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Surface tension and interfacial tension are crucial to the study of nanomaterials. Herein, we report a solubility method using magnesium oxide nanoparticles of different radii (1.8–105.0 nm, MgO NPs) dissolved in pure water as a targeted model; the surface tension and interfacial tension (and their temperature coefficients) were determined by measuring electrical conductivity and combined with the principle of the electrochemical equilibrium method, and the problem of particle size dependence is discussed. Encouragingly, this method can also be used to determine the ionic (atomic or molecular) radius and Tolman length of nanomaterials. This research results disclose that surface/interfacial tension and their temperature coefficients have a significant relationship with particle size. Surface/interfacial tension decreases rapidly with a radius <10 nm (while the temperature coefficients are opposite), while for a radius >10 nm, the effect is minimal. Especially, it is proven that the value of Tolman length is positive, the effect of particle size on Tolman length is consistent with the surface/interfacial tension, and the Tolman length of the bulk does not change much in the temperature range. This work initiates a new era for reliable determination of surface/interfacial tension, their temperature coefficients, ionic radius, and Tolman length of nanomaterials and provides an important theoretical basis for the development and application of various nanomaterials. [ABSTRACT FROM AUTHOR]

By employing brute-force molecular dynamics, umbrella sampling, and seeding simulations, we investigate homogeneous nucleation during melting and freezing of hard spheres. We provide insights into these opposing phase transitions from the standpoint of classical nucleation theory. We observe that melting has both a lower driving force and a lower interfacial tension than freezing. The lower driving force arises from the vicinity of a spinodal instability in the solid and from a strain energy. The lower interfacial tension implies that the Tolman lengths associated with melting and freezing have opposite signs, a phenomenon that we interpret with Turnbull's rule. Despite these asymmetries, the nucleation rates for freezing and melting are found to be comparable. [ABSTRACT FROM AUTHOR]

Polymeric surfactants are amphiphilic molecules with two or more different types of monomers. If one type of monomer interacts favorably with a liquid, and another type of monomer interacts favorably with another, immiscible liquid, then polymeric surfactants adsorb at the interface between the two liquids and reduce the interfacial tension. The effects of polymer architecture on the structural and thermodynamic properties of the liquid–liquid interface are studied using molecular simulations. The interface is modeled with a non-additive binary Lennard-Jones fluid in the two-phase region of the phase diagram. Block and gradient copolymer surfactants are represented with coarse-grained, bead-spring models, where each component of the polymer favors one or the other liquid. Gradient copolymers have a greater concentration at the interface than do block copolymers because the gradient copolymers adopt conformations partially aligned with the interface. The interfacial tension is determined as a function of the surface excess of polymeric surfactant. Gradient copolymers are more potent surfactants than block copolymers because the gradient copolymers cross the dividing surface multiple times, effectively acting as multiple individual surfactants. For a given surface excess, the interfacial tension decreases monotonically when changing from a block to a gradient architecture. The coarse-grained simulations are complemented by all-atom simulations of acrylic-acid/styrene copolymers at the chloroform-water interface, which have been studied in experiments. The agreement between the simulations (both coarse-grained and atomistic) and experiments is shown to be excellent, and the molecular-scale structures identified in the simulations help explain the variation of surfactancy with copolymer architecture. [ABSTRACT FROM AUTHOR]

Block copolymers at homopolymer interfaces are poised to play a critical role in the compatibilization of mixed plastic waste, an area of growing importance as the rate of plastic accumulation rapidly increases. Using molecular dynamics simulations of Kremer–Grest polymer chains, we have investigated how the number of blocks and block degree of polymerization in a linear multiblock copolymer impacts the interface thermodynamics of strongly segregated homopolymer blends, which is key to effective compatibilization. The second virial coefficient reveals that interface thermodynamics are more sensitive to block degree of polymerization than to the number of blocks. Moreover, we identify a strong correlation between surface pressure (reduction of interfacial tension) and the spatial uniformity of block junctions on the interface, yielding a morphological framework for interpreting the role of compatibilizer architecture (number of blocks) and block degree of polymerization. These results imply that, especially at high interfacial loading, the choice of architecture of a linear multiblock copolymer compatibilizing surfactant does not greatly affect the modification of interfacial tension. [ABSTRACT FROM AUTHOR]

Cahn introduced the concept of wall energy to describe the interaction between two immiscible fluids and a solid wall [J. W. Cahn, J. Chem. Phys. 66, 3667–3672 (1977)]. This quintessential concept has been successfully applied to describe various wetting phenomena of a droplet in contact with a solid surface. The usually formulated wall free energy results in the so-called surface composition that is not equal to the bulk composition. This composition difference leads to a limited range of contact angles which can be achieved by the linear/high-order polynomial wall free energy. To address this issue and to improve the adaptability of the model, we symmetrically discuss the formulation of the wall free energy on the Young's contact angle via Allen–Cahn model. In our model, we modify the calculation of the fluid-solid interfacial tensions according to the Cahn's theory by considering the excess free energy contributed by the distorted composition profile induced by the surface effect. Additionally, we propose a semi-obstacle wall free energy which enforces the surface composition to be the bulk composition within the framework of bulk obstacle potential. By this way, the accuracy of the contact angle close to 0° and 180° is significantly improved in the phase-field simulations. We further reveal that the volume preservation term in the conservative Allen–Cahn model has a more significant impact on the wetting behavior on superhydrophobic surfaces than on hydrophilic surfaces, which is attributed to the curvature effect. Our findings provide alternative insights into wetting behavior on superhydrophilic and superhydrophobic surfaces. [ABSTRACT FROM AUTHOR]

The interfacial behavior of macromolecules dictates their intermolecular interactions, which can impact the processing and application of polymers for pharmaceutical and synthetic use. Using molecular dynamics simulations, we observe the evolution of a random heteropolymer in the presence of liquid–liquid interfaces. The system of interest forms single-chain nanoparticles through hydrophobic collapse in water, lacking permanent crosslinks and making their morphology mutable in new environments. Complex amphiphilic polymers are shown to be capable of stabilizing high interfacial tension water–hexane interfaces, often unfolding to maximize surface coverage. Despite drastic changes to polymer conformation, monomer presence in the water phase is generally maintained and most changes are due to increased hydrophobic solvent exposure toward the oil phase. These results are then compared to the behavior at the water–graphene interface, where the macromolecules adsorb but do not remodel. The polymer's behavior is shown to depend significantly on both its own amphiphilic character and the deformability of the interface. [ABSTRACT FROM AUTHOR]

The fluid–solid interfacial tension is of great importance to many applications including the geological storage of greenhouse gases and enhancing the recovery of geo-resources, but it is rarely studied. Extensive molecular dynamics simulations are conducted to calculate fluid–solid interfacial properties in H2O + gas (H2, N2, CH4, and CO2) + rigid solid three-phase systems at various temperatures (298–403 K), pressures (0–100 MPa), and wettabilities (hydrophilic, neutral, and hydrophobic). Our results on the H2O + solid system show that vapor–solid interfacial tension should not be ignored in cases where the fluid–solid interaction energy is strong or the contact angle is close to 90°. As the temperature rises, the magnitude of H2O's liquid–solid interfacial tension declines because the oscillation of the interfacial density/pressure profile weakens at high temperatures. However, the magnitude of H2O vapor–solid interfacial tension is enhanced with temperature due to the stronger adsorption of H2O. Moreover, the H2O–solid interfacial tension in H2O + gas (H2 or N2) + solid systems is weakly dependent on pressure, while the pressure effects on H2O–solid interfacial tensions in systems with CH4 or CO2 are significant. We show that the assumption of pressure independent H2O–solid interfacial tensions should be cautiously applied to Neumann's method for systems containing non-hydrophilic surfaces with strong gas–solid interaction. Meanwhile, the magnitude of gas–solid interfacial tension increases with pressure and gas–solid interaction. High temperatures generally decrease the magnitude of gas–solid interfacial tensions. Further, we found that the increment of contact angle due to the presence of gases follows this order: H2 < N2 < CH4 < CO2. [ABSTRACT FROM AUTHOR]

