Search

In a recent work, we have briefly introduced a new structural index for water that, unlike previous indicators, was devised specifically for generic contexts beyond bulk conditions, making it suitable for hydration and nanoconfinement settings. In this work, we shall study this metric in detail, demonstrating its ability to reveal the existence of a fine-tuned interplay between the local structure and energetics in liquid water. This molecular principle enables the establishment of an extended hydrogen bond network, while simultaneously allowing for the existence of network defects by compensating for uncoordinated sites. By studying different water models and different temperatures encompassing both the normal liquid and the supercooled regime, this molecular mechanism will be shown to underlie the two-state behavior of bulk water. In addition, by studying functionalized self-assembled monolayers and diverse graphene-like surfaces, we shall show that this principle is also operative at hydration and nanoconfinement conditions, thus generalizing the validity of the two-liquid scenario of water to these contexts. This approach will allow us to define conditions for wettability, providing an accurate measure of hydrophobicity and a reliable predictor of filling and drying transitions. Hence, it might open the possibility of elucidating the active role of water in the broad fields of biophysics and materials science. As a preliminary step, we shall study the hydration structure and hydrophilicity of graphene-like systems (parallel graphene sheets and carbon nanotubes) as a function of the confinement dimensionality. [ABSTRACT FROM AUTHOR]

Moving contact line dynamics calculations include two models: precursor film models and slip models. The lubrication approximation method is used to establish a three-dimensional mathematical model to analyze the droplet thermocapillary migration behavior on a non-uniformly heated solid substrate with a wettability track. The contact line dynamics in the slip model and the disjoining pressure effect in the precursor model are proposed to regulate the substrate wettability. Both models are numerically implemented to investigate droplet spreading for three cases: free spreading on an isothermal substrate, thermocapillary migration on a uniform wettability substrate, and thermocapillary migration on a wettability-confined track. For the case of free spreading on an isothermal substrate, the three-dimensional results of the slip and precursor contact line models are essentially consistent with two-dimensional slip model results. For the case of thermocapillary migration on a uniform wettability substrate, the results of the two models essentially agree with the experimental results. Decreasing the thermal gradient reduces the discrepancies between the two models that result from the coordinate transformation method used in the slip model, which reduces the contact angles measured in the y-direction and enlarges the advancing contact angle in the migration direction. For the case of thermocapillary migration on a wettability-confined track, the slip model gradually shows a "dynamic-pinning" behavior with increasing equilibrium contact angle in the hydrophobic region. By contrast, the precursor film model maintains a stationary pinning behavior but separates a residual liquid outside the track. The precursor film model is preferred over the slip model in lubrication approximations for three-dimensional fluids when calculating complex moving contact dynamics caused by wettability differences. However, the precursor film model must be further optimized to prevent numerical instability. [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]

When a contact line (CL)—where a liquid–vapor interface meets a substrate—is put into motion, it is well known that the contact angle differs between advancing and receding CLs. Using non-equilibrium molecular dynamics simulations, we reveal another intriguing distinction between advancing and receding CLs: while temperature increases at an advancing CL—as expected from viscous dissipation, we show that temperature can drop at a receding CL. Detailed quantitative analysis based on the macroscopic energy balance around the dynamic CL showed that the internal energy change of the fluid due to the change of the potential field along the pathline out of the solid–liquid interface induced a remarkable temperature drop around the receding CL, in a manner similar to latent heat upon phase changes. This result provides new insights for modeling the dynamic CL, and the framework for heat transport analysis introduced here can be applied to a wide range of nanofluidic systems. [ABSTRACT FROM AUTHOR]

Directional wicking and spreading of liquids can be achieved by regular micro-patterns of specifically designed topographic features that break the reflection symmetry of the underlying pattern. The present study aims to understand the formation and stability of wetting films during the evaporation of volatile liquid drops on surfaces with a micro-pattern of triangular posts arranged in a rectangular lattice. Depending on the density and aspect ratio of the posts, we observe either spherical-cap shaped drops with a mobile three-phase contact line or the formation of circular or angular drops with a pinned three-phase contact line. Drops of the latter class eventually evolve into a liquid film extending to the initial footprint of the drop and a shrinking cap-shaped drop sitting on the film. The drop evolution is controlled by the density and aspect ratio of the posts, while no influence of the orientation of the triangular posts on the contact line mobility becomes evident. Our experiments corroborate previous results of systematic numerical energy minimization, predicting that conditions for a spontaneous retraction of a wicking liquid film depend weakly on the orientation of the film edge relative to the micro-pattern. [ABSTRACT FROM AUTHOR]

Inkjet-printed micro-patterns on hydrophobic surfaces have promising applications in the fabrication of microscale devices such as organic thin-film transistors. The low wettability of the surface prevents the inkjet-printed droplets from spreading, connecting to each other, and forming a pattern. Consequently, it is challenging to form micro-patterns on surfaces with low wettability. Here, we propose a sequential printing and drying method to form micro-patterns and control their shape. The first set of droplets is inkjet-printed at a certain spacing and dried. The second set of droplets is printed between these dry anchors on the surface with low wettability. As a result, a stable bridge on the surface with low wettability forms. This printing method is extended to more complicated shapes such as triangles. By implementing an energy minimization technique, a simple model was devised to predict the shape of the inkjet-printed micro-patterns while confirming that their equilibrium shape is mainly governed by surface tension forces. The gradient descent method was utilized with parametric boundaries to emulate droplet pinning and wettability of the anchors and to prevent convergence issues from occurring in the simulations. Finally, the energy minimization based simulations were used to predict the required ink to produce dry lines and triangles with smooth edges. [ABSTRACT FROM AUTHOR]

Large contact angle hysteresis surfaces were the topic of a contribution in Ref. [19]. They address the relation between vapor of a liquid, a finite contact angle, and a possible wetting transition at saturation vapor pressure. In Ref. [15], the authors apply surfaces with low contact angle hysteresis to the evaporation of drops of salt solutions. Low contact angle hysteresis implies that contact lines or sessile drops move without much resistance. [Extracted from the article]

