The wettability of graphene remains controversial owing to its high sensitivity to the surroundings, which is reflected by the wide range of reported water contact angle (WCA). Specifically, the ...surface contamination and underlying substrate would strongly alter the intrinsic wettability of graphene. Here, the intrinsic wettability of graphene is investigated by measuring WCA on suspended, superclean graphene membrane using environmental scanning electron microscope. An extremely low WCA with an average value ≈30° is observed, confirming the hydrophilic nature of pristine graphene. This high hydrophilicity originates from the charge transfer between graphene and water molecules through H–π interaction. The work provides a deep understanding of the water–graphene interaction and opens up a new way for measuring the surface properties of 2D materials.
With the assistance of environmental scanning electron microscope, the high hydrophilic nature of pristine graphene with an extremely low water contact angle of ≈30° is confirmed, using the suspended, superclean graphene membrane to exclude the interference by substrates and contamination. This high hydrophilicity is revealed to originate from the charge transfer between graphene and water molecules through H–π interaction.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
CO
geo-sequestration is a promising technology to permanently store CO
in geological formations to control the atmospheric carbon footprint. In addition, CO
is frequently utilized in enhanced oil ...recovery operations to accelerate oil production. Both, CO
geo-storage and EOR, are significantly influenced by the wettability of the associated rock/CO
/brine systems. Wettability drives the multiphase flow dynamics, and microscopic fluid distribution in the reservoir. Furthermore, while wettability is known to be influenced by varying in-situ conditions and surface chemistry of the rock/mineral, the current state-of-the-art indicates wider variabilities of the wetting states. This article, therefore, critically reviews the published datasets on CO
wettability of geological formations. Essentially, the rock/CO
/brine and rock/crude-oil/CO
-enriched-brine contact angle datasets for the important reservoir rocks (i.e. sandstone and carbonate rocks), as well as for the key minerals quartz and calcite are considered. Also, the parameters that influence wettability are critically analyzed, and the associated parametric trends are discussed and summarized. Finally, we identify pertinent research gaps and define the outlook of future research. The review, therefore, establishes a repository of the recent contact angle data, which thus assists to enhance our current understanding of the subject.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Masking tape and alkaline-assisted oxidation was used to fabricate samples.•Extreme wettability contrast improves transport capacity of wedge tracks.•Gradient wettability improves transport capacity ...of wedge tracks.•Oscillation happens at backend of wedge tracks due to excess kinetic energy.
To enhance transport capacity of open-surfaces, a gradient wettability wedge track laid on superhydrophobic background (wedge track No. 2) was fabricated by using masking tape and alkaline-assisted oxidation. The effects of gradient wettability and extreme wettability contrast are emphasized and investigated. The maximum instant velocity of a 10 μL droplet on track No. 2 is ∼ 883.53 mm/s with final transport displacement x = 46.79 mm, which was 64.15 % faster and 11.67 % farther than that on a superhydrophilic wedge track (wedge track No. 1) respectively. Oscillation happens at the wide end of wedge tracks when kinetic energy remains. Oscillation time on wedge track No. 2 is longer, which means gradient wettability can provide an extra driving force. This novel wedge track highlights the necessity of both gradient wettability and extreme wettability contrast and will have broad prospects in directional transport on open-surfaces, biological research, energy conversion and microfluidic mixers.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Achieving fast transmembrane transmission of molecules in organisms is a challenging problem. Inspired by the transport of Dopmine (DA) in organisms, the DA transporter (DAT) binds to DA in a way ...that has a ring recognition (the recognition group is the tryptophan group). Herein, D‐Tryptophan‐pillar5arene (D‐Trp‐P5) functionalized conical nanochannel is constructed to achieve fast transmission of DA. The D‐Trp‐P5 functionalized nanochannel enables specific wettability recognition of DA molecules and has great cycle stability. With the controlling of voltage to wettability, the transport flux of DA is up to 499.73 nmol cm−2 h−1 at −6 V, 16.88 times higher than that under positive voltages. In response to these results, a high‐throughput DA transport device based on controlled electricity‐wettability is provided.
The D‐Tryptophan Pillar5arene (D‐Trp‐P5) was into artificial PET conical nanochannels to construct D‐Trp‐P5 functionalized nanochannel membranes. The D‐Trp‐P5 functionalized nanochannels not only realized the wettability recognition of DA, but also realized the electricity‐wettability controlled fast transport of dopamine in the nanochannels.
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Smart surfaces with tunable wettability have aroused much attention in the past few years. However, to obtain a surface that can reversibly transit between the lotus‐leaf‐like superhydrophobic ...isotropic and rice‐leaf‐like superhydrophobic anisotropic wettings is still a challenge. This paper, by mimicking microstructures on both lotus and rice leaves, reports such a surface that is prepared by creating micro/nanostructured arrays on the shape memory polymer. On the surface, the microstructure shapes can be reversibly changed between the lotus‐leaf‐like random state and the rice‐leaf‐like 1D ordered state. Accordingly, repeated switch between the superhydrophobic isotropic and anisotropic wettings can be displayed. Research results indicate that the smart controllability is ascribed to the excellent shape memory effect of the polymer, which endows the surface with special ability in memorizing different microstructure shapes and wetting properties. Meanwhile, based on the smart wetting performances, the surface is further used as a rewritable functional platform, on which various droplet transportation programmes are designed and demonstrated. This work reports a superhydrophobic surface with switchable isotropic/anisotropic wettings, which not only provides a novel functional material but also opens a new avenue for application in controlled droplet transportation.
