Fluorinated Alkyl Silane Research Articles

Agricultural light-converting anti-icing superhydrophobic coating for plant growth promotion

Agricultural coatings play a crucial role in addressing the global food crisis by significantly improving the plant growth environment, accelerating plant development, and enhancing the biological quality of plants. Nevertheless, there exist constraints in the form of limited sunlight utilization, decreased light transmission caused by surface icing leading to diminished plant photosynthesis, and high cost. In this study, a cost-effective and readily scalable superhydrophobic photothermal light-conversion coating is suggested as a means to improve the light conditions necessary for optimal plant growth. By employing in situ growth of carbon dots (CDs) on the surface and interlayers of montmorillonite (MMT) and hydrolytic polymerization of fluorinated alkyl silane (FAS) on the surface of MMT, light-converting superhydrophobic materials (CDs/MMT) with a micro-nano structure were synthesized. These materials demonstrated broad-spectrum fluorescence emission suitable for utilization by plant photosynthesis. They were dispersed into an epoxy resin (ER) matrix to obtain an agricultural superhydrophobic coating (ER-CDs/MMT). The “light absorption-capture-conversion” effect confers exceptional passive anti-icing and active de-icing properties upon the coating. Furthermore, outdoor planting experiments have demonstrated its capacity to substantially enhance the light environment and enhance the biological quality of soybean and morning glory by leveraging light scattering and conversion characteristics. This underscores its considerable potential for application in the next generation of facility agriculture.

Development of a Carbon Nanotube-Enhanced FAS Bilayer Amphiphobic Coating for Biological Fluids.

This study reports the development of a novel amphiphobic coating. The coating is a bilayer arrangement, where carbon nanotubes (CNTs) form the underlayer and fluorinated alkyl-silane (FAS) forms the overlayer, resulting in the development of highly amphiphobic coatings suitable for a wide range of substrates. The effectiveness of these coatings is demonstrated through enhanced contact angles for water and artificial blood plasma fluid on glass, stainless steel, and porous PTFE. The coatings were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), atomic force microscopy (AFM), and contact angle (CA) measurements. The water contact angles achieved with the bilayer coating were 106 ± 2°, 116 ± 2°, and 141 ± 2° for glass, stainless steel, and PTFE, respectively, confirming the hydrophobic nature of the coating. Additionally, the coating displayed high repellency for blood plasma, exhibiting contact angles of 102 ± 2°, 112 ± 2°, and 134 ± 2° on coated glass, stainless steel, and PTFE surfaces, respectively. The presence of the CNT underlayer improved plasma contact angles by 29%, 21.7%, and 16.5% for the respective surfaces. The presence of the CNT layer improved surface roughness significantly, and the average roughness of the bilayer coating on glass, stainless steel, and PTFE was measured to be 488 nm, 301 nm, and 274 nm, respectively. Mechanistically, the CNT underlayer contributed to the surface roughness, while the FAS layer provided high amphiphobicity. The maximum effect was observed on modified glass, followed by stainless steel and PTFE surfaces. These findings highlight the promising potential of this coating method across diverse applications, particularly in the biomedical industry, where it can help mitigate complications associated with device-fluid interactions.

High-performance hazardous aerogel/liquid barriers from fluffy, antibacterial superhydrophobic nanofiber membranes