We develop and harness a phase field simulation method to study liquid filling on grooved surfaces. We consider both short-range and long-range liquid–solid interactions, with the latter including purely attractive and repulsive interactions as well as those with short-range attraction and long-range repulsion. This allows us to capture complete, partial, and pseudo-partial wetting states, demonstrating complex disjoining pressure profiles over the full range of possible contact angles as previously proposed in the literature. Applying the simulation method to study liquid filling on grooved surfaces, we compare the filling transition for the three different classes of wetting states as we vary the pressure difference between the liquid and gas phases. The filling and emptying transitions are reversible for the complete wetting case, while significant hysteresis is observed for the partial and pseudo-partial cases. In agreement with previous studies, we also show that the critical pressure for the filling transition follows the Kelvin equation for the complete and partial wetting scenarios. Finally, we find the filling transition can display a number of distinct morphological pathways for the pseudo-partial wetting cases, as we demonstrate here for varying groove dimensions. [ABSTRACT FROM AUTHOR]

We investigate the wetting properties of PDMS (Polydimethylsiloxane) pseudo-brush anchored on glass substrates. These PDMS pseudo-brushes exhibit a significantly lower contact angle hysteresis compared to hydrophobic silanized substrates. The effect of different molar masses of the used PDMS on the wetting properties seems negligible. The surface roughness and thickness of the PDMS pseudo-brush are measured by atomic force microscopy and x-ray reflectivity. The outcome shows that these surfaces are extremely smooth (topologically and chemically), which explains the reduction in contact angle hysteresis. These special features make this kind of surfaces very useful for wetting experiments. Here, the dynamics of the four-phase contact point are studied on these surfaces. The four-phase contact point dynamics on PDMS pseudo-brushes deviate substantially from its dynamics on other substrates. These changes depend only a little on the molar mass of the used PDMS. In general, PDMS pseudo-brushes increase the traveling speed of four-phase contact point on the surface and change the associated power law of position vs time. [ABSTRACT FROM AUTHOR]

On homogeneous substrates, droplets can slide due to external driving forces, such as gravity, whereas in the presence of wettability gradients, sliding occurs without external forces since this gradient gives rise to an internal driving force. Here, we study via molecular dynamics simulations the more complex behavior when droplets are driven under the combined influence of an external and internal driving force. For comparison, the limiting cases of a single driving force are studied as well. During a large part of the sliding process over the borderline of both substrates, separating both wettabilities, the velocity is nearly constant. When expressing it as the product of the effective mobility and the effective force, the effective mobility mainly depends on the mobility of the initial substrate, experienced by the receding contact line. This observation can be reconciled with the properties of the flow pattern, indicating that the desorption of particles at the receding contact line is the time-limiting step. The effective force is the sum of the external force and a renormalized internal force. This renormalization can be interpreted as stronger dissipation effects when driving occurs via wettability gradients. [ABSTRACT FROM AUTHOR]

The realization of nanoscale devices largely depends on our ability to control and manipulate interfacial interactions and, thus, understanding of the mechanisms of surface/interface instabilities. In this work, theoretically as well as technologically important and distinct two thermodynamic systems, which are exposed to (isobaric) and isolated from (isochoric) external body forces and surface tractions, are formulated by using irreversible thermodynamics in combination with the generalized variational method. The starting point for the present formulation closely follows up the Fowler and Guggenheim [Statistical Thermodynamics (University Press, Cambridge, 1952)] interpretation of the Planck inequality [Über Prinzip Vermehrung Entropie: Ann. Phys. Series 2(32), 462 (1887)] for isothermal reversible and irreversible (natural) infinitesimal changes in heterogeneous systems (multi-phase and multi-component). By combining this fundamental principle with the interlink between the dissipation function and global internal entropy production postulates, two distinct sets of governing equations for the surface drift-diffusion flux as well as the rate of evaporation/condensation and/or the growth/recrystallization of amorphous solid thin films are obtained for isochoric and isobaric systems. The role of Eshelby's energy-momentum tensor in the generalized potential for the interface displacement is found to differ (opposite in sign) for isochoric and isobaric systems. To demonstrate the importance of these sign conflicts, two sets of computer experiments are performed on isochoric and isobaric systems. They showed us that the elastic strain energy density contribution to the generalized driving force for surface drift-diffusion alone favoring flat and smooth surfaces in isobaric systems regardless of the sign of the uniaxial stress (healing), rather than causing the surface roughness and even catastrophic crack initiation as the case in internally strained isochoric systems. Computer simulations allowed us to track down the dynamical behavior of test modules by furnishing surface and strain energy variations, combined with the Global Helmholtz free change, which indicates the existence of two regimes: initial smooth surface undulations followed up by the rather chaotic crack formation and propagation stage at the middle of the thin film supported by the stiff substrate. In this study, we mainly focused on the development kinetics of "Stranski–Krastanow" island-type morphology, initiated by the nucleation route rather than the surface roughening scheme. The physicomathematical model, which is based on the irreversible thermodynamics treatment of surfaces and interfaces with singularities [T. O. Ogurtani, J. Chem. Phys. 124, 144706 (2006)], furnishes us to have autocontrol on otherwise free-motion of the triple junction contour line between the substrate and the droplet without presuming any equilibrium dihedral contact (wetting) angles at edges. We have also demonstrated the formation of the Stranski–Krastanow (SK)-type doublet islanding (quantum dots) as a stationary nonequilibrium state in an epitaxially strained thin flat droplet on a rigid substrate by introducing the wetting potential—invoked by the quantum confinement—into the scenario and carefully selecting the system parameters (size and shape) for the isochoric system represented by [Ge/Si (100)]. It has been also shown that on the contrary to common perceptions, the Stranski–Krastanow islands are in genuine stationary nonequilibrium states in the sense of Prigogine if one invokes proper free-moving boundary conditions at triple junctions deduced from the irreversible thermodynamics rather than ad hoc periodic or reflecting constrains at the edges. [ABSTRACT FROM AUTHOR]