A novel surface that can reversibly transit between the superhydrophobic isotropic and anisotropic wetting states is reported by creating micro/nanostructured pillars on the shape memory polymer. Based on the smart controllability, the surface can be used as the rewritable functional platform, on which various droplet transportation programmes can be redesigned and displayed.
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A thermoresponsive Poly(N‐isopropylacrylamide) (PNIPAAm)‐modified nylon membrane was fabricated via hydrothermal route. Combining rough structure, proper pore size, and thermoresponsive wettability, ...the membrane can separate at least 16 types of stabilized oil‐in‐water and water‐in‐oil emulsions at different temperatures. Below the LCST (ca. 25 °C), the material exhibits hydrophilicity and underwater superoleophobicity, which can be used for the separation of various kinds of oil‐in‐water emulsions. Above the LCST (ca. 45 °C), the membrane shows the opposite property with high hydrophobicity and superoleophilicity, and it can then separate stabilized water‐in‐oil emulsions. The material exhibits excellent recyclability and high separation efficiency for various kinds of emulsions and the hydrothermal method is facile and low‐cost. The membrane shows good potential in real situations such as on‐demand oil‐spill cleanup, industrial wastewater treatment, remote operation of oil/water emulsion separation units, and fuel purification.
A temperature‐driven membrane was developed by a facile hydrothermal method. By the combination of rough structure, proper pore size, and thermoresponsive wettability, the membrane can separate both stabilized oil‐in‐water and water‐in‐oil emulsions at different temperatures. The material exhibits excellent recyclability and high separation efficiency for various kinds of emulsions.
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•Theoretical research of the jet stable stage and unsteady stage of electrospinning.•Application of functional electrospun nanofibers in biomedicine, air filtration, photocatalysis, ...and electronic battery materials.•Fabrication of modified nanofibers, special wettability nanofibers, and smart response nanofibers.•Experimental and numerical simulation studies of coalescence mechanism.
In recent years, electrospun nanofibers have gained widespread attention due to their adjustable structure, high specific surface area, and unique properties. In order to be applied in various fields such as catalysis, energy storage, medicine, filtration, and sensors, electrospun nanofibers need to have certain functionality. This review provides an overview of the theoretical research, application fields, and preparation methods of functional electrospun nanofibers. It begins by introducing the theoretical research on the jet stable stage and unsteady stage of electrospinning process. It then summarizes the applications of functional electrospun nanomaterials in biomedicine, air filtration, photocatalysis and electronic battery materials. Furthermore, it reviews the current research on modified nanofibers, special wettability nanofibers, and smart responsive nanofibers prepared using electrospinning technology. Finally, it highlights the importance of the coalescence mechanism in improving the application of electrospun coalescence materials in coalescence separation, and introduces the experimental and numerical simulation studies on this mechanism.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Wound infection and inflammation hinder the process of wound healing and bother human beings chronically. As a naturally degradable macromolecule, chitosan (CS) has been widely used in antibacterial ...wound dressings. However, the antibacterial property of chitosan is inhibited by its water insolubility. In this study, we prepared a bilayered asymmetric nanofibrous membrane with the hydrophilic CS/chitosan oligosaccharide (COS) nanofibrous membrane as the bottom layer and the hydrophobic polycaprolactone (PCL) nanofibrous membrane as the top layer. Results showed that incorporating COS improved the CS membrane's wettability, and adding 0.5 % COS increased the inhibition zone diameter of Escherichia coli and Staphylococcus aureus by 23 % and 26 %, respectively. Moreover, the PCL layer could prevent the adhesion of water and bacteria. The PCL-CS/COS0.5% membrane showed relatively good mechanical properties, excellent water absorptivity (460 %), and appropriate cytocompatibility. This asymmetric wettable membrane has a massive potential to serve as a new antibacterial dressing for wound healing.
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•Illustrate the interplay between saturation history and wettability alteration.•Erroneous prediction of oil recovery if relative permeability hysteresis is ignored.•The hysteresis ...explains oil re-trapping under different wettability conditions.•Breakthrough time changes if modified salinity influences saturation history curves.•Variable initial water saturation can be modeled only if the hysteresis is included.
Many laboratory and field scale trials have shown that modified salinity water flooding increases the mobility of oil and improves oil recovery. However, field scale simulation of the process guided by core flooding data leads to inaccurate prediction of oil recovery if the effect of the saturation history of the reservoir on relative permeability is ignored. Here, we address this problem by proposing three models illustrating the interplay among wettability alteration, hysteresis effect, and fluid flow transport in porous media. The models provide the variation of imbibition and secondary drainage saturation curves versus salinity caused by wettability alteration. Our simulations show that including hysteresis together with the wettability alteration process can better quantify the re-trapping of the oil that is mobilized due to wettability alteration of the reservoir. We further show that in the capillary transition zone, where water saturation varies from top to bottom of the reservoir, oil recovery continues for a long time, although the water cut starts early, in comparison with a reservoir with an initial uniform water saturation. Despite many experiments conducted for advanced waterflooding, our observations show that measuring the secondary drainage and imbibition saturation curves is essential and serves as a valuable input for the field scale simulation of modified salinity waterflooding of water flooded reservoirs with highly non-uniform saturation history.
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In the framework of this work, a review of the use of a barrier discharge for modifying the surfaces of various polymer products is given. There are various examples of reducing, increasing the ...wettability angle of modified samples, deforming, smoothing their surface and changing their surface energies.
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