The line tension of two immiscible liquids under two-dimensional and quasi-two dimensional conditions is calculated as a function of temperature, using mesoscale numerical simulations, finding that it decays linearly. The liquid–liquid correlation length, defined as the thickness of their interface, is also predicted as the temperature is varied, and it diverges as the temperature becomes close to the critical temperature. These results are compared with recent experiments on lipid membranes and good agreement is obtained. The scaling exponents of the line tension (μ) and the spatial correlation length (ν) with temperature are extracted, finding that they fulfill the hyperscaling relationship, μ = d − 1 ν , where d is the dimension. The scaling of specific heat with temperature of the binary mixture is obtained as well. This is the first report of the successful test of the hyperscaling relation between μ and ν for d = 2 and for the non-trivial case of quasi-two dimensions. This work can help to understand experiments that test properties of nanomaterials using simple scaling laws, without needing to know specific chemical details of those materials. [ABSTRACT FROM AUTHOR]

The storage of CO2 and hydrogen within depleted gas and oil reservoirs holds immense potential for mitigating greenhouse gas emissions and advancing renewable energy initiatives. However, achieving effective storage necessitates a thorough comprehension of the dynamic interplay between interfacial tension and wettability alteration under varying conditions. This comprehensive review investigates the multifaceted influence of several critical parameters on the alterations of IFT and wettability during the injection and storage of CO2 and hydrogen. Through a meticulous analysis of pressure, temperature, treatment duration, pH levels, the presence of nanoparticles, organic acids, anionic surfactants, and rock characteristics, this review elucidates the intricate mechanisms governing the changes in IFT and wettability within reservoir environments. By synthesizing recent experimental and theoretical advancements, this review aims to provide a holistic understanding of the processes underlying IFT and wettability alteration, thereby facilitating the optimization of storage efficiency and the long-term viability of depleted reservoirs as carbon capture and storage or hydrogen storage solutions. The insights gleaned from this analysis offer invaluable guidance for researchers, engineers, and policymakers engaged in harnessing the potential of depleted reservoirs for sustainable energy solutions and environmental conservation. This synthesis of knowledge serves as a foundational resource for future research endeavors aimed at enhancing the efficacy and reliability of CO2 and hydrogen storage in depleted reservoirs. [ABSTRACT FROM AUTHOR]

The purpose of the surfactants used is to greatly reduce the interfacial tension between the crude oil and brine, thereby decreasing the capillary number. The resulting oil-in-water emulsions are often grouped according to the Winsor theory. Oil recovery aims to produce Winsor type-III emulsions because they have the lowest interfacial tension values and the most favorable flow properties. The sensitivity of oil–water–surfactant systems to environmental influences (e.g., mixing speed and equilibration time) increases close to the favorable environmental range (temperature, brine total salt concentration, pressure, etc.) of the Winsor III type, the middle microemulsion phase, which is favorable for crude oil recovery. The tests aimed to investigate the quality and quantity of emulsions prepared with surfactants used in enhanced oil recovery (EOR) using an automatic device to characterize and select surfactants for industrial petroleum applications. An essential method for surfactant selection is to study the emulsifying effect and phase behavior. Phase behavior tests and emulsifying effect tests were performed on surfactants and surfactant packages as a function of mixing parameters. The mixing speed and mixing time can influence the results of the phase behavior and emulsifying effect tests, although during the investigations, other parameters were unchanged. [ABSTRACT FROM AUTHOR]

Inclusions are one of the important factors affecting the cleanliness of molten steel. The current optimization of inclusion removal methods mainly focuses on promoting inclusions to float to the slag–steel interface so that the inclusions can be absorbed and removed by the refining slag. However, the research on the floating removal of inclusions cannot be carried out directly in the ladle, so methods such as mathematical models and physical models were developed. This article uses silicone oil to simulate the slag layer; polypropylene particles; and aluminum oxide particles to simulate inclusions to establish a water model experiment. By changing the viscosity of silicone oil and the diameter of particles, the factors affecting the movement of inclusions at the slag–steel interface were explored. Based on the water model, a mathematical model of the floating behavior of inclusions at the slag–steel interface was constructed, and parameters such as particle diameter and interfacial tension in the water model experiment were studied by the mathematical model for calculation. Both the mathematical model and the water model experimental results show that after the viscosity of silicone oil increases from 0.048 Pa·s to 0.096 Pa·s, the dimensionless displacement and terminal velocity of the particles decreases. When the diameter of the same particle increases, the dimensionless displacement and terminal velocity increases. The dimensionless displacement of polypropylene particles of the same diameter is larger than that of aluminum oxide particles, and the terminal velocity is smaller than that of aluminum oxide particles. This is attributed to the better overall three-phase wettability of polypropylene particle. When the liquid level increases, the dimensionless displacement and terminal velocity of particles under the same conditions show only slight differences (less than 10%). [ABSTRACT FROM AUTHOR]

[Display omitted] • Micelles were in situ incorporated into the thin film nanocomposite (TFN) membrane. • The stable and monodispersed micelles can essentially regulate the interfacial polymerization (IP) process. • The structure of polyamide layer was optimized by further refinement of the IP process. • The resultant TFN membrane exhibited high water permeance (20.7 L m-2h−1 bar−1) and superior Na 2 SO 4 rejection (99.3 %). The desalination performance of thin film nanocomposite (TFN) membranes is significantly influenced by the nature of nanofillers and the structure of the polyamide (PA) layer. Herein, a micelles regulated interfacial polymerization (MRIP) strategy is reported for the preparation of TFN membranes with enhanced nanofiltration (NF) performance. Specially, stable and ultrafine micelles, synthesized from the poly(ethylene oxide)- b -poly(4-vinyl pyridine)- b -polystyrene (PEO-PVP-PS) triblock copolymers, were utilized as regulators in the aqueous phase during the interfacial polymerization (IP) process. TFN membranes were fabricated with varying concentrations of micelles to improve their properties and performances. The structure of the PA layer was further regulated by modulating the content of trimesoyl chloride (TMC), which significantly enhances the performance of the TFN membrane with micelles. Attributable to the homogeneously dispersed micelles and the modified PA layer, the optimized membrane denoted as TFN-2–0.3 exhibits an improved separation performance of 20.7 L m-2h−1 bar−1 and 99.3 % Na 2 SO 4 rejection, demonstrating nearly twice the permeance and 2.7 % higher rejection than that of the original control membrane, respectively. The mechanism of this MRIP strategy was investigated through the diffusion experiments of piperazine (PIP) and interfacial tension tests. The incorporated micelles effectively lower the interfacial tension, promote the diffusion of PIP and accelerate the IP reaction, resulting in a denser and thinner PA layer. Collectively, these findings demonstrate that TFN membranes with micelles exhibit increased roughness, enhanced hydrophilicity, superior rejection to divalent salts, and better acid-base resistance, highlighting their potential applications in the design of TFN membranes. [ABSTRACT FROM AUTHOR]