The relation between wetting properties and geometric parameters of fractal surfaces are widely discussed on the literature and, however, there are still divergences on this topic. Here we propose a simple theoretical model to describe the wetting properties of a droplet of water placed on a hierarchical structured surface and test the predictions of the model and the dependence of the droplet wetting state on the initial conditions using simulation of the 3-spin Potts model. We show that increasing the auto-similarity level of the hierarchy – called n – does not affect considerably the stable wetting state of the droplet but increases its contact angle. Simulations also explicit the existence of metastable states on this type of surfaces and shows that, when n increases, the metastability becomes more pronounced. Finally we show that the fractal dimension of the surface is not a good predictor of the contact angle of the droplet. [ABSTRACT FROM AUTHOR]

The high-strength joining of reaction-bonded silicon carbide (RBSC) is pivotal for its application in the semiconductor field. In this paper, the wetting and joining mechanism of Ti–Si eutectic alloy on RBSC were investigated. The contact angles observed between Ti–Si eutectic alloy and RBSC were approximately 1.9°, indicating the favorable wettability and demonstrating the feasibility of bonding RBSC joints. The temperature bending strength of the joints initially increased and then decreased as the brazing temperature increased. Moreover, the shear strength of approximately 107.38 ± 5.56 MPa was achieved at 1350 °C for 30 min. Notably, the diffusion and amalgamation of atoms, lead to the establishment of stronger bonds between adjacent particles. Thus, the Ti–Si eutectic alloy brazing filler formed a direct connection with the RBSC matrix, with Si 2 Ti infiltrating into the base metal on both sides. The utilization of Ti–Si eutectic alloy brazing filler in RBSC joints exhibits promising prospects. [ABSTRACT FROM AUTHOR]

[Display omitted] Water wetting induced corrosion is the core issue for uncovering the corrosion mechanism in multiphase flow environments, relevant to many industrial applications. Here, we experimentally investigated the dynamic failure of an oil film attached on the pre-wetted model surfaces by the electrochemical current detection using an "Alternate Wetting Cell" and the direct visualization of near-wall fluid states. The oil pre-wetted surface performed a superior corrosion mitigation efficiency, exhibiting a protective oil film with a duration time at least 5 times longer than the water pre-wetted surface. It confirms that the oil film rupture is a combined process of the local penetration and pinning of micro-droplets and the phase redistribution of the near-wall fluids. Corrosion finally initiates and propagates on the surface once the droplets pin there or damage the oil film. The result suggests new control strategies for materials corrosion in complex systems by surface modification and fluid management. [ABSTRACT FROM AUTHOR]

Spreading of liquids on soft solids often occurs intermittently, i.e., the liquid's wetting front switches between sticking and slipping. Studies of this so-called stick-slip wetting on soft solids mostly are confined within quasi-static or forced spreading conditions. In these situations, because the sticking duration is set much larger than the viscoelastic relaxation time of the solid, a ridge is persistently and fully developed at the wetting front as the soft solid yields to the liquid's surface tension. The sticking duration and spreading velocity, therefore, were shown to have little impact to the contact angle change required for stick-to-slip transitions. For unsteady wetting of soft solids, a commonly encountered but largely unexplored situation, we hypothesize that the stick-to-slip transition is controlled not only by a combination of sticking duration and the spreading velocity, but also by an increasing depinning threshold caused by the growing ridge at the wetting front. We performed unsteady wetting experiment on soft solids by letting water droplets spread freely on soft solid surfaces of various stiffness. We capture both the stick-slip spreading behavior and growing wetting ridges using synchronous high-speed imaging and high-speed interferometry. Recorded data of liquid spreading and solid deforming at the wetting front were analyzed to shed light on the relation between stick-slip characteristics and the growing wetting ridge. We find that intermittent wetting on a soft solid surface results from a competition between three key factors: liquid inertia, capillary force change during sticking, and growing pinning force caused by the solid's viscoelastic response. We theoretically formulate their quantitative contributions to predict how stick-to-slip transitions occur, i.e., how the contact angle change and sticking duration depend on the liquid's spreading velocity and the solid's viscoelastic characteristics. This provides a mechanistic understanding and methods to control unsteady wetting phenomena in diverse applications, from tissue engineering and fabrication of flexible electronics to biomedicine. [ABSTRACT FROM AUTHOR]

The resource utilization of fly ash has always been a popular topic in the field of solid waste recycling. This paper is based on the three-phase reaction system of "fly ash (s)-[Ca(OH)2–H2O/ethanol] (l)-CO2 (g)", using the bubble carbonization method to carry out heterogeneous phase reaction with fly ash as the core crystallized to form a fly ash-based calcium carbonate composite with higher brightness. The composite material is used in the filling of paper instead of calcium carbonate filler. Based on the previous research of our team, we focused on exploring the addition of miscible wettability additives (ethanol and acetone) to improve the wettability of the reaction system, thereby improving the whitening and modification effect of fly ash. The results showed that the addition of ethanol and acetone can significantly improve the coating effect of fly ash, however, acetone is slightly toxic, more volatile, and expensive than ethanol, so ethanol is more suitable as a wetting agent to be added to the reaction system. Under the optimal coating conditions, when the ratio of ethanol and water is 1:1, the brightness of fly ash can reach 71.62 % ISO, which is 17.29 % ISO higher than that without ethanol. [ABSTRACT FROM AUTHOR]

