Nanofibrous Membranes Research Articles

Dual defense against membrane fouling for efficient and sustainable oil/water separation on a novel super-hydrophilic/underwater superoleophobic and catalytic nanofibrous membrane

Membrane separation technology is widely recognized as an efficient method for treating organically polluted wastewater in virtue of high performance and straightforward operation. However, the practical application of membranes is inevitably confronted with contamination issues, presenting a major challenge in terms of fouling resistance. To address this issue, a defensive-offensive dual-defense strategy based on wettability and catalytic ability control is proposed. With this concept, a novel nanofibrous membrane with a unique structure was successfully prepared through polyacrylonitrile (PAN) electrospinning, pre-oxidation, CoFe Prussian blue analogue (PBA) and polypyrrole (PPy) modification, and calcination processes. For the passive defense mode, the as-prepared membrane has shown good underwater-superoleophobicity for various types of oils, good separation capability for corresponding oil–water emulsions with retention ratios of above 99 % and fluxes ranging from 231.5 to 1524.2 L·m−2·h−1·bar−1, as well as organic solvent (dimethylformamide, DMF) resistance. For the offensive defense mode, this membrane exhibits well catalytic degradation performance for refractory pollutants with the assistance of peroxymonosulfate (PMS), which is due to the membrane being decorated with catalytic nanoparticles that contain abundant encapsulated ultra-small Fe doped Co3O4 (∼2.28 nm), and that is much smaller than the size of the pristine PBA (∼33.8 nm). Notably, the surfactants present in oil-in-water emulsions are found to be the main cause of membrane fouling, where the cationic surfactants exhibit the most significant fouling effect, while the introduction of photo-Fenton-like catalysis can endow the membrane with excellent antifouling performance and extended service life, and nearly a fully recover of emulsion separation performance was achieved. Overall, this work paves pathways to the design of advanced membranes for sustainable wastewater treatment.

An Easy Nanopatch Promotes Peripheral Nerve Repair through Wireless Ultrasound‐Electrical Stimulation in a Band‐Aid‐Like Way

AbstractLow‐intensity pulsed ultrasound (LIPUS) and electrical stimulation (ES) are effective methods that promote neural repair. However, ES usually requires electrode implantation and a power supply, which are an inconvenience to future applications. Meanwhile, it is difficult to combine ultrasound and ES through traditional methods. Herein, a nanopatch consisting of an oriented barium titanate (BTO)‐incorporated polycaprolactone (PCL) nanofiber membrane for electricity generation and a layer of graphene oxide (GO)‐doped gelatin methacryloyl (GelMA) for neural interaction is developed. This band‐aid‐like BTO@PCL/GO@GelMA nanopatch has an excellent piezoelectric performance. In vitro, the nanopatches significantly promote axonal growth under LIPUS treatment. In a rat model of erectile dysfunction caused by peripheral nerve injury, the nanopatch is easily attached to a damaged nerve similar to a band‐aid. With the assistance of ultrasound, some mechanical energy is converted into electricity by the nanopatch, and synergistic neural stimulation of ultrasound and electricity is achieved. In this way, the nanopatch significantly promoted corpus cavernosum nerve repair, resulting in the improvement of tissue structure and erectile function as well as increased conception rate in female rats. In conclusion, the nanopatch offers a synergistic ultrasound‐ES for nerve repair easily and represents a novel strategy for peripheral nerve repair.

Rationally Integrating Charge-Transfer Cocrystal and Ni(II) Organometallics for Visualized Photo/Thermochromic Sensors.

Smart materials demonstrate fascinating responses to environmental physical/chemical stimuli, including thermal, photonic, electronic, humidity, or magnetic stimuli, which have attracted intensive interest in material chemistry. However, their limited/harsh stimuli-responsive behavior or sophisticated postprocessing leads to enormous challenges for practical applications. Herein, we rationally designed and synthesized thermochromic Ni(II) organometallic [(C2H5)2NH2]2NiCl4-xBrx via a facile mechanochemical strategy, which demonstrated a reversible switch from yellow to blue color with a tunable phase-transition temperature from 75.6 to 61.7 °C. The simple electrospinning technology was applied to fabricate thermochromic Ni(II) organometallic-based nanofiber membranes for temperature monitoring. Furthermore, the organic charge-transfer cocrystal with a wide spectral absorption of 300-1950 nm and a high-efficiency photothermal conversion was combined with thermochromic Ni(II) organometallics for the desired dual-stimuli photo/thermochromism. This work supplies a new strategy for realizing multiple stimuli-responsive applications, such as thermal/light sensor displays and information storage.