[Display omitted] Pickering emulsions have attracted increasing attention from multiple fields, including food, cosmetics, healthcare, pharmaceutical, and agriculture. Their stability relies on the presence of colloidal particles instead of surfactant at the droplet interface, providing steric stabilization. Here, we demonstrate the microscopic attachment and detachment of particles with tunable contact angle at the interface underlying the Pickering emulsion stability. We vary the interfacial tension continuously by varying the temperature offset of a phase-separated binary liquid from its critical point, and employ confocal microscopy to directly observe the particles at the interface to determine their coverage and contact angle as a function of the varying interfacial tension. When the interfacial tension decreases upon approaching the binary liquid's critical point, the contact angle and detachment energy (ΔE) drop, and the particles move out of the interface. Microscopic imaging suggests necking and capillary interactions lead to clustering of the particles, before they eventually desorb from the interface. Macroscopic measurements show that concomitantly, coalescence takes place, and the emulsion loses its stability. These results reveal the interplay of interfacial energies, contact angle and surface coverage that underlies the Pickering emulsion stability, opening up ways to manipulate and design the stability through the microscopic behavior of the adsorbed particles. [ABSTRACT FROM AUTHOR]

[Display omitted] The droplet/bubble adhesion characteristics depend on the length of the droplet/bubble three-phase contact line. Since the deformation caused by the liquid–gas interfacial tension on the soft substrate, referred as to the wetting ridge, retards contact line spreading and retraction, we conjecture that the droplet/bubble adhesion characteristics depend also on the substrate softness. Soft substrates with various shear moduli are prepared and characterized by the spreading and receding dynamics of water droplets and underwater bubbles. Snap-in and normal adhesion forces of droplets/bubbles on such soft substrates are directly measured along with the visualized droplet/bubble shape profiles. The droplet/bubble snap-in force, which corresponds to the short-time spreading dynamics, decreases with a decrease in the substrate shear modulus because of the retarded contact line spreading. The droplet maximal adhesion force on a soft substrate can be counterintuitively either smaller or larger than its counterpart on the rigid substrate depending on different dwelling times, i.e., the droplet/bubble-substrate contact time before droplet/bubble-substrate separation. The former is attributed to the retarded contact line spreading, whereas the latter is attributed to the retarded contact line retraction. The substrate softness- and dwelling time-dependent droplet/bubble adhesion reported in this study will benefit various applications related to soft substrates. [ABSTRACT FROM AUTHOR]

[Display omitted] Hypothesis : Microcapsule formation, following internal phase separation by solvent evaporation, is controlled by two main factors of thermodynamic and kinetic origin. Morphology prediction has previously focused on the final thermodynamical state in terms of spreading conditions, limiting the prediction accuracy. By additionally considering kinetic effects as the emulsion droplet evolves through the two-phase region of its ternary phase diagram during solvent evaporation, this should enhance prediction accuracy and explain a wider range of morphologies. Experiments : Dynamical interfacial tensions, and thereby spreading coefficients, during the formation of poly(methyl methacrylate) and poly(d , l -lactic- co -glycolic acid) microcapsules were measured by first establishing the boundaries and tie-lines of the ternary system in the emulsion droplets. Kinetic effects during the formation were investigated by varying the solvent evaporation rate and hence the time for polymer shell formation equilibration. The theory was validated by comparing predicted morphologies to microscopic snapshots of intermediate and final morphologies. Findings : The proposed theory explained both intermediate acorn and core–shell morphologies, where a late transition from acorn to core–shell produced microcapsules containing highly off-centered cores. By considering the kinetic factors, the formulation could be altered from yielding kinetically frozen acorns to core–shell and from yielding multicore to single core microcapsules. [ABSTRACT FROM AUTHOR]

The results revealed the significant effect of NaCl, KCl, CaCl2, MgCl2, CaSO4, MgSO4, and Na2SO4 and pH values of 3.5–11 on the interfacial tension (IFT) reduction using three types of neutral, acidic, and basic crude oils, especially for acidic crude oil (crude oil II) as the pH was changed from 3.5 to 11 (due to saponification process). The findings showed the highest impact of pH on the IFT of crude oil II with a reducing trend, especially for the pH 11 when no salts exist. The results revealed that the salts except MgCl2 and CaCl2 led to a similar IFT variation trend for the case of distilled water/crude oil II. For the MgCl2 and CaCl2 solutions, a shifting point for IFT values was inevitable. Besides, the dissolution of 1-dodecyl-3-methyl imidazolium chloride ([C12mim][Cl]) with a concentration of 100–1000 ppm eliminates the effect of pH on IFT which leads to a reducing trend for all the examined crude oils with minimum IFT of 0.08 mN/m. Finally, the [C12mim][Cl] adsorption (under pH values) for crude oils using only Na2SO4 was measured and the minimum adsorption of 0.41 mg surfactant/g Rock under the light of saponification process was obtained. [ABSTRACT FROM AUTHOR]

Extensive research has demonstrated the potential of cell viscoelastic properties as intrinsic indicators of cell state, functionality, and disease. For this, several microfluidic techniques have been developed to measure cell viscoelasticity with high-throughput. However, current microchannel designs introduce complex stress distributions on cells, leading to inaccuracies in determining the stress--strain relationship and, consequently, the viscoelastic properties. Here, we introduce a novel approach using hyperbolic microchannels that enable precise measurements under a constant extensional stress and offer a straightforward stress--strain relationship, while operating at a measurement rate of up to 100 cells per second. We quantified the stresses acting in the channels using mechanical calibration particles made from polyacrylamide (PAAm) and found that the measurement buffer, a solution of methyl cellulose and phosphate buffered saline, shows strain-thickening following a power law up to 200 s-1. By measuring oil droplets with varying viscosities, we successfully detected changes in the relaxation times of the droplets and our approach could be used to get the interfacial tension and viscosity of liquid--liquid droplet systems from the same measurement. We further applied this methodology to PAAm microgel beads, demonstrating the accurate recovery of Young's moduli and the near-ideal elastic behavior of the beads. To explore the influence of altered cell viscoelasticity, we treated HL60 human leukemia cells with latrunculin B and nocodazole, resulting in clear changes in cell stiffness while relaxation times were only minimally affected. In conclusion, our approach offers a streamlined and time-efficient solution for assessing the viscoelastic properties of large cell populations and other microscale soft particles. [ABSTRACT FROM AUTHOR]

Low permeability reservoirs have starting pressure gradient in the oil-water phase seepage, fully understanding the change and influence factor of starting pressure gradient in water driving oil. In order to get a thorough understanding of starting pressure gradient’s characteristic and influence factor in oil-water phase seepage, the starting pressure gradients of different permeability, different water saturation and different wettability cores in two-phase seepage during water flooding were experimentally measured in laboratory, according to the experimental phenomenon, resistance effect and microgenesis generating starting pressure in the cores’ hole have been analysed. The result of research shows that the starting pressure gradients of cores that permeability below 50 × 10 -3 μm² are incremental with water saturation growing. The starting pressure of cores that permeability above 50 ×10 -3 μm² don’t change much with the permeability changing, and the whole trend is declining, the values of starting pressures are small. For low permeability reservoirs, the cores permeability and wettability index are smaller, the boundary layer thickness are larger, the starting pressure gradients are larger. The adding resistance effects producing starting pressure gradient have the frictional drag caused by oil drop capillary pressure, the resistance caused by oil bead deformation from static wetting lag and the resistance caused by liquid resistance effect, whose values are related to pore throat radius, wettability index, oil and water distribution in microscopic pores, boundary layer thickness and solid-liquid interfacial tension. [ABSTRACT FROM AUTHOR]