This paper explores the impact of viscosity ratio and surface wettability on immiscible viscous fingering instability within a rectangular channel. Numerical investigations are conducted across a range of viscosity ratios (VR) from 0.0009 to 0.5 and wall wettability (θ) from 15° to 150°. The volume of fluid (VOF) model is employed to track the development of finger-shaped instability at the fluid interface. Our results indicate that higher viscosity ratios lead to increased displacement efficiency. Additionally, we find the formation of necking at low VR, which diminishes at higher VR values. The finger-shaped pattern splits into two parts at a wettability of 15°; beyond this threshold, no such splitting occurs. Furthermore, a transition from hydrophilic to superhydrophobic wettability abolishes necking, resulting in enhanced displacement efficiency. Notably, as wettability shifts from hydrophilic to super hydrophobic, instability shifts toward the left side. These findings hold relevance for applications in drug delivery, clinical processes and oil recovery. [ABSTRACT FROM AUTHOR]

Experimental studies were conducted on the evaporation rate of a droplet located on the surfaces of various composite and textured materials with different wettability at varying surface temperatures. The maximum droplet evaporation rate was recorded on a textured Cu–SiC composite material with superhydrophilic properties. The minimum droplet evaporation rate corresponded to a superhydrophobic AlMg3 substrate obtained using laser texturing with subsequent hydrophobization procedure. An increase in surface temperature led to a significant deterioration of hydrophobicity for a superhydrophobic substrate and a deterioration of hydrophilicity for a superhydrophilic substrate. As a result, with increasing temperature, the influence of the droplet geometry determined by surface wettability on the droplet evaporation rate for these substrates sharply decreases. Advancing and receding dynamic contact angles, as well as contact angle hysteresis were obtained on all studied substrates. It is generally accepted that a hydrophobic surface exhibits less contact angle hysteresis than a hydrophilic one. However, Cu-SiС composite substrate with a textured hydrophobic surface exhibited the opposite behavior. The contact angle hysteresis on the hydrophobic textured surface was found to be four times higher than that on the hydrophilic polished one. A mechanism was proposed that explains the high contact angle hysteresis and four hysteresis time modes. The minimum hysteresis value corresponded to the superhydrophobic AlMg3 substrate. Anti-corrosion properties were studied for all substrates under consideration. The minimum corrosion current corresponded to a copper substrate with a graphene coating, as well as a superhydrophobic AlMg3 substrate. For a given substrate, there are two corrosion modes with a three-fold difference in the corrosion current. In addition, the wettability behavior of different surfaces was examined using molecular dynamics simulations. The simulation results were found to be consistent with the experimental data. [ABSTRACT FROM AUTHOR]

In this work, alumina foam ceramics (AFC) were prepared by foaming method, and AFC/salt composite phase change materials were prepared by melt infiltration method using AFC as skeleton materials. The results showed that AFC had good chemical compatibility with Na 2 SO 4 and NaCl. The salt contents of AFC/Na 2 SO 4 and AFC/NaCl were 37.8 wt% and 31.7 wt%, respectively, with compressive strength of 100.1 MPa and 72.8 MPa, thermal conductivity of 5.53 W/m·K and 6.40 W/m·K, and energy density of 1129 J/g and 1019 J/g, respectively. Due to the better wettability, AFC and Na 2 SO 4 form a chimeric structure, which has better binding and bonding strength, and is not prone to molten salt leakage. AFC/ Na 2 SO 4 is expected to be applied to industrial waste heat recovery and solar thermal power generation with periodic temperature changes. [ABSTRACT FROM AUTHOR]

The wetting behavior of the Sn-Zr/ZrO 2 system was investigated by different drop methods, and the influencing of temperature and Zr content on the wetting interfacial microstructure were analyzed using SEM, XRD, and TEM. The typical wetting interfacial microstructure is: β-Sn+ZrSn 2 /m-ZrO 2 + β-Sn/t-ZrO 2. Temperature and Zr content both influence the interfacial reaction, thereby influencing the wetting of the Sn-Zr alloy on the ZrO 2 surface; however, the impact results are different. The wettability of the Sn-Zr/ZrO 2 system mainly depends on the continuity of the m-ZrO 2 layer and is unaffected by its thickness. When the m-ZrO 2 layer is continuous, the effect of the quantity of ZrSn 2 phases on the wettability begins to be noticed. The diffusion and reaction control model was used to analyze the wetting behavior of Sn-Zr alloy on ZrO 2 surfaces, thus determining that the Sn-Zr/ZrO 2 system is a typical reactive wetting system, with a calculated spreading activation energy of approximately 116.77 kJ/mol. [ABSTRACT FROM AUTHOR]

Wetting of Al 2 O 3 by molten Cu-xTi alloys with wide composition range was deeply studied. The results show that the precipitation of TiO at the interface is depended on the Ti concentration in the alloys as well as the oxygen partial pressure in the atmosphere. When Ti concentration is lower than the critical Ti concentration, the wettability of the system is mainly determined by the precipitated TiO and the adsorption of Ti-O clusters at the interface; conversely, it is mainly determined by the adsorption of Ti-O clusters on the surface of alumina. For the spreading dynamics of: Cu-Ti alloys on the sapphire surface, the existence of two stages were observed: firstly, an initial fast spreading stage, which is mainly limited by the reaction rate of TiO precipitation; followed by a later slow spreading stage, which is mainly limited by the precipitation reaction of Al 2 O, and exhibits a stepwise spreading characteristic. [ABSTRACT FROM AUTHOR]

This study presents a simple approach to modify the wettability of polydimethylsiloxane (PDMS) using graphene oxide (GO). The proposed method involves a series of steps including O2 plasma treatment, APTES functionalization, GO deposition, and substrate washing and drying. The presence of a GO film on the PDMS surface was confirmed by SEM, AFM, FTIR, and GO reduction using HI acid. The GO film significantly improved the water wettability of the PDMS substrates, as evidenced by a drop in water contact angle from 112° to 40°. Over the course of time, the contact angle increases to reach a value of almost 70° after 4 days before finally settling at a steady value of 82° after 9 days. Once this value was reached, no further changes were observed in the contact angle. Even with the increase in the contact angle, the proposed method shows an enhancement in the hydrophilicity of the PDMS of almost 35°. This treatment improved also the wettability of the PDMS under an oil medium where a dispensed water droplet attaches on the GO-coated PDMS surface. The versatility of this method lies in its ability to tune the wettability of PDMS, making it suitable for a diverse range of applications. For instance, it can be used to create flexible hydrophilic membranes for efficient oil/water separation or to fabricate hydrophilic microfluidic chips for biological purposes. Overall, this study offers a simple and effective approach for altering the surface properties of PDMS, expanding its potential for a wide range of applications. [ABSTRACT FROM AUTHOR]

