as catalyst. Antireflective (AR) coatings from these sols were prepared by dip coating. It was found that isopropanol not only played as dispersant but also grafted to the surface of colloidal silica particles, and therefore gave the fluoro-free AR coating an almost superhydrophobic property. By increasing the molar ratio of POTS to TEOS, the oleophobicity of AR coatings increased gradually. As the molar ratio of POTS to TEOS is 0.05, the AR coating had the advantages of excellent hydrophobicity, improved oleophobicity and high transmittance. The water, CH2I2 and polydimethyl siloxane contact angles are 143°, 119° and 85°, respectively. The water contact angle was further increased to be higher than 150° by a further surface hydrophobic modification with hexamethylisilazane. The coated glass substrates (BK-7) had very high transmittance of up to 99.8 % at a determined wavelength and had good AR stability to the hydrophilic and oleophilic pollutants. By exposing to humid environment (about 95 % humidity) for 2 months, the transmittance of fluoro-free AR coating decreased from 99.9 to about 99.5 % while that of superhydrphobic and oleophobic AR coating decreased from 99.8 to 99.6 %. Being placed in a vacuum chamber which had organic pollutants volatilized from vacuum pump oil, the transmittance of fluoro-free silica AR coating decreased seriously from 99.9 to 97.8 % while that of fluoro-containing ORMOSIL AR coating decreased slightly from 99.8 to 99.1 %. Fluoro-containing ORMOSIL antireflective coating with resistance simultaneously to hydrophilic and oleophilic pollutants was prepared by sol–gel process.

Dual‐Layer Superamphiphobic/Superhydrophobic‐Oleophilic Nanofibrous Membranes with Unidirectional Oil‐Transport Ability and Strengthened Oil–Water Separation Performance

Thin porous membranes with unidirectional oil‐transport capacity offer great opportunities for intelligent manipulation of oil fluids and development of advanced membrane technologies. However, directional oil‐transport membranes and their unique membrane properties have seldom been reported in research literature. Here, it is proven that a dual‐layer nanofibrous membrane comprising a layer of superamphiphobic nanofibers and a layer of superhydrophobic oleophilic nanofibers has an unexpected directional oil‐transport ability, but is highly superhydrophobic to liquid water. This novel fibrous membrane is prepared by a layered electrospinning technique using poly(vinylidene fluoride‐hexafluoropropylene) (PVDF‐HFP), PVDP‐HFP containing well‐dispersed FD‐POSS (fluorinated decyl polyhedral oligomeric silsesquioxanes), and FAS (fluorinated alkyl silane) as materials. The directional oil‐transport is selective only to oil fluids with a surface tension in the range of 23.8–34.0 mN m–1. By using a mixture of diesel and water, it is further proven that this dual‐layer nanofibrous membrane has a higher diesel–water separation ability than the single‐layer nanofiber membranes. This novel nanofibrous membrane and the incredible oil‐transport ability may lead to the development of intelligent membrane materials and advanced oil–water separation technologies for diverse applications in daily life and industry.

Durable superamphiphobic wood surfaces from Cu2O film modified with fluorinated alkyl silane

A simple hydrothermal process with further hydrophobization was developed for fabricating durable superamphiphobic films of cuprous oxide (Cu2O) microspheres on a wood substrate.

Facile fabrication of self-repairing superhydrophobic coatings.

A self-repairing superhydrophobic organic coating comprising polystyrene, fluorinated poly(methylsiloxane), fluorinated alkyl silane modified silica nanoparticles and photocatalytic titania nanoparticles shows self-repairing ability after mechanical damage, photocatalytic self-cleaning performance, and thus long-term outdoor durability.

Robust and Durable Superhydrophobic Cotton Fabrics for Oil/Water Separation

By introducing the incorporation of polyaniline and fluorinated alkyl silane to the cotton fabric via a facile vapor phase deposition process, the fabric surface possessed superhydrophobicity with the water contact angle of 156° and superoleophilicity with the oil contact angle of 0°. The as-prepared fabric can be applied as effective materials for the separation of water and oil mixture with separation efficiency as high as 97.8%. Compared with other materials for oil/water separation, the reported process was simple, time-saving, and repeatable for at least 30 times. Moreover, the obtained fabric kept stable superhydrophobicity and high separation efficiency under extreme environment conditions of high temperature, high humidity, strong acidic or alkaline solutions, and mechanical forces. Therefore, this reported fabric has the advantages of scalable fabrication, high separation efficiency, stable recyclability, and excellent durability, exhibiting the strong potential for industrial production.