Consumers are concerned about employing green processing technologies and natural ingredients in different manufacturing sectors to achieve a "clean label" standard for products and minimize the hazardous impact of chemical ingredients on human health and the environment. In this study, we investigated the effects of gelatinized starch dispersions (GSDs) prepared from six plant sources (indica and japonica rice, wheat, corn, potatoes, and sweet potatoes) on the formulation and stability of oil-in-water (O/W) emulsions. The effect of gelatinization temperature and time conditions of 85–90 °C for 20 min on the interfacial tension of the two phases was observed. Emulsification was performed using a primary homogenization condition of 10,000 rpm for 5 min, followed by high-pressure homogenization at 100 MPa for five cycles. The effects of higher oil weight fractions (15–25% w/w) and storage stability at different temperatures for four weeks were also evaluated. The interfacial tension of all starch GSDs with soybean oil decreased compared with the interfacial tension between soybean oil and water as a control. The largest interfacial tension reduction was observed for the GSD from indica rice. Microstructural analysis indicated that the GSDs stabilized the O/W emulsion by coating oil droplets. Emulsions formulated using a GSD from indica rice were stable during four weeks of storage with a volume mean diameter (d4,3) of ~1 µm, minimal viscosity change, and a negative ζ-potential. [ABSTRACT FROM AUTHOR]

The present work explores the shear and extensional rheology of immiscible multi-micro/nanolayered systems comprising low-density polyethylene (LDPE) paired with polystyrene (PS) and polycarbonate (PC) obtained from forced-assembly multilayer coextrusion. Firstly, miscible multilayer references based on LDPE/LLDPE layers were prepared with their miscibility characterized by shear and elongational measurements. Their strain hardening behaviors were found to be intricately linked to the number of layers and confinement. Secondly, for immiscible LDPE/PS and LDPE/PC multilayers with symmetric (50/50) and asymmetric (10/90) compositions, negative deviation of complex viscosities from neat polymers was highlighted because of the heightened confinement of LDPE chains by PS or PC and reduced entanglements at polymer–polymer interfaces. Intriguingly, LDPE/PC systems exhibited no strain hardening irrespective of layer configuration, while the geometric confinement imposed by PS layers facilitated interactions between single chains with long-chain branching (LCB), leading to strain hardening under specific conditions. Furthermore, the extensional viscosities were predicted using the Macosko model (C.W. Macosko et al. Journal of Rheology. 63 2019), accurately describing the behavior of 1024 layered films for both asymmetric (10/90) LDPE/PS and LDPE/PC systems, but not for 32 layers due to a limited number of interfaces. This study provides insights into quantifying interfacial tension properties in micro/nano-layered systems with high mismatched viscoelastic polymers, shedding light on their strain hardening properties in the presence of increased interfacial area. [ABSTRACT FROM AUTHOR]

New approaches to low salinity water (LSW) injection methods, such as LSW/surfactant, LSW/polymer, and LSW/nanofluid flooding, have been studied for oil reservoirs. Numerous researchers discussed the mechanisms related to enhanced oil recovery (EOR) efficiency and highlighted the significant impact of the wettability alteration and interfacial tension (IFT) reduction. This work studied the effect of exposure time on the wettability alteration and IFT in the LSW/nanoparticle (LSWN) flooding. Contact angle tests investigated rock wettability over a series of different times. A pendant drop tensiometer was used to measure the IFT. By coreflood apparatus, waterflood tests were also conducted, considering the effect of soaking time. Laboratory results showed that the involved mechanisms are time-dependent. More water-wet conditions and higher oil recovery were obtained under longer soaking time. In addition, the positive effect of LSWN was observed in tertiary flooding tests. The results also indicate that the effect of water-soluble oil compounds should be considered in measuring wettability and IFT. [ABSTRACT FROM AUTHOR]

[Display omitted] The question of why aqueous solutions of some surfactants demonstrate a rapid spreading (superspreading) over hydrophobic solid substrates, while solutions of other similar surfactants do not, has no definitive explanation despite numerous previous studies. The suggested hypothesis for this study assumes that once the spreading coefficient of surfactant is positive, there is a concentration range for solutions of any surfactant which demonstrates rapid spreading. As it is impossible to calculate spreading coefficients for solid substrates, we compare the spreading performance of known superspreaders and non-superspreaders on liquid (oil) substrate. The kinetics of spreading of aqueous solutions of a series of branched ionic surfactants and non-ionic trisiloxane surfactants on two liquid substrates was studied and compared with the spreading of a surfactant-free liquid, silicone oil. Both dynamic and equilibrium spreading coefficients were calculated using measured surface and interfacial tensions. There is no difference in spreading rate on liquid substrate between solutions of surfactants proven as superspreaders (while spreading on solid substrate) or non-superspreaders. A rapid spreading (superspreading) with the characteristic rate of spreading O(102–103) mm2/s occurs if the dynamic spreading coefficients exceeds the positive threshold value. If the dynamic spreading coefficient is negative or slightly positive, complete wetting still occurs, but the spreading is slow with the spreading rate is O(1) mm2/s. Spreading exponents for surfactant solutions in the rapid spreading regime are considerably larger than for the surfactant-free liquid. A number of spreading and dewetting patterns were observed depending on the surfactant type, its concentration and substrate. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive analysis of interfacial tension (IFT) between pore water and hydrogen-cushion gas mixtures in subsurface porous media, a key variable in the distribution of gas mixtures for hydrogen storage. Employing molecular dynamics simulations, we developed two IFT models at 20 MPa and 373 K: one for an H 2 –CO 2 –H 2 O system and another for an H 2 –CH 4 –H 2 O system. The models reveal that increasing cushion gas concentration reduces gas-water IFT. Notably, for H 2 –CO 2 –H 2 O mixtures, the IFT substantially decreases with CO 2 concentration up to 40%, after which the reduction rate diminishes. In H 2 –CH 4 –H 2 O mixtures, the IFT decreases linearly with CH 4 concentration. The study attributes these variations to local density distributions and molecular orientation effects. Specifically, CO 2 adsorption at the interface up to 40% concentration significantly lowers IFT, while CH 4 adsorption proportionally decreases IFT. The influence of CO 2 on water molecule orientation at the interface, in contrast to the non-effect of CH 4 , is also critical in enhancing IFT reduction. Our results also highlight the reduction of H 2 self-diffusion at the interface caused by CO 2 and CH 4 , an essential factor in optimizing subsurface hydrogen storage operations. • Cushion gas concentration impacts water/H₂ and CO₂/CH₄ IFTs under subsurface storage conditions. • Increasing CH₄ reduces water-H₂-CH₄ IFT linearly, while CO₂ shows an initial sharp decrease. • CO₂ and CH₄ differently affect IFT due to their unique adsorption at the gas-water interface. • Water-H₂-CO₂ mixtures have lower IFTs than H₂-CH₄ due to CO₂'s molecular interaction at the interface. • Higher CO₂ or CH₄ concentration lowers H₂ self-diffusion at the gas-water interface. [ABSTRACT FROM AUTHOR]