The wettability of polymers is usually inadequate to ensure the appropriate spreading of polar liquids and thus enable the required adhesion of coatings. A standard ecologically benign method for increasing the polymer wettability is a brief treatment with a non-equilibrium plasma rich in reactive oxygen species and predominantly neutral oxygen atoms in the ground electronic state. The evolution of the surface wettability of selected aromatic polymers was investigated by water droplet contact angles deposited immediately after exposing polymer samples to fluxes of oxygen atoms between 3 × 1020 and 1 × 1023 m−2s−1. The treatment time varied between 0.01 and 1000 s. The wettability evolution versus the O-atom fluence for all aromatic polymers followed similar behavior regardless of the flux of O atoms or the type of polymer. In the range of fluences between approximately 5 × 1020 and 5 × 1023 m−2, the water contact angle decreased exponentially with increasing fluence and dropped to 1/e of the initial value after receiving the fluence close to 5 × 1022 m−2. [ABSTRACT FROM AUTHOR]

The influence of wettability on the permeability performance of water–oil two-phase flow has attracted increasing attention. Dispersed flow and stratified flow are two flow regimes for water–oil two-phase flow in capillary fractures. The theoretical models of relative permeability considering wettability were developed for these two water–oil flow regimes from the momentum equations of the two-fluid model. Wettability coefficients were proposed to study the impact of wettability on relative permeabilities. Experiments were conducted to study the relative permeabilities of laminar water–oil two-phase flow in water-saturated and oil-saturated horizontal capillary fractures with different hydraulic diameters. These fractures were made of polymethylmethacrylate (PMMA) and polytetrafluoroethylene (PTFE), which had different surface wettabilities. In this experiment, the regimes are dispersed flow and stratified flow. The results show that the effect of wettability on the relative permeabilities increases as the hydraulic diameters of capillary fractures decrease for water–oil two-phase flow. The relative permeabilities in a water-saturated capillary fracture are higher than those in an oil-saturated capillary fracture of the same material. The relative permeabilities in a PTFE capillary fracture are larger than those in a PMMA capillary fracture under the same saturated condition. Wettability has little effect on the permeability performances of water–oil two-phase flow in water-saturated capillary fractures, but is significant for those in oil-saturated capillary fractures. [ABSTRACT FROM AUTHOR]

Glass-to-metal seals are a very important element in the construction of vacuum tubes, electric discharge tubes, pressure-tight glass windows in metal cases, and metal or ceramic packages of electronic components. This paper presents the influence of different pretreatment methods on the high-temperature wettability of 304 stainless steel by high-alumina glass sealing. The pretreatment of the steel included laser surface melting and pre-oxidizing. The bonding characteristics of glass and stainless steel directly depend on the wettability in terms of the measured wetting angle, the type of oxide formed at the stainless steel surface, and the microstructural changes during the manufacturing process. The oxide film thickness on the stainless steel surface was evaluated to determine the optimal parameters. The film was wetted with high-alumina glass powder at different temperatures. The results showed that pre-oxidation decreased the wetting angle from 56.2° to 33.6°, while for the laser-melted surface, the wetting angle decreased from 49.8° to 31.5°. Scanning electron microscopy (SEM) revealed that the oxide film on the laser-melted surface was thicker and denser than that formed on the pre-oxidized surface. The present work shows that laser surface melting has a greater beneficial influence on the wetting and diffusion characteristics of 304 stainless steel sealed by high-alumina glass. [ABSTRACT FROM AUTHOR]

[Display omitted] Achieving rapid capillary wetting is highly desirable in nature and industries. Previous endeavors have primarily concentrated on passive wetting strategies through surface engineering. However, these approaches are inadequate for high-viscosity fluids due to the significant viscous resistance, especially for non-Newtonian fluids. In contrast, forced wetting emerges as a promising method to address the challenges associated with achieving rapid wetting of non-Newtonian fluids in capillaries. To investigate the forced wetting behavior of viscoelastic fluids in capillaries, we employ Xanthan Gum (XG) aqueous solutions as target fluids with the storage modulus significantly exceeding the loss modulus. We utilize smooth glass capillaries connected to a syringe pump to achieve high moving speeds of up to 1 m/s. Our experiments reveal a significant distinction in the power-law exponent that governs the scaling relationship between the dynamic contact angle and velocity for viscoelastic fluids compared to Newtonian fluids. This exponent is considerably smaller and varies based on the concentration of viscoelastic fluids and the diameter of the capillaries. We suggest that the viscosity dominates the wetting dynamics of viscoelastic fluids, manifested by the contact line morphology-dependent behavior. This insight has significant implications for microfluidics and drug injectability. [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]

Aluminum nitride (AlN), a versatile ceramic with high thermal conductivity, high electrical resistivity, and a coefficient of thermal expansion compatible with silicon, is well‐suited for direct‐to‐chip cooling applications of electronics, implementation in wide bandgap semiconductors, and for high‐temperature heat exchangers. Despite multiple advantages, AlN's implementation in liquid‐cooling applications is often hindered by surface‐degrading effects of working‐fluid‐induced hydrolysis. Herein, a scalable ‐but highly tunable‐ wettability engineering approach is introduced, that allows effective implementation of bulk AlN substrates in enhanced two‐phase cooling of electronics. The approach prevents hydrolysis of AlN by aqueous media and establishes control over surface roughness, all the while maintaining bulk integrity and material properties of the underlying substrate. Demonstration of the new approach is presented in spontaneous, pumpless, surface liquid transport, a necessity if such ceramics are to play an integral role as components of sealed, phase‐change, wickless thermal‐management devices (e.g., vapor chambers or heat pipes) that require rapid working‐fluid transport in their multi‐phase interior. The novelty of this work lies in establishing a scalable methodology for utilizing and further enhancing the properties of this non‐oxide ceramic material for phase‐change heat‐transfer hermetic devices, thereby paving the way toward the implementation of this intriguing material in next‐generation heat spreaders. [ABSTRACT FROM AUTHOR]