Robust, electro-conductive, self-healing superamphiphobic fabric prepared by one-step vapour-phase polymerisation of poly(3,4-ethylenedioxythiophene) in the presence of fluorinated decyl polyhedral oligomeric silsesquioxane and fluorinated alkyl silane

A robust, electrically conductive, superamphiphobic fabric was prepared by vapour-phase polymerisation of 3,4-ethylenedioxythiophene (EDOT) on fabric in the presence of fluorinated decyl polyhedral oligomeric silsesquioxane (FD-POSS) and a fluorinated alkyl silane (FAS). The coated fabric had contact angles of 169° and 156° respectively to water and hexadecane, and a surface resistance in the range of 0.8–1.2 kΩ □−1. The incorporation of FD-POSS and FAS into the PEDOT layer showed a very small influence on the conductivity but improved the washing and abrasion stability considerably. The coated fabric can withstand at least 500 cycles of standard laundry and 10 000 cycles of abrasion without apparently changing the superamphiphobicity, while the conductivity only had a small reduction after the washing and abrasion. More interestingly, the coating had a self-healing ability to auto-repair from chemical damages to restore the liquid repellency.

Superhydrophobic nanofibre membranes: effects of particulate coating on hydrophobicity and surface properties

Superhydrophobic electrospun polyacrylonitrile nanofibre membranes have been prepared by surface coating of silica nanoparticles and fluorinated alkyl silane. The coated membranes were characterised by scanning electron microscopy, water contact angle, thermogravimetry analysis, Brunauer–Emmett–Teller, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. It was shown that the loading of nanoparticle on the nanofibre membrane was controlled by the particle concentration in the coating solution, which played a critical role in the formation of superhydrophobic surface. Increased particle loading led to higher surface roughness and WCA. The nanoparticle coating had little influence on the porosity of the nanofibre membranes. However, overloading of the particles would affect the specific surface area of the nanofibre membrane.

Fluoroalkyl Silane Modified Silicone Rubber/Nanoparticle Composite: A Super Durable, Robust Superhydrophobic Fabric Coating

A superhydrophobic fabric coating made of a crosslinked polydimethylsiloxane elastomer, containing well-dispersed hydrophobic silica nanoparticles and fluorinated alkyl silane, shows remarkable durability against repeated machine washes, severe abrasion, strong acid or base, boiling water or beverages and excellent stain resistance.

Facile Fabrication of Polysiloxane Nanorods on Magnesium Surface in the Presence of 1,6-diphosphono-hexane to Obtain a Superhydrophobic Surface

Superhydrophobic surfaces have been the focus of both industry and academic research. The high water repellency exhibited by these surfaces is based on a natural phenomenon (i.e. Lotus effect). Superhydrophobicity is explained by the Wenzel and Cassie-Baxter model. According to this model, the air trapped in micro-/nano-scale rough surfaces is a key factor in making these surfaces superhydrophobic. The trapped air and the micro-/nano-scale rough surface act to suspend the water droplet on the tops of the surface microstructure. In nature, there are many examples of plants and animals utilizing superhydrophobicity for various purposes. There are two factors that determine the superhydrophobicity of a surface. The first one is the chemical composition on the surface, which for superhydrophobicity, must have low surface energy. The second factor is the geometrical structure of the surface. Surface roughness is a key factor controlling wettability because it determines the contact area between a water droplet and the surface. One of the criteria for superhydrophobicity is that the water contact angle of the surface should be more than 150. A water droplet on even a slightly tilting superhydrophobic surface will not remain on it but will roll off. This property can be exploited to remove contaminants on a superhydrophobic surface using water droplets. The lotus leaf possesses this self-cleaning property, which originates from the wax-covered microstructures on its surface. This self-cleaning effect has been exploited for various applications such as for developing water repellency coatings, preventing snow sticking, and enhancing the lubricity of micro-fluidic devices. However, the fabrication of superhydrophobic surfaces requires the preparation of micro-/nano-scale rough surfaces, and thus many methods have been developed to fabricate such surfaces; these methods include metal atom deposition, the sol-gel method, and etching process. However, these methods are generally complex and require the use of expensive devices. Therefore, a simple and inexpensive approach for obtaining industrially feasible superhydrophobic surface is required. Polysiloxane is a well-known hybrid organic-inorganic material, and it has been studied extensively. Polysiloxane is prepared by the hydrolysis and condensation of alkyl triethoxysilanes. A series of reactions are carried out to finally produce oligomers and polymers. There are many complex reactions that produce many different polysiloxanes. Mabry et al. prepared the fluorinated polyhedral oligomeric silsesquinoxane using one-pot synthetic method. The surface that was coated with this fluorinated polyhedral compound exhibited hydrophobic property whose effectiveness was dependent on the length of the fluoroalkyl chain. Fluorinated alkyl silane and alkyl silane have been used to coat micro/nano-scale rough surfaces to obtain a superhydrophobic surface. This coating layer is transparent. Generally, the alkyl silane derivative used as the coating layer is a flexible amorphous polysiloxane or a transparent self-assembled monolayer. In 1997, Parikh et al. obtained the crystalline structure of polymerized octadesylsiloxane (PODS). Li et al. obtained a superhydrophobic surface with liquid n-octadecyl trichlorosilane. A nanosheet of PODS was obtained by coating a glass surface with liquid PODS and then dipping the glass surface in an organic solvent. The nanosheet was obtained by the forming of a self-assembled structure that then underwent polycondensation. In the present study, we have demonstrated the facile synthesis of nano-rode structures of polysiloxane on a metal surface achieved by simply dipping Mg piece in a mixture solution of alkyltriethoxysilane and 1,6-diphosphonohexane. The prepared rough surface of the Mg piece was coated with a solution of stearic acid in alcohol to obtain superhydrophobic surface.