Fibrous membranes have been regarded as one of the most effective barriers against hazardous matters, e.g., pathogen, airborne particulates, and liquids. However, developing multi-functional membranes with high air filtration performances, liquid barrier properties, and antibacterial activities remains challenging. Herein, a robust nanofibrous membrane with fluffy structure has been developed through a facile one-step electrospinning process. Under the synergistic effect of polyetherimide (PEI) nanofibers, low surface energy fluorinated alkyl silane (FAS), and fluorinated ZIF67 nanoparticles, the resultant PEI/FAS/F-ZIF67 composite nanofiber membrane shows superhydrophobicity with WCA of 155° and antibacterial activity with efficiency of over 99 %. The addition of FAS renders the membrane a fluffy fibrous structure, which further enhances the filtration performances with a filtration efficiency of 99.99 % and a low pressure drop of 125 Pa. Owing to the superhydrophobicity, the membrane also shows excellent liquid repellent properties with hydrostatic pressures of 60.6 kPa and 14.0 kPa to water and blood, respectively. Furthermore, benefiting from the excellent thermal stability of PEI, the composite membrane can well maintain its filtration performances at high temperature of 200 ℃. Overall, the proposed PEI/FAS/F-ZIF67 nanofiber membrane demonstrates high potential to be widely applied for air purification and medical protection applications.

A new type of lipophilic hydrophobic self‐repairing cellulose insulating paper developed with ST‐110/FAS/PTFE ternary system as coating substrate

AbstractThe moisture generated by the ageing of the oil‐paper insulating system can easily lead to the deterioration of the performance of the insulating paper. In order to alleviate the impact of moisture on the performance of the insulating paper, we developed a kind of lipophilic hydrophobic self‐repairing cellulose insulating paper (new insulating paper) based on the ternary system of polytetrafluoroethylene, fluorocarbon surfactant and fluorinated alkyl silane, and accelerated thermal ageing test for 45 days at 130°C was carried out. The experimental results show that the new insulating paper with excellent lipophilic property can realise hydrophobic self‐repairing through heat treatment after physical damage. The tensile strength and elongation at break of the new insulating paper increased by 5%–8% and 6.25%–27% respectively compared with the original cellulose insulating paper. At the end of ageing, the relative dielectric constant and dielectric loss factor of new insulating paper are 10.4% and 9.9% lower than that of the original cellulose insulating paper, while the breakdown voltage is 6.8% higher. The acid and moisture content produced during the ageing process of the insulating oil impregnated with new insulating paper are also less, indicating that the coating can delay the ageing of the insulating paper.

Chemically bonded phosphate ceramic coatings with self-healing capability for corrosion resistance

Chemically bonded phosphate ceramic coatings (FCBPC) modified with organic-inorganic hybrid nano alumina (FAS-Al2O3) were prepared. The effects of FAS-Al2O3 on the morphology, corrosion resistance and self-healing properties of FCBPC are investigated. The results show that FAS-Al2O3 can improve the penetration resistance, bond strength and corrosion resistance of the coating. When the content of FAS-Al2O3 is 1.5 wt%, the impedance value at low frequency (0.01 Hz) of FCBPC3 can reach 1.52 × 106 Ω·cm2. This is mainly attributed to the introduction of organic perfluorinated long chains with low surface energy by fluorinated alkyl silane, which allows nanoparticles to be uniformly dispersed on micron alumina ceramic aggregates to build special micro-nano structures. FAS-Al2O3 can combine with AlPO4 and act as a binder to fill the pores between ceramic aggregates, increasing the cohesion of the coating and the bond strength between the coating and the substrate to the point of blocking or extending the diffusion path of corrosive media inside the coating, which in turn improves the corrosion resistance of coatings. In particular, the coatings exhibit excellent self-healing properties in terms of corrosion resistance after heat treatment. Heat treatment will cause the organic perfluorinated molecules in FAS-Al2O3 to rotate and migrate, and more fluorinated alkyl chains will be exposed, thereby minimizing the surface energy of the coating. In addition, special micro-nano structures are reconfigured due to thermally driven self-migration of organic perfluorinated chains. As a result, the hydrophobicity and impermeability of the coating are restored after heat exposure, reducing the intrusion of corrosive media, and thus the corrosion resistance of the coating has self-healing capability. This work could open up a thought-provoking idea for improving the long-term corrosion protection of phosphate ceramic coatings in high-temperature marine environments.