The blend matrix composed of polyvinyl alcohol and carboxymethylcellulose (PVA/CMC) was prepared via the casting method. SiO2 nanoparticles were added as reinforcement in different amounts (SiO2 = 1, 2, 3, and 4 wt.%). The study utilized FTIR to examine the alterations in composition and the interplay between the blend matrix and the inclusion of SiO2. Also, for the first time, the surface roughness and surface wettability of the PVA/CMC blend matrix were investigated with the addition of SiO2 using measurements of contact angle and surface roughness parameters. The surface roughness and wettability of the blend matrix increased as the SiO2 content increased. In addition, the blend matrix optical features were determined by the UV–visible spectrophotometer. Based on the analysis using Tauc's relation, it was found that the energy bandgap decreases from 5.52 to 5.17 eV (direct transition) and from 4.79 to 4.32 eV (indirect transition) for the PVA/CMC and PVA/CMC/4%SiO2 blend films, respectively. The refractive index increases from 2.009 to about 2.144 for the PVA/CMC and PVA/CMC/4%SiO2 blend films, respectively. Furthermore, optical conductivity and dielectric constants were improved for the PVA/CMC blend film after the addition of SiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

Unidirectional liquid transport (UDLT) has been widely used in various fields as an important process for transferring both mass and energy. However, UDLT driven by a structural gradient has been witnessed for a long time only in wettable liquids. For nonwettable liquids, UDLT can hardly proceed merely by a structural gradient. Herein, we propose an asymmetrically concave structured surface (AMC-surface), featuring tip-to-base periodically arranged pyramid-shaped concave structures with a certain degree of overlap, which enables the UDLT of both wettable and nonwettable liquids. For wettable liquids, the capillary force along each corner leads to the UDLT pointing toward the base side of the concave pyramid, while for nonwettable liquids, the UDLT is attributable to the static liquid pressure overwhelming the repulsive Laplace pressure induced by the asymmetric grooves and overlapping part. As a result, both wettable and nonwettable liquids transport spontaneously and unidirectionally on the AMC-surface with no energy input. Moreover, the concave structure endows good mechanical stability and can be easily prepared using a facile nail-punching approach over a large area. We also demonstrated its application in a continuous chemical reaction in a confined area. We envision that the unique UDLT behavior on the as-developed AMC-surface will shed new light on the programmable manipulation of various liquids. [ABSTRACT FROM AUTHOR]

This study intended to develop nano Cu-doped nano ZnO-modified ceramic glazes. In this scope, nano-sized ZnO and nano Cu powders were incorporated into a commercial glaze composition and then the modified glaze was applied to the surface using the spraying method. The glazed tiles were sintered in a laboratory furnace at 1210oC for 10 min. The surfaces of the sintered samples were analyzed using scanning electron microscopy. X-Ray diffractometer, surface profilometer and contact angle goniometer. The study examined the influence of varying levels of Cu doping on the microstructural evolution and formation of phases, surface roughness, as well as the contact angle. Additionally, wettability conversion experiments were conducted under UV light. As a result, the addition of Cu increased the presence of Willemite crystals and also increasing the quantity and size of Plagioclase crystals. The contact angle of the sintered commercial glaze coated surface was measured to be 51.8o. However, when nano ZnO was added, the contact angle reduced to 44.4o. Likewise, the contact angle of the Cu doped nano ZnO coated surfaces decreased even further to approximately 33o. The inclusion of nano ZnO in commercial glaze resulted in a decrease in the Ra value, while doping Cu led to a modest increase in the Ra value. UV irradiation resulted in a reduction in the contact angles of all surfaces. [ABSTRACT FROM AUTHOR]

The environmental destruction caused by oil pollution has been an inescapable fact, and there is an urgent need for efficient separation materials to solve this problem. Generally speaking, Polyethylene terephthalate (PET) is relatively easy to modify into super-hydrophobic/super-oleophilic membranes due to its hydrophobic ester groups. However, there are some challenges in preparing them as underwater super-oleophobic films. Herein, this paper proposes a two-step coating method for the preparation of underwater super-oleophobic PET films by coating the surface of PET films with silicone to form a cross-linked layer through polymerization (Cross-linking), followed by coating the surface of the cross-linked layer with a fluorinated compound/SiO2 (Coating-F@SiO2). Experiments have shown that the new filter membrane exhibits excellent corrosion resistance and special wettability (> 150°). After 30 filtration cycles, it still maintains excellent oil–water separation efficiency (> 99.9%). This simple method for preparing oil–water separation membrane enriches the treatment process of oil pollution. The large-area and low-cost preparation route also provides a prospect for scalable applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Realizing an electrode that can stably monitor biosignals after multiple exposures to sweat is challenging. Utilizing a Janus electrode, which is composed of a stack of ultrathin hydrophobic microporous Au membrane and water-durable hydrophilic nanofiber layers, asymmetric wettability can be realized and maintained for 7 days. Thus, it can create spontaneous unidirectional sweat transport from the skin surface, ensuring that the skin-electrode interface remains dry, especially during sweating. The ultrathin hydrophobic membrane facilitates self-adhesion with an adhesion energy of 59.2 µJ cm−2, which creates a high conformal contact to the skin and self-adhering to the hydrophilic nanofibers. The hydrophilic nanofibers exhibit excellent durability even after continuous immersion in water for up to 1 month. Additionally, a thin translucent polyvinyl alcohol nanofibers frame assists the Janus electrode in achieving highly conformable attachment to both dry and sweaty skin. The Janus electrode also exhibits excellent breathability and high mechanical stability owing to its porous structure and fine thickness. With these properties, the Janus electrode can monitor an electrocardiogram signal after dynamic activities, including physical exercise, waking up, desk work, meals, and going out for 6 days, while maintaining a stable signal-to-noise ratio of ∼ 18.8 dB. [ABSTRACT FROM AUTHOR]