Preparation of catalytic ceramic nanofiber membranes with MnFe dual-active sites enhancing catalytic ozonation of sulfamethoxazole

Membrane-based catalytic ozonation has recently attracted significant attention for its simultaneous boosted contaminant degradation and separation. In this work, catalytic ceramic nanofiber membranes ((MnFe0.05)@CNM) with MnFe dual-active site are prepared by anchoring FeOx nanoparticles onto Mn@CNM via an impregnation and in-situ precipitation method. The (MnFe0.05)@CNM coupled with catalytic ozonation was applied to the degradation of sulfamethoxazole (SMX), achieving a removal rate of up to 99.2 %. The catalytic degradation of SMX is verified by reactive oxygen species (ROS) quenching and EPR detection experiments, which shows that the 1O2, ·OH and O2·- are involved. Furthermore, (MnFe0.05)@CNM demonstrates superior catalytic stability, redox properties, and an abundance of acidic sites, as are revealed by H2-TPR and NH3-TPD analysis. The boosted performance is attributed to the synergistic catalysis by Mn and Fe bimetals under nano-confinement effect of membrane pores through facilitated electron transfer between Mn2+, Mn3+, Mn4+, Fe2+, and Fe3+, and promoting the decomposition of ozone and the generation of ROS. The nano-confinement effect of (MnFe0.05)@CNM also reduces the mass transfer distance between ROS and SMX, promoting ROS to attack the SMX molecules. This study presents a novel approach to developing catalytic ceramic membranes for the enhanced degradation of emerging contaminants in water.

Immobilization of Saccharomyces cerevisiae on polyhydroxyalkanoate/konjac glucan nanofiber membranes: Characterization, immobilization efficiency and cellular activity

Yeast immobilization systems can recoup yeast losses in continuous batch fermentation and relieve substrate or product inhibition. We report the use of solution blow spinning process to efficiently prepare polyhydroxyalkanoate (PHB) /konjac glucomannan (KGM) nanofiber membranes as immobilization carriers for Saccharomyces cerevisiae. The prepared PHB/KGM nanofiber membranes had fiber diameters similar to the scale of yeast cells. Incorporating KGM significantly enhanced the porosity (from 87.21 % to 91.74 %), crystallinity, and hydrophilicity (reducing water contact angle from 135.8° to 110.1°), while increasing the specific surface area (from 10.24 to 17.79 m2/g) of pure PHB nanofiber membranes. Thermal stability was maintained (degradation temperatures above 250 °C). These changes enhanced the force between the nanofiber membranes and the cells and facilitated their autoimmobilization on the nanofiber membranes. The highest yeast immobilization efficiency of 87.93 % could be achieved at a KGM addition ratio of 400:2. Yeast showed no loss of cellular activity on the immobilized carriers of natural materials and maintained or even improved fermentation kinetics during at least three consecutive alcoholic fermentations These findings indicate that PHB/KGM nanofiber membranes can serve as effective carriers for yeast immobilization, promoting the sustainable production of fermented foods.

Electrospun nanofibrous membranes based on fluorine-free polyimide for swift oil spill cleanup and emulsion separation

The urgent need to mitigate environmental damage caused by oil and organic pollutants in oil production industries and spill accidents necessitates effective removal methods. This study introduces novel nanofibrous membranes composed of fluorine-free polyimide, which was formed by electrospinning of BPADA-TrMPD, produced by polycondensation reaction in one-step and at high temperature using 4,4′-(4,4′-isopropylidenediphenoxy)bis-(phthalic anhydride) (BPADA) and 2,4,6-trimethyl-m-phenylenediamine (TrMPD). The resulting membranes exhibited a hydrophobic nature with a water contact angle of 114° and an oil contact angle of ∼ 0°. The adsorption performance of the nanofibers was explored using Saudi crude oil and non-polar organic solvents (i.e., n-hexane and dodecane). The developed membranes exhibited a crude oil uptake ranging from 35 to 60 g g−1 and demonstrated rapid removal capabilities, reaching equilibrium sorption capacity within a few minutes for crude oil. Moreover, these membranes displayed remarkable flux of 1991, 1508, and 206 L m−2h−1 for dodecane, n-hexane, and crude oil, respectively. The capability of the fluorine-free mats designed for oil spill cleanup was validated through its application in treating actual samples. The durability and recyclability of the membranes were showcased by regenerating them through mechanical treatment.