Near-Infrared Light Responsive Surface with Switchable Wettability in Microstructure and Surface Chemistry

Intelligent surfaces with reversibly switchable wettability have recently drawn considerable attention. One typical strategy to obtain such a surface is to change the surface chemistry or the microstructure. Herein, we report a new smart surface for which the wettability was controlled by both the surface chemistry and microstructure. Various wetting states were reversibly and precisely controlled through heating, pressing, NIR irradiation, and oxygen plasma treatment. The excellent shape memory characteristics of shape memory polyurethane (SMPU) and the controlled release of hydrophobic/hydrophilic oxygen-containing functional groups contributed to this ability. Microcapsules were used to design these smart surfaces. They controlled the release of a fluorinated alkyl silane (FAS) through shell melting, changed the surface composition, and played a decisive role in protecting the FAS against hydrolysis and evaporation to ensure that the surface's wettability is recyclable. Controlling of the surface chemistry or microstructure was repeated for at least 19 or 16 cycles, respectively, which indicated excellent repeatability compared to other smart surfaces. Based on the excellent controllability, the surface exhibited multiple functions, such as liquid directional transport and coefficient of friction control. In addition, it maintained this extraordinary ability under harsh environments owing to the great stability of the SMPU and adequate protection of the FAS by the microcapsules. With switchable wettability based on the surface chemistry and microstructure, this work provides a new principle for designing smart surfaces with wettability controlled in two ways.

Self‐healing corrosion‐resistant coatings based on fluorinated alkyl silane microcapsules

AbstractIn this study, microcapsules are prepared by in situ polymerization using the repairing agent fluorinated alkyl silane (FAS) as the core material and urea‐formaldehyde as the covering shell. Self‐healing coatings (FEP coatings) with repairing ability in water are prepared by adding FAS microcapsules in an epoxy resin matrix. The morphology, composition, and thermal properties of the microcapsules are studied. In addition, electrochemical impedance spectroscopy is used to study the barrier properties and self‐healing properties of the coating. The results show that FEP coating has good self‐healing ability, with the semiquantitative index of 105 Ω·cm2, which is greater than that of pure epoxy coating (EP coating). This is because that FAS leaked from the microcapsules reacts with water molecules to form a dense water‐insoluble film, which blocks the contact of corrosive ions with the substrate and inhibits the progress of metal corrosion. Moreover, the scratch width and depth results of the FEP coating after self‐healing also confirm the formation of the new film by FAS.

Controllable Fabrication of Durable, Underliquid Superlyophobic Surfaces Based on the Lyophilic-Lyophobic Balance.

Surfaces possessing desirable underliquid special wettability, particularly underliquid dual superlyophobicity, have a high potential for extensive applications. However, there is still a lack of controllable preparation strategies to regulate the underliquid wettability via balancing the underliquid lyophilicity-lyophobicity. Herein, we develop a nanocomposite coating system comprising silica nanoparticles (NPs), glycerol propoxylate triglycidyl ether (GPTE), and fluorinated alkyl silane (FAS) to obtain controllable underliquid special wettability surfaces. FAS is the vital factor in guiding the preparation of the surface coating with expected underliquid superwettability. Increasing the FAS content results in a tendency toward underwater superoleophobicity/underoil hydrophilicity to underwater oleophilicity/underoil superhydrophobicity. Significantly, the underliquid dual superlyophobic surface can be achieved when an appropriate FAS content is located. After the coating treatment, the fabric exhibits superamphiphilicity in air and superlyophobicity in liquid (i.e., exhibiting both underwater superoleophobicity and underoil superhydrophobicity). The coating also exhibits an adaptable antioil fouling ability and high durability against harsh environments. Furthermore, oil/water separation based on the underliquid dual superlyophobicity of coated fabrics is successfully demonstrated. Our work proposes a new fabrication principle for the design of underliquid special wettability surfaces and offers broad applications, such as switchable oil/water separation, antibiofouling, liquid manipulation, and smart textiles.