The underground storage of CO2 in a depleted carbonate formation is a suitable method for limiting its anthropogenic release and minimize global warming. The rock wettability is an essential factor controlling the mechanisms of CO2 trapping and its containment safety in the geo-storage formation. The geo-storage rock contains innate organic acids which alters the wettability of the rock surface from the hydrophilic condition to the hydrophobic state, thus reduce the CO2 storage capacity. In this study, methyl orange which is a toxic dye that is generally released into environment was used as wettability modifier to change the wettability of stearic acid aged calcite (oil wet) to water wet. This study uses the contact angle technique (sessile drop method) to examine the effects of various concentration of methyl orange (10-100 mg/L) on the wettability of the CO2/brine/stearic-acid aged calcite system under geo-storage conditions (i.e., temperatures of 25 and 50 °C and pressures of 5-20 MPa). The results indicate that the advancing and receding contact angles (qa and qr) of the organic-acid contaminated rock surface were drastically reduced upon exposure to methyl orange, attaining the minimum values of 62°C and 58°C respectively, in the presence of 100 mg/L methyl orange at 20 MPa and 50 °C. Thus, the present results suggest that rather than discharging methyl orange into the environment, it could be injected into underground reservoirs in order to reduce the level of environmental pollution and at the same time increase the CO2 storage capacity of carbonate formations. [ABSTRACT FROM AUTHOR]

Today a lot of attention is paid to the formation of thermosensitive systems for biomedical and industrial applications. The development of new methods for synthesis of such systems is a dynamically developing direction in chemistry and materials science. In this regard, this paper presents results of the studies of a new synthesized supramolecular polymer system based on polyethylene glycol and tetrafluoroethylene telomers. The films formed from the polymer substance have the property of switching wettability depending on temperature after heating activation. It has been established that the wettability changes at 60 °C. The contact angle of activated hydrophobic polymer film reaches 143°. Additionally, the system exhibits its properties regardless of the pH of the environment. Based on data obtained by the methods of infrared and x-ray photoelectron spectroscopy, differential thermal analysis and thermal analysis in conjunction with wettability and morphology, a model of the behavior of molecules in a polymer system was built that ensures switching of the hydrophilic/hydrophobic surface state. The resulting polymer system, as well as films based on it, can be used in targeted drug delivery, implantation surgery, as sensors, etc. [ABSTRACT FROM AUTHOR]

The rapid development of nanotechnology has offered the possibility of creating nanosystems that can be used as drug carriers. The use of such carriers offers real opportunities for the development of non-invasive drug delivery through skin structures. However, in addition to the ability to create suitable nanocarriers, it is also necessary to know how they move through dermal layers. The human skin consists of layers with different wettability characteristics, which greatly complicates how introduced substances move through it. In this work, an experimental study of the diffusion process of nanoparticles through partitions with different wettability properties was carried out. Conventional diffusion tests using Franz chambers were used for this purpose. We quantified how the wettability of the barrier, the number of layers, and their mutual configuration affect the transport of nanoparticles. Based on the results, an analysis of the phenomena taking place, depending on the wettability of the partition, was carried out. A model relationship was also proposed to determine the effective diffusion coefficient, taking into account the influence of the wettability and porosity of the barrier. [ABSTRACT FROM AUTHOR]

Polysaccharide-based systems have very good emulsifying and stabilizing properties, and starch plays a leading role. Their modifications should add new quality features to the product to such an extent that preserves the structure-forming properties of native starch. The aim of this manuscript was to examine the physicochemical characteristics of the combinations of starch with phospholipids or lysozymes and determine the effect of starch modification (surface hydrophobization or biological additives) and preparation temperature (before and after gelatinization). Changes in electrokinetic potential (zeta), effective diameter, and size distribution as a function of time were analyzed using the dynamic light scattering and microelectrophoresis techniques. The wettability of starch-coated glass plates before and after modification was checked by the advancing and receding contact angle measurements, as well as the angle hysteresis, using the settle drop method as a complement to profilometry and FTIR. It can be generalized that starch dispersions are more stable than analogous n-alkane/starch emulsions at room and physiological temperatures. On the other hand, the contact angle hysteresis values usually decrease with temperature increase, pointing to a more homogeneous surface, and the hydrophobization effect decreases vs. the thickness of the substrate. Surface hydrophobization of starch carried out using an n-alkane film does not change its bulk properties and leads to improvement of its mechanical and functional properties. The obtained specific starch-based hybrid systems, characterized in detail by switchable wettability, give the possibility to determine the energetic state of the starch surface and understand the strength and specificity of interactions with substances of different polarities in biological processes and their applicability for multidirectional use. [ABSTRACT FROM AUTHOR]

Multiscale nano/micro-structured surfaces with superhydrophobicity are abundantly observed in nature such as lotus leaves, rose petals and butterfly wings, where microstructures typically reinforce mechanical stability, while nanostructures predominantly govern wettability. To emulate such hierarchical structures in nature, various methods have been widely applied in the past few decades to the manufacture of multiscale structures which can be applied to functionalities ranging from anti-icing and water–oil separation to self-cleaning. In this review, we highlight recent advances in nano/micro-structured superhydrophobic surfaces, with particular focus on non-metallic materials as they are widely used in daily life due to their lightweight, abrasion resistance and ease of processing properties. This review is organized into three sections. First, fabrication methods of multiscale hierarchical structures are introduced with their strengths and weaknesses. Second, four main application areas of anti-icing, water–oil separation, anti-fog and self-cleaning are overviewed by assessing how and why multiscale structures need to be incorporated to carry out their performances. Finally, future directions and challenges for nano/micro-structured surfaces are presented. [ABSTRACT FROM AUTHOR]