Polymer flooding has achieved considerable success in medium–high permeability reservoirs. However, when it comes to low-permeability reservoirs, polymer flooding suffers from poor injectivity due to the large molecular size of the commonly used high-molecular-weight (high-MW) partially hydrolyzed polyacrylamides (HPAM). Herein, an amphiphilic polymer (LMWAP) with a low MW (3.9 × 106 g/mol) was synthesized by introducing an amphiphilic monomer (Allyl-OP-10) and a chain transfer agent into the polymerization reaction. Despite the low MW, LMWAP exhibited better thickening capability in brine than its counterparts HPAM-1800 (MW = 1.8 × 107 g/mol) and HPAM-800 (MW = 8 × 106 g/mol) due to the intermolecular hydrophobic association. LMWAP also exhibited more significant shear-thinning behavior and stronger elasticity than the two counterparts. Furthermore, LMWAP possesses favorable oil–water interfacial activity due to its amphiphilicity. The oil–water interfacial tension (IFT) could be reduced to 0.88 mN/m and oil-in-water (O/W) emulsions could be formed under the effect of LMWAP. In addition, the reversible hydrophobic association endows the molecular chains of LMWAP with dynamic association–disassociation transition ability. Therefore, despite the similar hydrodynamic sizes in brine, LMWAP exhibited favorable injectivity under low-permeability conditions, while the counterpart HPAM-1800 led to fatal plugging. Furthermore, LMWAP could enhance oil recovery up to 21.5%, while the counterpart HPAM-800 could only enhance oil recovery by up to 11.5%, which could be attributed to the favorable interfacial activity of LMWAP. [ABSTRACT FROM AUTHOR]

Surfactant-assisted spontaneous imbibition is an important mechanism in enhanced oil recovery by capillary pressure in low permeability and tight oil reservoirs. Though many experiments have been conducted to study the mechanism of enhanced oil recovery by surfactant-assisted spontaneous imbibition, the effects of surfactant type, concentration, and temperature have not been well studied. Using tight sandstone outcrop core samples with similar permeability and porosity, this paper experimentally studies surfactant-assisted spontaneous imbibition using three different surfactant types, i.e., sodium dodecylbenzene sulfonate (SDBS), cocamidopropyl betaine (CAB), and C12–14 fatty alcohol glycoside (APG). In addition to the type of surfactant, the effect of the surfactant concentration and the temperature is also investigated. The study results show that the ultimate oil recovery of spontaneous imbibition with formation water and denoised water is about 10%. Surfactant can significantly improve the oil recovery of spontaneous imbibition by reducing the interfacial tension between oil and water, emulsifying crude oil and improving oil mobility. APG showed better performance compared to SDBS and CAB, with a maximum oil recovery factor of 36.19% achieved with formation water containing 0.05% APG surfactant. Lower concentrations (0.05% APG) in the formation water resulted in a higher oil recovery factor compared to 0.1% APG. Increasing temperature also improves oil recovery by reducing oil viscosity. This empirical study contributes to a better understanding of the mechanism of surfactant-assisted spontaneous imbibition and enhanced oil recovery in tight oil reservoirs. [ABSTRACT FROM AUTHOR]

We introduce a particle levitation tensiometry to accurately quantify ultra-low interfacial tensions in liquid–liquid phase separation (LLPS) systems, crucial for understanding the structure and dynamics of membrane-less organelles in biological cells. Our technique uses non-reactive spherical microparticles to balance gravitational and interfacial forces, providing precise, repeatable, and reliable measurements across a wide range of LLPS systems, including aqueous two-phase systems, coacervates, and immiscible oil–oil systems. By adjusting the Bond number through variations in the bead size and density, our method allows for accurate interfacial tension measurements across values as low as 0.37 μN/m with minimal deviation and efficiently detects substantial variations in interfacial tensions with changes in compositions, concentrations, and ionic strengths; for instance, it recorded a change from 7.34 μN/m at a polyelectrolyte concentration of 0.002 M to 8.26 μN/m at 0.003 M. Our findings offer insights into the dynamics of LLPS and open pathways for applications in fields where accurate interfacial tension measurement is crucial, enhancing our understanding of cellular processes and enabling practical applications in drug delivery, adhesives, and coatings. [ABSTRACT FROM AUTHOR]

In situ AFM observations show that when PILP droplets contact a surface, their initial properties are either a liquid with a high interfacial tension (350 mJ m−2) or a soft gel-like material with a low modulus (less than 0.2 MPa). These findings suggest that PILP may initially be liquid-like to infiltrate collagen fibrils, enabling the production of interpenetrating composites, and/or become viscoelastic, to provide a means for moulding minerals. [ABSTRACT FROM AUTHOR]

In this study, the miscibility of ethylene vinyl acetate/olefin block copolymer (EVA/OBC) blends was investigated through the determination of melt-state viscoelastic properties as well as by morphological analysis using experimental and theoretical approaches. The SEM micrographs showed droplet-matrix morphology, and the blend containing a higher content of OBC exhibited the highest OBC-dispersed phase domain size. The complex viscosity of EVA/OBC blends showed a positive deviation from the log-additivity rule at all compositions, which indicates the strong interaction between phases. Cole–Cole and Han plots indicated miscibility in the molten state between EVA and OBC. The interfacial tension of EVA/OBC blends was determined by the implementation of Palierne and Bousmina emulsion models. Moreover, the blend samples were characterized in terms of creep properties using a dynamic mechanical analyzer, which demonstrated that the OBC increased the creep strains of the blends. The four-element Burger model and the Findley power law model were employed to model the creep behaviors of the EVA, OBC, and blend samples. The model predictions indicated that the incorporation of OBC into the EVA improved the creep rate of EVA/OBC blends significantly. [ABSTRACT FROM AUTHOR]

In this study, the effect of salinity on the enhanced oil recovery process in the presence of commercial silica nanoparticles and a new synthesized polymeric ZnO/SiO2/Xhantan nanocomposites (NCs) at reservoir conditions were investigated. First, the crystal structure and morphology of the NCs were investigated using x-ray diffraction, Scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller, and energy-dispersive x-ray. Then, the effect of silica nanoparticles and NCs on the change of wettability and interfacial tension at different salinities and reservoir conditions was studied. For 2 SW (seawater) and 10 SW (two times diluted seawater), silica and NCs decreased contact angle from (79 °, 75 °) to (78 °, 74 °) and (70 °, 62 °), respectively. Zeta potential results are −31.37 and −28.00 for 10 SW and 2 SW concentrations, which show the perfectly stable and relatively stable regions, respectively. Moreover, interfacial tension was decreased more in the presence of 10 SW in comparison to 2 SW, and the oil recovery at 2 SW and 10 SW concentrations were 51.71% and 70.25%, respectively, at 0.05 wt% NCs concentration which main reasons are improving wettability, interfacial tension, and stability. [ABSTRACT FROM AUTHOR]

Traditional methods for the enrichment of microorganisms rely on growth in a selective liquid medium or on an agar plate, followed by tedious characterization. Droplet microfluidic techniques have been recently used to cultivate microorganisms and preserve enriched bacterial taxonomic diversity. However, new methods are needed to select droplets comprising not only growing microorganisms but also those exhibiting specific properties, such as the production of value-added compounds. We describe here a droplet microfluidic screening technique for the functional selection of biosurfactant-producing microorganisms, which are of great interest in the bioremediation and biotechnology industries. Single bacterial cells are first encapsulated into picoliter droplets for clonal cultivation and then passively sorted at high throughput based on changes in interfacial tension in individual droplets. Our method expands droplet-based microbial enrichment with a novel approach that reduces the time and resources needed for the selection of surfactant-producing bacteria. [ABSTRACT FROM AUTHOR]