Near infrared light responsive surface with self-healing superhydrophobicity in surface chemistry and microstructure

Self-healing superhydrophobic surfaces have attracted considerable attention for enhancing the durability of superhydrophobic coatings, which have applications in various fields. However, it is difficult to find safe and effective strategies for self-healing superhydrophobic coatings to recover both microstructure and surface chemistry simultaneously. Herein, we demonstrate a high-efficiency self-healing hydrophobic surface with remote control ability. Through near infrared light (NIR) irradiation, the collapsed surface microstructure and altered surface chemistry can be recovered easily and simultaneously in a very short period. The extraordinary performance is fully discussed and can be attributed to the excellent photothermal properties of candle soot (CS). In addition, the surface demonstrates repeatable self-healing ability thanks to the good shape memory of the epoxy-based shape memory polymer (SMP) and the continued release of fluorinated alkyl silane encapsulated in microcapsules. The presented surface shows great potential and broad impacts owing to its simplicity and efficiency.

Preparation of self‐healing hydrophobic coating and its anticorrosion property

AbstractIn this study, a composite coating of polytetrafluoroethylene (PTFE) and fluorinated alkyl silane (FAS, C16H19F17O3Si) is prepared on AISI 304 L stainless steel. Scanning electron microscope and X‐ray photoelectron spectroscopy are used to analyze the microstructure and chemical group changes of PTFE–FAS coating (PF coating) before and after sulfuric acid (H2SO4) corrosion and after heat treatment. In addition, differential scanning calorimeter is performed to study the thermodynamic properties of PF coating. The corrosion resistance of PF coating under the above conditions is tested by the electrochemical experiment. The results show that acid and abrasion treatments can reduce the hydrophobic properties of the coatings, and the damage caused by acid is more serious. Heat treatment can repair the hydrophobic properties of the coating damaged by acid and abrasion. In addition, PF coating has an excellent corrosion resistance, but after H2SO4 treatment, the protection efficiency (PE) decreases from 89.09% to 2.51%, indicating that the corrosion resistance of PF is severely damaged. However, PE of PF coating increases to 76.83% after heat treatment. This repair ability improves the corrosion resistance of the coating. At the same time, the related mechanism is also clarified.

Hydrophobic coatings prepared using various dipodal silane-functionalized polymer precursors

This study introduces synthetic methodology to develop hydrophobic surfaces. Hydrophobic surfaces are fabricated via cross-linking of inorganic-organic hybrids, prepared from dipodal alkoxysilane-functionalized urethane precursors (AFUS). The inorganic-organic (I-O) hybrids are synthesized by co-hydrolysis and co-condensation of various precursors. The hybrid solutions are then used to fabricate hydrophobic coatings through spin coating method. The coatings exhibited water contact angle greater than 90°. The properties of the hydrophobic coatings are analysed and characterized using scanning electron microscopy (SEM) and contact angle measurement (CA). The precursors are characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric-differential thermal analysis (TG-DTA) and gel permeation chromatography (GPC). These environment-friendly inorganic-organic hybrid coatings have shown great potential in replacing the toxic fluorinated alkylsilane based coatings.

Super-robust self-healing superhydrophobic coating with triboelectrification induced liquid self-repellency

Superhydrophobic surfaces integrated with liquid self-repelling property have great application potential, nevertheless, it remains a major challenge for simultaneously achieving super-robust feature and extreme superhydrophobicity. In this work, a super-robust self-healing superhydrophobic coating containing cyclic olefin copolymer (COC), fluorinated alkyl silane (FAS) and polytetrafluoroethylene (PTFE) nanoparticles, is prepared by a convenient one-step wet-chemical coating method. The treated fabric has water contact angle of 168˚and sliding angle of 3˚. The coating demonstrates excellent endurance to various severe damages, e.g., repeated washing, abrasion, boiling water, strong UV irradiation, extremely high and low temperature. It also shows self-healing capability from physical/chemcial damages. Benefitting from the triboelectric negative features of COC and PTFE, this coating shows triboelectrification induced water self-repellence after rubbing with a polyamide (Nylon) fabric, water droplets can jump/move off the tribo-charged area. Moreover, this self-repelling feature works with many different aqueous liquids, such as NaCl, strong acid and alkali. Such a robust superhydrophobic coating can be applied onto many other substrates, such as cotton fabric, glass and cotton, and the treated substrates also exhibited liquid self-repellent properties after rubbing with a Nylon fabric. This triboelectrification enhanced superhydrophobic coating might shed light on developing energy-efficient liquid self-removing surfaces for various applications.