Nanofibrous Membranes with High Mechanical Strength for the Separation and Purification of Lysozyme

Nanofibrous Membranes with High Mechanical Strength for the Separation and Purification of Lysozyme

Electrospun poly (butylene adipate-co-terephthalate)/polydimethylsiloxane/carbon nanotubes nanofiber membranous pressure sensor for monitorable air purification and breathing detection

This research uses electrospinning to present a method for producing a pressure- and breath-responsive nanofiber membrane (PBAT/PDMS/CNTsNFM). This method utilizes polydimethylsiloxane (PDMS) and poly (butylene adipate-co-terephthalate) (PBAT), which is biodegradable, as the matrix, along with carbon nanotubes (CNTs) as a conductive filler. Additionally, a combination approach was proposed incorporating cellulose non-woven fabric (CNWF) as a support and initial filtration layer, serving as a collector for electrospinning PBAT/PDMS/CNTsNFM to create a twin-layer structure. In rheology analysis, the viscosity of PBAT/PDMS/CNTs solution was 0.811 Pa·s at the shear rate of sample preparation. PBAT/PDMS/CNTs solution performed 30.14 mN/m in the surface tension investigation. The formation mechanism of PBAT/PDMS/CNTsNFM was analyzed, and CNTs aid in forming fibers in PBAT/PDMS/CNTsNFM. PBAT/PDMS/CNTsNFM exhibits an average fiber diameter of 370 nm. In the air purification performance test (with PM0.3, 85 L/min air flow rate, 8 mg/m3 PM concentration), the 7.62 g/m2 PBAT/PDMS/CNTsNFM sample performed an air purification efficiency of 87.5 % and a pressure drop of 225 Pa, and the 22.3 g/m2 PBAT/PDMS/CNTsNFM sample performed an air purification efficiency of 92.4 % and a pressure drop of 1959 Pa. In the pressure detection test, the resistance of the 22.3 g/m2 PBAT/PDMS/CNTsNFM sample decreased as the pressure increased, and the response can be observed even at a low pressure of 25 Pa. The 7.62 g/m2 PBAT/PDMS/CNTsNFM sample could respond to breath with different strengths. The CNTs form a pressure-constructed dynamic conductive network in PBAT/PDMS/CNTsNFM. PBAT/PDMS/CNTsNFM is expected to be applied to pressure sensing, monitorable air purification, and breathing detection due to its performance in pressure detection and air purification.

Buoyancy-Assisted Fabrication of Liquid Diode: Janus Nanofibrous Membrane for Efficient Wastewater Treatment.

The pressing need for effective methods to separate oil and water in oily wastewater has spurred the development of innovative solutions. This work presents the creation and evaluation of a Janus nanofibrous membrane, also known as the Liquid Diode, developed using electrospinning (e-spinning) and buoyancy-assisted hydrothermal techniques. The membrane features a unique structure: one side is composed of PVDF nanofibers embedded with a GO/TiO2 composite, exhibiting in-air superhydrophobic and superoleophilic properties, while the reverse side consists of PVDF nanofibers with a ZnO nanorod array, demonstrating in-air superhydrophilic and underwater (UW) superoleophobic properties. This distinct asymmetric wettability enables the membrane to effectively separate both water-in-oil (w-in-o) and oil-in-water (o-in-w) emulsions, achieving an impressive liquid flux and separation efficiency (SEff). The in-air superhydrophobic side of the Janus nanofibrous membrane achieves a maximum oil flux (Fo) of 3506 ± 250 L m-2 h-1, while the in-air superhydrophilic side achieves a maximum water flux (Fw) of 1837 ± 150 L m-2 h-1, with SEff exceeding 98% for both sides. Furthermore, the Janus nanofibrous membrane maintained reliable mechanical stability after 10 cycles of sandpaper abrasion test and demonstrated excellent chemical stability when subjected to acidic, alkaline, cold water and hot water conditions for 24 h. These properties, combined with its ability in breaking down of organic contaminants (98% ± 2% in 210 min) and pharmaceutical contaminants (97% ± 2% in 210 min) under visible light, highlight its photocatalytic potential. Additionally, the membrane's antifouling and antibacterial properties suggest long-term and sustainable use in wastewater treatment applications. The synergistic combination of these superior properties positions the Janus nanofibrous membrane as a promising solution for addressing complex challenges in wastewater treatment and environmental remediation.