Despite their hazardous nature, carbonaceous particles (CPs) own very appealing properties, which make them a leading material in numerous applications. A systematic work on the properties of aqueous dispersions containing CPs, cetylpyridinium chloride (CPyCl), and sodium salicylate (NaSal) is here presented. Being CPs not soluble in water, an effective preparation method to obtain stable and homogeneous solutions was developed. Furthermore, a full characterization of the systems was performed by means of UV-Visible absorption spectroscopy, rheology, and interfacial tension measurements. Hydrophobic CPs are hard to disperse in a water matrix. The adoption of CPyCl as solubility enhancer was a sound strategy to finely disperse high concentration of CPs in an aqueous environment. The high CPs concentration involved conferred to the solutions a dark color and peculiar properties, such as UV and visible light radiation absorbance. The addition of NaSal to the CPyCl-CPs water solutions donated to the system robust viscoelasticity. We investigated 100 mM CPyCl aqueous solutions, with 60 and 70 mM NaSal, containing various amounts of CPs (0–9500 ppm). CPs at concentrations beneath 9500 ppm do not influence the system rheological properties. The well-known effect of NaSal on CPyCl solutions remains unaltered even in the presence of CPs at concentrations below 9500 ppm. On the other hand, the addition of 9500 ppm CPs provokes a moderate change in the rheological properties and microstructure of the systems. At a such high concentration, CPs seem to mimic the effect of NaSal on the micellar solutions, acting as a full-fledged hydrophobic salt. [ABSTRACT FROM AUTHOR]

The targeted delivery of a hydrophilic Tripeptide-3 to the skin using microemulsions or nanoemulsions for facial oil reduction was the focus of this study. The impact factors affecting oil/water transparent dispersion formation, such as the surfactant system, HLB value, and co-solvent, were identified through the water titration method and pseudoternary phase diagram plots. The interfacial tension between caprylic/capric triglyceride (CCT oil) and water was significantly reduced by the surfactant/co-surfactant combination (Smix) of Cremophore® RH40 and a double-tails co-surfactant, polyglycerol-3-diisostearate, at an HLB of 13 together with a water-to-co-solvent (PG) ratio of 1:1. A two-level full factorial design of experiment (FFD-DoE) emphasized the independent variables of the HLB value, co-solvent, and CCT oil contents affecting the optimal compositions for micro- or nanoemulsion formation. The low-energy spontaneous emulsification of the optimized combination at a low Smix content (10%) yielded the translucent oil-in-water Tripeptide-3 nanoemulsions with an internal droplet size of 25.7 ± 1.20 nm, a narrow polydispersity index of 0.237 ± 0.129, and 70.6 ± 0.58% transmittance. The in vitro skin permeation study revealed a significantly higher skin penetration and retention of the Tripeptide-3 nanoemulsions compared to the high surfactant microemulsions and coarse emulsions. Skin irritation and oil control efficacy were evaluated in healthy volunteers before and after product application for 28 days. The obtained nanoemulsions not only decreased sebum production but also enhanced skin moisture levels. In conclusion, the meticulously designed nanoemulsions, incorporating suitable excipients, show a promising delivery system for hydrophilic peptides to control sebum overproduction in oily facial skin. [ABSTRACT FROM AUTHOR]

Emulsification is one of the important mechanisms of surfactant flooding. To improve oil recovery for low permeability reservoirs, a highly efficient emulsification oil flooding system consisting of anionic surfactant sodium alkyl glucosyl hydroxypropyl sulfonate (APGSHS) and zwitterionic surfactant octadecyl betaine (BS-18) is proposed. The performance of APGSHS/BS-18 mixed surfactant system was evaluated in terms of interfacial tension, emulsification capability, emulsion size and distribution, wettability alteration, temperature-resistance and salt-resistance. The emulsification speed was used to evaluate the emulsification ability of surfactant systems, and the results show that mixed surfactant systems can completely emulsify the crude oil into emulsions droplets even under low energy conditions. Meanwhile, the system exhibits good temperature and salt resistance. Finally, the best oil recovery of 25.45% is achieved for low permeability core by the mixed surfactant system with a total concentration of 0.3 wt% while the molar ratio of APGSHS:BS-18 is 4:6. The current study indicates that the anionic/zwitterionic mixed surfactant system can improve the oil flooding efficiency and is potential candidate for application in low permeability reservoirs. [ABSTRACT FROM AUTHOR]

Spontaneous imbibition (SI) is an important mechanism for enhancing oil recovery in low-permeability reservoirs. Due to the strong heterogeneity, and the non-Darcy flow, the construction of SI model for lowpermeability reservoirs is extremely challenging. Commonly, traditional SI models based on single or averaged capillary tortuosity ignore the influence of heterogeneity of pore seepage channels and the threshold pressure (TP) on imbibition. Therefore, in this work, based on capillary model and fractal theory, a mathematical model of characterizing SI considering heterogeneity of pore seepage channels is established. On this basis, the threshold pressure was introduced to determine the pore radius at which the wetted phase can displace oil. The proposed new SI model was verified by imbibition experimental data. The study shows that for weakly heterogeneous cores with permeability of 0-1 mD, the traditional SI model can characterize the imbibition process relatively accurately, and the new imbibition model can increase the coefficient of determination by 1.05 times. However, traditional model has serious deviations in predicting the imbibition recovery for cores with permeability of 10e50 mD. The new SI model coupling with heterogeneity of pore seepage channels and threshold pressure effectively solves this problem, and the determination coefficient is increased from 0.344 to 0.922, which is increased by 2.68 times. For low-permeability reservoirs, the production of the oil in transitional pores (0.01-0.1 mm) and mesopores (0.1-1 mm) significantly affects the imbibition recovery, as the research shows that when the heterogeneity of pore seepage channels is ignored, the oil recovery in transitional pores and mesopores decreases by 7.54% and 4.26%, respectively. Sensitivity analysis shows that increasing interfacial tension, decreasing contact angle, oilewater viscosity ratio and threshold pressure will increase imbibition recovery. In addition, there are critical values for the influence of these factors on the imbibition recovery, which provides theoretical support for surfactant optimization. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the tragacanth gum potential as a natural polymer combined with natural clay mineral (montmorillonite, kaolinite, and illite) nanoparticles (NPs) to form NPepolymer suspension for enhanced oil recovery (EOR) in carbonate reservoirs. Thermal gravimetric analysis (TGA) tests were conducted initially in order to evaluate the properties of tragacanth gum. Subsequently, scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) tests were used to detect the structure of clay particles. In various scenarios, the effects of natural NPs and polymer on the wettability alteration, interfacial tension (IFT) reduction, viscosity improvement, and oil recovery were investigated through contact angle system, ring method, AntonPaar viscometer, and core flooding tests, respectively. The entire experiment was conducted at 25, 50, and 75 °C, respectively. According to the experimental results, the clay minerals alone did not have a significant effect on viscosity, but the addition of minerals to the polymer solution leads to the viscosity enhancement remarkably, resulting mobility ratio improvement. Among clay NPs, the combination of natural polymer and kaolinite results in increased viscosity at all temperatures. Considerable wettability alteration was also observed in the case of natural polymer and illite NPs. Illite in combination with natural polymer showed an ability in reducing IFT. Finally, the results of displacement experiments revealed that the combination of natural polymer and kaolinite could be the best option for EOR due to its substantial ability to improve the recovery factor. [ABSTRACT FROM AUTHOR]

To achieve better process control of silicon (Si) alloy production using aluminum as a reductant of calcium silicate (CaO-SiO2) slag, it is necessary to understand the reaction phenomena concerning the behavior of formed phases at the metal-slag interface during conversion. The interfacial interaction behavior of non-agitated melt was investigated using the sessile drop method for varying time and temperature, followed by EPMA phase analysis at the vicinity of the metal–slag interface. The most remarkable features of the reaction were the accumulation of solid calcium aluminate product layers at the Al alloy–slag interface and spontaneous emulsion of Si-alloy droplets in the slag phase. The reduction is strictly limited at 1550 °C due to the slow transfer of calcium aluminates away from the metal-slag interface into the partially liquid bulk slag. Reduction was significantly improved at 1600–1650 °C despite an interfacial layer being present, where the conversion rate is most intense in the first minutes of the liquid–liquid contact. A high mass transfer rate across the interface was shown related to the apparent interfacial tension depression of the wetting droplet along with a significant perturbed interface and emulsion due to Kelvin–Helmholtz instability driven by built-up interfacial charge at the interface. The increased reaction rate observed from 1550 °C to 1600–1650 °C for the non-agitated melt was attributed to the advantageous physical properties of the slag phase, which can be further regulated by the stoichiometry of metal–slag interactions and the composition of the slag. [ABSTRACT FROM AUTHOR]