Superhydrophobic and oleophobic dual-function coating with durablity and self-healing property based on a waterborne solution

A superhydrophobic surface is typically constructed by combination of both low surface energy substance and high roughness microstructure. Although these surfaces have been widely used in the application of self-cleaning, water harvesting and anti-icing, the problems of organic solvents during the preparation process and the undesirable durability have largely limited their practical application. This paper describes a new concept and derived environmental friendly method based on a waterborne solution for the fabrication of durable superhydrophobic and oleophobic surfaces with self-healing property. In this concept, aluminum oxide particles were employed to construct the rough microstructure, fluorosurfactant and fluorinated alkyl silane were employed as low surface energy materials. The obtained surfaces coated on different substrates (glass, wood, fabric, polymer, metal) showed not only excellent water repellent performance with water contact angle larger than 150° and sliding angle is less than 10° but also oleophobic for some low surface energy organic liquid such as glycol, oleic acid, cooling oil and dimethyl formamide. The surfaces show excellent durability to solutions with different pH, abrasion resistance and self-healing by heating the oxygen-plasma-destroyed surface. The proposed coatings with excellent superhydrophobic and oleophobic performance will demonstrate the potential application in self-cleaning and antifouling.

Paper-based potentiometric sensing devices modified with chemically reduced graphene oxide (CRGO) for trace level determination of pholcodine (opiate derivative drug).

Robust, reliable and cost-effective paper-based analytical device for potentiometric pholcodine (opiate derivative drug) ion sensing has been prepared and characterized. A printed pholcodinium (PHL)2+/5-nitrobarbiturate (NB)− ion-association complex as a sensory material-based all-solid-state ion-selective electrode (ISE) on a chemically reduced graphene oxide (CRGO) solid-contact, and a printed all-solid-state Ag/AgCl reference electrode, has been combined on a hydrophobic paper substrate coated with fluorinated alkyl silane (CF3(CF2)7CH2CH2SiCl3, CF10). The sensors revealed a potentiometric slope of 28.7 ± 0.3 mV dec−1 (R2 = 0.9998) over a linear range starting from 2.0 × 10−7 M to 1.0 × 10−2 M and a detection limit of 0.04 μg mL−1. The repeatability and stability of the pholcodine paper-based sensor was found to be 2.32%. The RSD% (n = 6) was found to be 2.67% when using five different paper-based sensors. The sensor revealed an excellent selectivity towards PHL over dextromethorphan, codeine, ephedrine, carbinoxamine, caffeine, ketamine, and K+, Na+ and Ca2+ ions. It showed a good recovery (94–104%) for the determination of PHL in different artificial serum samples. The presented paper-based analytical device was successfully introduced for PHL determination in different pharmaceutical formulations (i.e. syrups and suspensions) containing pholcodine. The current work can be considered as a promising possible analytical tool to obtain cost-effective and disposable paper-based potentiometric sensing devices. These devices can be potentially manufacturable at large scales in pharmaceutical, clinical and forensic applications for opiate drug assessment.