Durable, Self‐Healing Superhydrophobic and Superoleophobic Surfaces from Fluorinated‐Decyl Polyhedral Oligomeric Silsesquioxane and Hydrolyzed Fluorinated Alkyl Silane

Aus einer homogenen Mischung polyedrischer oligomerer Silsesquioxane mit fluorierten Decylsubstituenten und hydrolysierten fluorierten Alkylsilanen wurde eine Textilbeschichtung hergestellt, die eine bemerkenswerte selbstheilende Superhydrophobie und Superoleophobie zeigt und gegen UV-Licht, Säure, wiederholte Maschinenwäsche und mechanische Beanspruchung sehr beständig ist (siehe Bild). Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Durable, Self‐Healing Superhydrophobic and Superoleophobic Surfaces from Fluorinated‐Decyl Polyhedral Oligomeric Silsesquioxane and Hydrolyzed Fluorinated Alkyl Silane

Durable, Self‐Healing Superhydrophobic and Superoleophobic Surfaces from Fluorinated‐Decyl Polyhedral Oligomeric Silsesquioxane and Hydrolyzed Fluorinated Alkyl Silane

One-step vapour-phase formation of patternable, electrically conductive, superamphiphobic coatings on fibrous materials

Patternable, electrically conductive coatings having a superhydrophobic and superoleophobic surface have been prepared by one-step vapour-phase polymerisation of polypyrrole in the presence of a fluorinated alkyl silane directly on fibrous substrates. The coated fabrics showed a surface resistance of 0.5–0.8 kΩ □−1 with water and hexadecane contact angles of 165° and 154°, respectively.

Magnet-Induced Temporary Superhydrophobic Coatings from One-Pot Synthesized Hydrophobic Magnetic Nanoparticles

In this paper, we report on the production of superhydrophobic coatings on various substrates (e.g., glass slide, silicon wafer, aluminum foil, plastic film, nanofiber mat, textile fabrics) using hydrophobic magnetic nanoparticles and a magnet-assembly technique. Fe(3)O(4) magnetic nanoparticles functionalized with a thin layer of fluoroalkyl silica on the surface were synthesized by one-step coprecipitation of Fe(2+)/Fe(3+) under an alkaline condition in the presence of a fluorinated alkyl silane. Under a magnetic field, the magnetic nanoparticles can be easily deposited on any solid substrate to form a thin superhydrophobic coating with water contact angle as high as 172 degrees , and the surface superhydrophobicity showed very little dependence on the substrate type. The particulate coating showed reasonable durability because of strong aggregation effect of nanoparticles, but the coating layer can be removed (e.g., by ultrasonication) to restore the original surface feature of the substrates. By comparison, the thin particle layer deposited under no magnetic field showed much lower hydrophobicity. The main reason for magnet-induced superhydrophobic surfaces is the formation of nano- and microstructured surface features. Such a magnet-induced temporary superhydrophobic coating may have wide applications in electronic, biomedical, and defense-related areas.