Emulsion polymerization is an effective means of synthesizing high-molecular-weight polymers in order to reduce the consumption of fossil energy. This paper adopts isoamyl octanoate to replace white oil as the continuous phase of emulsion polymerization to synthesize the high molecular weight polyacrylamide emulsion RSE. S-80 and T-80 were chosen as the emulsifiers, and the test results showed that the HLB value is 5.72 when S-80/T-80 is 6.5. When S-80/T-80 is 6.5, the HLB value is 5.72. Water and isoamyl octanoate can produce ultra-low interfacial tension and stable arrangement in the interfacial membrane to form a stable emulsion, and the particle size is uniformly distributed in a normal manner. The test of the exothermic process of polymerization shows that the emulsion can be stabilized into nuclei, and polyacrylamide polymers with a molar mass of more than 18 million are obtained. The microstructure test observes that RSE molecules are in an aggregated state in the aqueous solution. A three-dimensional spatial network structure is formed, and the polymerization can be stabilized in a three-dimensional network structure after 120 °C, 170 s−1 shear, which still has good stability. After the variable shear performance test proved that the aqueous solution of RSE belongs to the typical non-Newtonian fluids, to shock test the viscoelasticity of different concentrations of RSE polymer, G′ > G″, the RSE solution to elasticity is dominant. In this paper, the capacity to form stable emulsions of isoamyl octanoate in the emulsion polymerization process is investigated to provide a basis for seeking the selection of a continuous phase with little environmental pollution and high functionality. [ABSTRACT FROM AUTHOR]

BACKGROUND: Okara cellulose is a highly abundant, green, sustainable, and biodegradable polymer with many potential industrial applications. In this study, we fabricated composite hydrogels with okara cellulose nanofibers (CNFs) and chitosan (CH) by hydrating, sonicating, and heating them at 100 °C for 30 min, and then induced their assembly by cooling. The effects of okara CNF (with and without 2,2,6,6‐tetramethylpiperidinyloxy (TEMPO) oxidation) and CH concentration on the structure and properties of the hydrogels was examined, including their microstructure, surface properties, rheological properties, and thermal stability. RESULTS: Our results indicate that there was an electrostatic attraction between the anionic okara CNF and cationic CH, which facilitated hydrogel formation. The surface, textural, rheological, and thermal stability properties were better for the composite hydrogels than for the single CH ones, as well as for the CNF that had undergone TEMPO oxidation. For the TC‐CH hydrogels, the contact angle was 39.5°, the interfacial tension was 69.1 mN m−1, and the surface tension was 1.44 mN m−1. CONCLUSION: In this study, the novel hydrogels developed may be useful as a soft material in a range of applications in foods, supplements, health care products, cosmetics, and drugs. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Spontaneous imbibition is one of the important means to enhance oil recovery in low permeability reservoirs, and it has good field application effects. Through the interfacial tension (IFT), contact angle (CA), and adsorption experiments, the effects of SDBS surfactant on IFT and reservoir wettability were studied, and the adsorption rule of SDBS at the mineral surface was obtained. On this basis, the imbibition recovery and mechanism of cores with different permeability are studied. The study showed that in low permeability reservoir, gravity and capillary force are the main controlling factors of imbibition. In the early stage, gravity determines the recovery, because the imbibition rate is 2.75 times that dominated by capillary force. The capillary force can continue to produce oil in small pores, and the imbibition time is twice that of gravity, which determines the recovery in the late imbibition stage. Therefore, the synergistic effect of gravity and capillary force can optimize the imbibition recovery, in low permeability reservoirs. When the concentration of SDBS solution is CMC (0.1%), due to the mineral interface adsorbs, the capillary force decreases by 10.76%, and the adhesion work increases by 3.42 times, resulting in a decrease in the imbibition recovery. The imbibition driving force is different for different reservoir properties, which can be adjusted by adding a surfactant to change IFT and CA. [ABSTRACT FROM AUTHOR]

In this study, the effect of salinity on the enhanced oil recovery process in the presence of commercial silica nanoparticles and a new synthesized polymeric ZnO/SiO2/Xhantan nanocomposites (NCs) at reservoir conditions were investigated. First, the crystal structure and morphology of the NCs were investigated using x-ray diffraction, Scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller, and energy-dispersive x-ray. Then, the effect of silica nanoparticles and NCs on the change of wettability and interfacial tension at different salinities and reservoir conditions was studied. For 2 SW (seawater) and 10 SW (two times diluted seawater), silica and NCs decreased contact angle from (79 °, 75 °) to (78 °, 74 °) and (70 °, 62 °), respectively. Zeta potential results are −31.37 and −28.00 for 10 SW and 2 SW concentrations, which show the perfectly stable and relatively stable regions, respectively. Moreover, interfacial tension was decreased more in the presence of 10 SW in comparison to 2 SW, and the oil recovery at 2 SW and 10 SW concentrations were 51.71% and 70.25%, respectively, at 0.05 wt% NCs concentration which main reasons are improving wettability, interfacial tension, and stability. [ABSTRACT FROM AUTHOR]

We numerically investigate the pressure drop reduction (PDR) performance of microchannels equipped with liquid-infused surfaces, along with determining the shape of the interface between the working fluid and lubricant within the microgrooves. The effects of different parameters, such as the Reynolds number of working fluid, density and viscosity ratios between the lubricant and working fluid, the ratio of the thickness of the lubricant layer over the ridges to the depth of the groove, and the Ohnesorge number as a representative of the interfacial tension, on the PDR and interfacial meniscus within the microgrooves are comprehensively studied. The results reveal that the density ratio and Ohnesorge number do not significantly affect the PDR. On the other hand, the viscosity ratio considerably affects the PDR, and a maximum PDR of 62% compared to a smooth non-lubricated microchannel is achieved for a viscosity ratio of 0.01. Interestingly, the higher the Reynolds number of the working fluid, the higher the PDR. The meniscus shape within the microgrooves is strongly affected by the Reynolds number of the working fluid. Despite the insignificant effect of interfacial tension on the PDR, the interface shape within the microgrooves is appreciably influenced by this parameter. [ABSTRACT FROM AUTHOR]

[Display omitted] Understanding and manipulating the oil/water interface is important across various industries, including food, pharmaceuticals, cosmetics, and detergents. Many of these processes occur under elevated pH conditions in buffer systems, where base-catalyzed hydrolysis of triglyceride ester bonds leads to amphiphilic reaction products such as fatty acids. Here, pH-triggered alterations of the triolein/water interface are analyzed in the presence of phosphate (PB) and tris(hydroxymethyl)aminomethane (TRIS). Ellipsometry at the liquid/liquid interface, tensiometry, and scanning small angle X-ray scattering are used to study the formation of structures at the oil/water interface. Confocal Raman microscopy, nuclear magnetic resonance spectroscopy, and in silico modeling analyze compositional changes in the interfacial region. pH and buffer ions were discovered to significantly modify the triglyceride/water interface, contrary to the decane/water control. Decreasing interfacial tensions from 32.4 to 2.2 mN/m upon pH increase from 6.5 to 9.5 is seen with multilamellar interfacial layers forming at pH around 9.0 in the presence of TRIS. Oleic acid from triolein hydrolysis and its further interaction with TRIS is held responsible for this. The new understanding can guide the design of pH- and ion-responsive functional materials and optimize industrial processes involving triglyceride/water interfaces. [ABSTRACT FROM AUTHOR]