Superamphiphobic and flame-retardant coatings with highly chemical and mechanical robustness

• A multifunctional superamphiphobic and flame-retardant coating is prepared. • Overhanging re-entrant structures are constructed by a simple spaying approach. • The surface has high mechanical/chemical resistance. • The coating offers self-extinguishing property to flammable substrates. Developing superamphiphobic coatings/surfaces with integrated flame-retardancy, mechanical robustness and corrosion resistance is significant for applications in ordinary life, chemical engineering, radionuclide separation and sewage treatment but still remains challenging, due to difficulty of simultaneously demonstrating these features. Here, a multi-functional coating, consisting of functionalized silica nanoparticles, micro-sized ammonium polyphosphate particles and fluorinated alkyl silane, is constructed. By virtue of a simple and cost-effective spaying approach, a unique randomly overhanging re-entrant and hierarchical structure can be constructed on a wide range of substrates, showing super-repellency to water and oils with low surface tensions. The created superamphiphobic surface demonstrates extremely high stability under exposure to strong corrosive chemicals (namely aqua regia, concentrated sulfuric acid and sodium hydroxide), cyclic mechanical abrasions, UV irradiation, and heat treatment. More importantly, such coating offers high flame retardancy and self-extinguishing property to flammable substrates, and the superamphiphobicity is retained even after burning. Featuring with easy processability, multi-functions and high endurance, the coating is promising for applications with multi-tasks and fire-safety requirements.

Anti-inflammatory Cotton Fabrics and Silica Nanoparticles with Potential Topical Medical Applications

The preparation of functional cotton fabrics and silica nanoparticles by direct covalent linking of nonsteroidal anti-inflammatory drugs (salicylic acid, ibuprofen, and diclofenac) through an amide group is reported. Moreover, the coating of cotton fabrics with silica nanoparticles functionalized with such antiinflamatory agents is found to increase the roughness of the surface, providing hydrophobicity to the modified fabrics. This property is enhanced by the addition of fluorinated alkyl silane in the co-condensation process to form the coating solution. Characterization of the functionalized nanoparticles and cotton textiles is accomplished by microscopic and spectroscopic techniques. The treatment of functionalized nanoparticles and cotton fabrics with model proteases and leukocytes from animal origin results in the in situ release of the drug by the selective enzymatic cleavage of the amide bond. Topical cutaneous applications in wound dressings and cream formulations for the acceleration of wound healing are envisaged.

Adsorption and Absorption of Collagen Peptides to Polydimethlysiloxane and Its Influence on Platelet Adhesion Flow Assays.

Collagen peptides are an alternative to animal derived collagens for platelet function studies under flow. The purpose of this study was to examine the use of collagen peptides in polydimethylsiloxane (PDMS) devices. Three collagen peptides with amino acid sequences and structures that capture von Willebrand factor and bind it with the platelet receptors integrin α2β1 and glycoprotein VI were patterned on glass, silicon, and PDMS. Each of these surfaces was also functionalized with tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS). Surfaces were characterized by their ability to support platelet adhesion, topology by atomic force microscopy, contact angle, and peptides absorption. PDMS readily absorbs collagen peptides, depleting them from solution, thus reducing their adsorption to glass and silicon substrates when used for micropatterning. Treatment of PDMS with FOTS, but not bovine serum albumin or poloxamer 407, inhibits collagen peptide absorption and supports adsorption and platelet adhesion at venous and arterial shear rates. Similarly, FOTS treatment of glass or silicon supports collagen peptide adsorption even in the presence of untreated PDMS. In conclusion, PDMS acts as an absorptive sink for collagen peptides, rendering a non-adhesive surface for platelet adhesion and competing for peptides when used for micropatterning. The absorption of collagen peptides can be overcome by functionalization of PDMS with a fluorinated alkyl silane, thus allowing its use as a material for micropatterning or as a surface for platelet adhesion flow assays.