NBR‐Rich Nanofibrous Membranes for Hindering Composite Delamination: Comparison of the Performance Obtained Using Liquid and Photocrosslinked Rubber

AbstractThis work compares the delamination behavior of epoxy CFRPs nano‐modified with nitrile butadiene rubber/polyethylene oxide (NBR/PEO) blend nanofibrous membranes with a rubber content of 70 wt%. While the electrospun mat is able to retain the nanofibrous structure even without crosslinking, photocrosslinking is also carried to evaluate the potential different efficacy on the delamination hindering. Double cantilever beam (DCB) and end‐notched flexure (ENF) tests show significant improvements of the energy release rates (G) both in Mode I (up to ≈4 times) and Mode II (up to ≈1.5 times). In particular, the presence of “liquid” rubber (uncrosslinked mat) leads to the best reinforcing action in Mode I, while the crosslinked membrane gives the highest delamination hindering in Mode II.

Improving energy harvesting through femtosecond laser surface modification of PVDF/ZnS composite nanofibrous nanogenerators for electronic applications

Surface modification in ceramic/polymer composites holds paramount importance for electronic devices applications. Laser is a versatile and flexible device for modifying the surface characteristics of various materials. Here, we propose a novel approach to enhance the energy harvesting efficiency of polyvinylidene fluoride (PVDF) and zinc sulfide (ZnS) composite nanofibrous membranes through femtosecond laser surface modification. The electrospinning technique is used to produce nanofibers with a high β-phase content in a single step. The PVDF membrane was further enriched with ZnS nanoparticles to enhance the β-phase content. The membranes were systematically investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Electron Energy Loss spectroscopy (EELS), and Fourier-transform infrared spectroscopy (FTIR) to characterize their morphological and chemical properties. Femtosecond laser was employed to induce controlled surface modifications, resulting in hierarchical microstructures and surface functionalization. The results showed patterned tracks on the fiber surface while preserving its inherent nature. To validate its utility as an energy harvesting device, the membrane's capability was assessed by measuring the open circuit voltage. The results revealing average output voltages for nanogenerators treated with laser fluences of 0.5 J/cm2, 0.7 J/cm2, and 0.9 J/cm2 are 15.6 V, 25 V, and 17 V, respectively. The maximum output voltage is observed for a laser fluence of 0.7 J/cm2, attributed to the deeper structure created, increasing the surface area of contact and deformation in the structure. This work offers promising avenues for enhancing energy harvesting efficiency and expanding the scope of electronic devices such as sensors and actuators.

Development of sensitive biomass xylan-based carbon dots fluorescence sensor for quantification detection Cu2+ in real water and soil

Copper ions (Cu2+) pose significant risks to both human health and the environment as they tend to accumulate in soil and water. To address this issue, an innovative method using biomass-derived fluorescent carbon dots (D-CDs) synthesized via a hydrothermal process, with xylan serving as the carbon source was developed. D-CDs solution exhibited remarkable sensitivity and selectivity as a fluorescence sensor for Cu2+, boasting a low detection threshold of 0.64 μM. In order to facilitate real-time monitoring of Cu2+, solid-state fluorescent nanofiber membrane (NFD-CDs) through electrospinning was engineered. Additionally, D-CDs demonstrated successful Cu2+ detection in various real water samples, including those sourced from Xuanwu Lake, the Yangtze River, tap water, and bottled water, with accurate recovery rates observed. As a result, this research introduces a dual-mode analytical system for onsite detection of Cu2+ in real scenarios. By harnessing biomass-derived fluorescent CDs materials and solid-state fluorescence sensors, this approach offers a promising solution for addressing the challenges associated with Cu2+ contamination.