The interfacial behavior of tetrabutylammonium bromide (TBAB) aqueous solutions in the absence of gas and the presence of methane and carbon dioxide gases is studied by molecular dynamics simulations. The aqueous TBAB phase, at concentrations similar to the solid semiclathrate hydrate (1:38 mol ratio), has a smaller interfacial tension and an increase in the gas molecules adsorbed at the interface compared to that in pure water. Both these factors may contribute to facilitating the uptake of the gases into the solid phase during the process of semiclathrate hydrate formation. At similar gas pressures, CO2 is adsorbed preferentially compared to CH4, giving it a higher surface density, due to the stronger intermolecular interactions of CO2 molecules of the solution at the interface. The increase in relative adsorption of CH4 at the solution surface compared to that in pure water surface is due to the hydrophobic interactions between the n-alkyl chains of the TBA+ cation and methane gas. [ABSTRACT FROM AUTHOR]

The study demonstrates the significant enhancement in oil production from a Romanian oil field using alkali–polymer (AP) flooding for reactive viscous oil. We conducted comprehensive interfacial tension (IFT) measurements across various alkali and AP concentrations, along with phase behavior assessments. Micromodel flooding experiments were used to examine pore-scale effects and select appropriate chemical concentrations. We tested displacement efficiency at the core level and experimented with different sequences and concentrations of alkali and polymers to minimize costs while maximizing the additional recovery of reactive viscous oil. The IFT analysis revealed that saponification at the oil–alkali interface significantly lowers IFT, but IFT gradually increases as soap diffuses away from the interface. Micromodels indicated that polymer or alkali injection alone achieve only minimal incremental recovery beyond waterflooding. However, AP flooding significantly enhanced incremental oil recovery by efficiently moving the mobilized oil with the viscous fluid and increasing exposure of more oil to the alkali solution. Coreflood experiments corroborated these findings. We also explored how divalent cations influence polymer concentration selection, finding that softening the injection brine significantly increased the viscosity of the AP slug. [ABSTRACT FROM AUTHOR]

BACKGROUND: Protein‐based nanoparticles have gained considerable interest in recent years due to their biodegradability, biocompatibility, and functional properties. However, nanoparticles formed from hydrophobic proteins are prone to instability under environmental stress, which restricts their potential applications. It is therefore of great importance to develop green approaches for the fabrication of hydrophobic protein‐based nanoparticles and to improve their physicochemical performance. RESULTS: Gliadin/shellac complex nanoparticles (168.87 ~ 403.67 nm) with various gliadin/shellac mass ratios (10:0 ~ 5:5) were prepared using a pH‐driven approach. In comparison with gliadin nanoparticles, complex nanoparticles have shown enhanced stability against neutral pH, ions, and boiling. They remained stable under neutral conditions at NaCl concentrations ranging from 0 to 100 mmol L−1 and even when boiled at 100 °C for 90 min. These nanoparticles were capable of effectively reducing oil–water interfacial tension (5 ~ 11 mNm−1) but a higher amount of shellac in the nanoparticles compromised their ability to lower interfacial tension. Moreover, the wettability of the nanoparticles changed as the gliadin/shellac mass ratio changed, leading to a range of three‐phase contact angles from 52.41° to 84.85°. Notably, complex nanoparticles with a gliadin/shellac mass ratio of 8:2 (G/S 8:2) showed a contact angle of 84.85°, which is considered suitable for the Pickering stabilization mechanism. Moreover, these nanoparticles exhibited the highest emulsifying activity of 52.42 m2 g−1 and emulsifying stability of 65.33%. CONCLUSIONS: The findings of the study revealed that gliadin/shellac complex nanoparticles exhibited excellent resistance to environmental stress and demonstrated superior oil–water interfacial behavior. They have strong potential for further development as food emulsifiers or as nano‐delivery systems for nutraceuticals. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The oil/water interfacial tension plays a crucial role in tertiary oil recovery, and the low interfacial tension facilitates oil emulsification and stripping. Here, anionic surfactant sodium dodecyl sulfate and cationic surfactant hexadecyltrimethylammonium bromide were employed to study their ability to reduce the oil/water interfacial tension (IFT). Experimental results show that the mixed cationic and anionic surfactants could produce lower IFT than that of individual cationic or anionic surfactant, and the lowest IFT could be obtained at molar ratio of CTAB:SDS = 2:1. Employing molecular dynamics simulation method, the oil/water IFT was calculated and gave same changing trend with that of the experiment. The underlying mechanism of IFT modulated by mixed cationic and anionic surfactants was unveiled from the insight of interfacial structure, interfacial energy, interaction energy between different molecules and interface roughness, and so on. We found the hydration radius of counterion as well as the charge distribution of polar headgroup of surfactant together play crucial role determining the ion distribution inside water phase and surfactant/water interface, and further influencing the IFT. Our study provides an atomic-level understanding of the IFT modulated by cationic and anionic surfactants, and our results might have some references for enhanced oil recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] Plant protein ingredients from similar sources can vary in functionality not only because of compositional differences, but also because of differences in their structure depending on their processing history. It is essential to understand these distinctions to develop novel food emulsion using plant proteins. It is hypothesized that differing interfacial properties can be attributed to their structures, aggregation, and colloidal states. The adsorption behavior of a commercial protein isolate, homogenized or non-homogenized, was compared to a mildly extracted isolate to evaluate the effect of aggregation state and structural differences. After characterization of the particle size and protein composition, the interfacial properties were compared. Atomic force microscopy provided evidence of interfaces packed with protein oligomers regardless of the treatment. Differences in adsorption kinetics and interfacial shear rheology depending on oil polarity suggested different interfacial structures. A polydisperse mixture of protein oligomers resulted in increased rearrangements and protein-protein interactions at the interface. Homogenization of commercial proteins resulted in a lower interfacial tension and less elastic interfaces compared to those of native proteins due to the presence of larger aggregates. This study highlights how the interfacial properties can be related to the protein aggregation state resulting from differences in processing history. [ABSTRACT FROM AUTHOR]

[Display omitted] Sessile droplets solubilizing in surfactant solution are frequently encountered in practice, but the factors governing their non-equilibrium dynamics are not well understood. Here, we investigate mechanisms by which solubilizing, sessile oil droplets in aqueous surfactant solution dewet from hydrophobic substrates and spread on hydrophilic substrates. We quantify the dependence of droplet contact line dynamics on drop size and oil, surfactant, and substrate chemistries. We consider halogenated alkane oils as well as aromatic oils and focus on common nonionic nonylphenol ethoxylate surfactants. We correlate these results with measurements of the interfacial tensions. Counter-intuitively, under a range of conditions, we observe complete dewetting of oil from hydrophobic substrates but spreading on hydrophilic substrates. The timescales needed to reach a steady-state contact angle vary widely, with some droplets examined taking over a day. We find that surfactant surface adsorption governs the contact angle on shorter timescales, while partitioning of surfactant from water to oil, and oil solubilization into the water, act on longer timescales to facilitate the complete dewetting. Understanding of the role played by surfactant and oil transport presents opportunities for tailoring sessile droplet behaviors and controlling droplet dynamics under conditions that would previously not have been considered. [ABSTRACT FROM AUTHOR]