Fabrication of Multifunctional Polyester Fabrics by Using Fluorinated Polymer Coatings

Facile and effective polymer coatings are highly desirable in the creation of functional surfaces for various applications. A polymer coating by using poly(vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) and a fluorinated alkyl silane (FAS-17) in volatile solvent has been proposed in the literature for the fabrication of chemically stable and superamphiphobic fabrics. This method, however, suffered from the fact that the results were unable to be experimentally reproduced by the authors. In this work, FAS-17-modified PVDF-HFP with surface energy of 14.04 mN/m was prepared through two-step reactions in acetone using coupling agent 3-aminopropyltrimethoxysilane (H2N-(CH2)3-Si-(OCH3)3) and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17, F3C-(CF2)7-(CH2)2-Si-(OC2H5)3) in the first and second reaction steps, respectively. This coating solution was then applied onto the twill weave polyester fabric using a dip-coating method. The as-fabricated surfaces exhibited extreme liquid repellency as signified by high static contact angles (149.5 °−105.7 °) against six pure liquids (water, ethylene glycol, hexadecane, pentadecane, nonane, octane) with surface tension values ranging from 72.8 to 21.4 mN/m. Furthermore, this coating showed chemical stability to strong acid (96 % sulfuric acid) and strong base (38 % sodium hydroxide). In addition to self-cleaning property, the coating also exhibited self-healing property as revealed by the static contact angle change with the plasma-and-heat treatment cycles. Moreover, it is interesting to note that coating of fabrics with the pristine solution of PVDF-HFP and FAS-17 may instead find its potential applications in oil-water separation. High separation efficiency, stability, and reusability were exhibited by the as-fabricated separation membrane.

A multichannel electrochemical all-solid-state wearable potentiometric sensor for real-time sweat ion monitoring

There is considerable interest in wearable potentiometric ion sensors that can provide information about the quality of a person's health by monitoring ion concentration levels in biofluids. Significant progress has been achieved, particularly in device integration. However, the crucial interfacial water layer and the use of transducer materials remain challenging. Herein we report a paper-based, flexible, all-solid-state, ion-selective electrode (ISE) for the real-time analysis of sweat. The super-hydrophobic paper matrix was modified with a fluorinated alkyl silane to reduce the water-layer effect. We used a high-quality graphene suspension with high conductivity and capacitance as an ion-to-electron transducer, which further stabilized the potential. The integrated solid ISE has four channels that can detect K+, Na+, Cl− and pH simultaneously. This wearable potentiometric sensor has reliable accuracy, good potential stability and low detection limits, and could be used in healthcare and clinical analysis.

Facile fabrication of omniphobic PVDF composite membrane via a waterborne coating for anti-wetting and anti-fouling membrane distillation

Omniphobic membranes have been brought to great attention recently regarding the ability to resist both water and low surface tension liquids, thus can be utilized for desalination of saline wastewater containing low surface tension contaminants in membrane distillation (MD). In this study, a facile, environment-friendly, and one-step strategy is developed for fabricating an omniphobic membrane with re-entrant structure and low surface energy by spraying a waterborne coating solution comprising of fluorocarbon surfactant (FS, Zonyl@8867L), fluorinated alkyl silane (FAS), and silicon dioxide nano-particles (SiO2 NPs) onto amino functionalized polyvinylidene difluoride (PVDF) membrane via electrostatic adsorption. As a result, the prepared omniphobic FS/FAS/Si membrane possesses high liquid repellency to water, diiodomethane, mineral oil-in-water emulsion (0.10 % v/v), mineral oil, and SDS solution (0.40 mM) with the contact angle of 164.40 ± 0.95°, 159.12 ± 3.12°, 154.31 ± 3.71°, 153.31 ± 2.09°, and 157.14 ± 3.29°, respectively. Compared to the original PVDF membrane, the omniphobic FS/FAS/Si membrane displays higher rejection (about 99.99%) and superior anti-wetting and anti-fouling characteristics even to the saline feed solution with surfactants, oil pollutants, or hydrophilic organic pollutants in MD process. The results mentioned above verify that the obtained omniphobic FS/FAS/Si membrane has potential application for the desalination of the high saline wastewater containing low surface tension contaminants.