Fabrication of piezoelectric poly(l‐lactic acid) nanofiber membranes with controllable properties

AbstractPoly(l‐lactic acid) (PLLA) material has superior biocompatibility, degradability, and piezoelectricity, which have been chosen to fabricate electrospinning membranes to provide high surface area, porosity, and flexibility as applied in implantable medical devices. In this study, PLLA nanofiber membranes with adjustable performance were successfully prepared. The piezoelectricity, mechanical properties, and wettability could be tuned by the molecular weight of PLLA and the concentration of PLLA‐Dichloromethane (DCM) solution. The maximum output voltage of the PLLA nanofiber membranes could be adjusted from 0.28 to 0.55 V, and the breaking strength could vary in the range of 6.3–10.1 MPa. Furthermore, the elongation at break can be adjusted between 22% and 142%. In addition, the wettability of PLLA nanofiber membranes could be changed from hydrophobic state to hydrophilic state by surface treatment techniques. The excellent biocompatibility was further demonstrated by cell culture on hydrophilic membranes. These results implied that the molecular weight of PLLA and the concentration of PLLA‐DCM solutions could be an effective method to regulate characteristics of electrospinning membranes, which can provide more application possibilities for implantable medical devices.

D@MSNs-P/PCL antibacterial nanofibers combined with DBD cold plasma for fresh pork preservation

Fresh pork is easily contaminated by microorganisms, leading to spoilage. Dielectric barrier discharge (DBD) cold plasma technology has shown significant advantages in the preservation of meat. However, severe lipid oxidation of pork resulting from DBD treatment greatly limits its development. Herein, the antibacterial D@MSNs-P/PCL nanofiber membranes were prepared by modification polycaprolactone (PCL) with pre-reported nanomaterials (D@MSNs-P) through electrostatic spinning. Compared with the PCL membranes, the D@MSNs-P/PCL membranes showed better water stability, lower water vapor transmission rate, stronger hydrophobicity, and potent antibacterial activity. The D@MSNs-P/PCL membranes can be used for wrapping fresh pork before treatment with DBD plasma, which can not only improve the antibacterial efficiency but effectively inhibit the lipid oxidation and color change of fresh pork, extending the shelf life for 2 days. The developed D@MSNs-P/PCL membranes can also be used alone to preserve other fresh meat or oily food, with a wide range of application prospects.

Electrospun collagen/chitosan composite fibrous membranes for accelerating wound healing

The protein-polysaccharide nanofibers have attracted intensive attention in promoting wound healing, due to their components and nanoscale fibrous structure that mimics the native extracellular matrix (ECM). For the full-thickness wounds, in addition to promoting healing, hemostatic property and antibacterial activity are also of critical importance. However, currently, protein-polysaccharide-based nanofiber membranes exhibit poor mechanical properties, lack inherent hemostatic and antibacterial capabilities, as well as the ability to promote tissue repair. In this study, we developed composited membranes, which were composed of collagen (Col) and chitosan (Chs), through solvent alteration and post-processing, the membranes showed enhanced stability under physiological conditions, proper hydrophilic performance and improved mechanical property. Appropriated porosity and water vapor transmission rate, which benefit to wound healing, were detected among all the membranes except for Col membrane. Aimed at wound dressing, hemocompatibility, antibacterial activity and cell proliferation of the electrospun membranes were evaluated. The results indicated that the Col/Chs composited membranes exhibited superior blood clotting capacity, and the membranes with Chs exceeding 60% possessed sufficient antibacterial activity. Moreover, compared with Chs nanofibers, significant increase in cell grow was detected in Col/Chs (1:3) membrane. Taken together, the electrospun membrane with multiple properties favorable to wound healing, superior blood coagulation, sufficient antibacterial performance and promoting cell proliferation property make it favorable candidate for full-thickness skin wound healing.

Electrospun high hydrophilicity antimicrobial poly (lactic acid)/silk fibroin nanofiber membrane for wound dressings

Antimicrobial wound dressings can aid wound healing by preventing bacterial infection. This is particularly true of electrospun ones, which have a porous structure and can be easily loaded with antimicrobial drugs. Here, Poly lactic acid (PLA), Silk Fibroin (SF) and antimicrobial agents of Silver nanoparticles (Ag NPs) and Silver oxide (Ag2O) to prepare the PLA/SF composites antimicrobial nanofiber membrane by electrospinning. The PLA with 30 % SF nanofiber membrane show the water vapor permeability (WVP) and the liquid absorption of 36 g·mm/(m2·d·kPa) and 1721 %. With the increasing of SF contents, the degradation rate and surface hydrophilicity of the nanofiber membrane increase significantly. The nanofiber membrane exhibited excellent antimicrobial activity against Pseudomonas aeruginosa (P. aeruginosa) with the inhibition circle reach at 18.2 mm. The resultant nanofiber membrane showed high cytosolic activity, good cytocompatibility and strong antimicrobial ability, which laid a theoretical foundation for the construction of a new PLA/SF composites antimicrobial fiber membrane.

Enabling low molecular weight electrospinning through binary solutions of polymer blends

The formation of nanofibrous membranes via electrospinning is typically restricted to high molecular weight polymers in an appropriate solvent, correlated with the necessary formation of polymer chain entanglements that are needed to achieve successful production of electrospun fibers. The present work extends the electrospinning of low molecular weight polymers by investigating the electrospinning of a binary solution system consisting of two different low molecular weight polymers, using as a model system polycaprolactone (PCL) and gelatin in different ratios. The viscosities of the polymer solutions were characterized as a proxy for polymer chain entanglement and the resulting fibers were morphologically characterized by SEM imaging and further assessed water contact angle and molecular composition to determine the impact and homogeneity of the binary mixtures. We found that unitary solutions of either PCL or gelatin failed to generate proper fibers despite indications of chain entanglement. In contrast, binary solutions of low molecular weight PCL and gelatin generated different fiber quality and size distributions, depending on the ratio used, with direct correlations between fiber properties and the PCL:Gelatin ratio. It was discovered that the ratio of PCL to gelation was most predictive for successful fiber generation, with effective electrospinning occurring only for a define intermediate range of high blend ratios while both low and high blended binary solutions resulted in poor fiber production. Our study confirmed that this behavior was independent from absolute polymer concentration, indicating a unique interaction between these binary species which exists only under specific ratio concentrations and indicates promising new avenues to process low molecular weight polymers solutions.

Polystyrene Nanofibrous Membrane Infused with TiO2 Nanoparticles by a One-Step Electrospinning Process for Effective Oil–Water Separation

Polystyrene Nanofibrous Membrane Infused with TiO₂ Nanoparticles by a One-Step Electrospinning Process for Effective Oil–Water Separation

Hierarchically structured poly(lactic acid) nanofibers by organic–inorganic nanohybridization strategy towards efficient PM removal and respiratory monitoring

Despite the enormous potential in efficient removal of airborne PMs by biodegradable poly(lactic acid) (PLA) nanofiberous membranes (NFMs), current manufacturing methods still have large function gaps in providing reliable control over the fiber microstructure, membrane morphology or electret properties. Herein, the concept of organic–inorganic nanohybridization, strategically involving the combined electrospinning of PLA/TiO2 and electrospray of ZIF-8 nanodielectrics, was conceived to engender PLA NFMs (PLA/TIO@ZIF) featuring largely promoted electroactivity and surface activity, as exemplified by the increased dielectric constant and surface potential (up to 3.47 and 8.5 kV, respectively). This conferred the PLA/TIO@ZIF NFMs remarkable triboelectric nanogenerator (TENG) properties, yielding the output voltage as high as 17.9 V at 10 N and 1 Hz, and output current of 39.6 nA as driven by the humanoid respiration. Given impressive in situ electret performance and charge regeneration capability, the PLA/TIO@ZIF NFMs enabled ultrahigh PM0.3 filtering properties (90.4 %, 175 Pa, 85 L/min), accompanied by increased resistance to humidity (92.1 % removal of PM0.3, RH90 %, 32 L/min). Moreover, perfect 100 % inhibition of E. coli and S. aureus was achieved for PLA/TIO@ZIF, arising mainly from the plentiful surface charges and ROS generation. It is envisioned that the hierarchically nanostructured NFMs, offering the exceptional function integration, are highly appealing for long-term air purification and self-powered respiratory monitoring.

Antioil-Fouling Superoleophobic-Superhydrophilic Nanofibrous Membranes for Separation of Immiscible Oil–Water Mixtures and Emulsions

Antioil-Fouling Superoleophobic-Superhydrophilic Nanofibrous Membranes for Separation of Immiscible Oil–Water Mixtures and Emulsions