This work contributes to the understanding of an interplay between surface chemistry, morphology, and wettability properties, crucial for advancing biomaterial coatings in drug delivery systems. The surface properties of multilevel scaffolds, including a titanium frame, a calcium phosphate (CaP) coating and a poly(lactide-co-glycolide) (PLGA) layer are studied. It is shown that CaP coatings have complex internal morphologies with branched pore structures and spheroidal surface elements. A 5 wt.% PLGA modification, however, does not alter the structure, increasing the PLGA concentration to 8−10 wt.%, leading to the formation of a homogeneous polymer film, changing the porous structure and reducing the surface roughness. The FTIR spectra confirm the presence of various functional groups, correlating with changes in properties. A systematic analysis of the hydrophilic/hydrophobic nature, free surface energy, and surface roughness of pure CaP and pure PLGA surfaces as well as CaP/PLGA samples is given. The pure CaP coating and pure PLGA are found to be hydrophilic, with the water contact angles lower than 26° and 74°, respectively. An application of PLGA to the CaP coatings resulted in hydrophobization, with the water contact angles exceeding 94°. [ABSTRACT FROM AUTHOR]

In this work, the spreading of a small sessile drop on a smooth, flat surface has been analyzed. A comprehensive energy balance was developed that consists of wetting energy, air-liquid interfacial energy, gravitational energy, and heat due to flow dissipation. The net change in these energies is predicted to vary widely with the wettability of the solid surface. On the least wettable surfaces, energy released by contraction of the air-liquid interface drives spreading. On the most wettable surfaces, spreading is powered by wetting energy released from the advancing contact line. On surfaces with intermediate wettability, spreading is fueled by a combination of energies released from both the air-liquid interface and the contact line. Generally, gravitational energy is minuscule compared to the other energies. Overall, the model suggests that spreading is exothermic, as expected for a spontaneous process. Small liquid drops with a wide variety of surface tension and density are anticipated to give similar results. [ABSTRACT FROM AUTHOR]

Biomolecular coacervates are emerging models to understand biological systems and important building blocks for designer applications. DNA can be used to build up programmable coacervates, but often the processes and building blocks to make those are only available to specialists. Here, we report a simple approach for the formation of dynamic, multivalency-driven coacervates using long single-stranded DNA homopolymer in combination with a series of palindromic binders to serve as a synthetic coacervate droplet. We reveal details on how the length and sequence of the multivalent binders influence coacervate formation, how to introduce switching and autonomous behavior in reaction circuits, as well as how to engineer wetting, engulfment and fusion in multi-coacervate system. Our simple-to-use model DNA coacervates enhance the understanding of coacervate dynamics, fusion, phase transition mechanisms, and wetting behavior between coacervates, forming a solid foundation for the development of innovative synthetic and programmable coacervates for fundamental studies and applications. Biomolecular coacervates are emerging model systems to understand biological processes. Here, the authors reveal details on how the length and sequence of the DNA binders influence the multivalency-driven coacervate formation, how to introduce switching and autonomous behavior in reaction circuits, as well as how to engineer wetting, engulfment, and fusion in multi-coacervate system. [ABSTRACT FROM AUTHOR]

Nowadays, there has been a recognition of the remarkable potential of nanofluids and microorganisms as eco-friendly agents for enhanced oil recovery. on the other hand, one of the unique strategies for boosting hydrocarbon recovery is altering the wettability of the rock surface of oil and gas reservoirs. Herein, a nanohybrid that combines graphene oxide (GO) and silica (SiO2) was synthesized using a low-temperature, facile, and eco-friendly approach (sol-gel). GO-SiO2 nanocomposite was characterized with the aid of XRD, SEM, and FTIR analyses. Afterward, Nanofluids with different concentrations (0.005, 0.01, 0.015, and 0.02 wt%) of GO-SiO2 nanocomposite at various ratios (1:1, 1:2, and 2:1) were prepared using a surfactant-free and pH-neutral approach with a salinity of 30,000 ppm. The results of the Zeta potential measurement reveal that the manufactured nanofluids have great stability and the ratio of 1:1 was the most effective ratio for improving the reservoir wettability change from oil-wet to water-wet. At a higher temperature of 80 °C compared to the ambient condition of 25 °C, a more significant change in wettability was observed (23° to 161°). At the optimal concentration of nanofluid (0.015 wt%), the contact angle increased from 23° (on a non-treated surface) to 161°. These findings suggest that GO-SiO2 has great potential as an affordable, flexible, and environmentally friendly natural nanofluid, particularly under harsh conditions for the EOR process. [ABSTRACT FROM AUTHOR]

Enhancing oil recovery through surfactants has proven to be a successful strategy in recent times. However, traditional surfactants have their limitations, particularly in terms of stability under high temperatures and salinity levels. This study delved into a groundbreaking macromolecular polymeric surfactant, S‐AV, which holds the unique ability to transform rock surface characteristics, effectively stripping away residual oil while maintaining resilience against elevated temperatures and salinity. S‐AV was synthesized through a free‐radical copolymerization process, incorporating benzyl, perfluoroalkyl, alkyl‐, benzyl‐, ethylene glycol, and amide‐alkyl‐sulfonate groups, ultimately yielding a comb‐like molecular structure. S‐AV demonstrated exceptional prowess, swiftly reducing the underwater oil contact angle to 53.4° in just 48 h. This synthesized surfactant also retained its phase stability up to salinity levels of 36,000 ppm, with temperature having no disruptive impact on its phase stability performance. Furthermore, S‐AV showcased remarkable viscosity reduction in conditions of high temperature and salinity. The core flooding experiments underscored the potential of S‐AV, as its injection led to a significant oil recovery rate of up to 83%. These findings position S‐AV as a promising candidate for practical enhanced oil recovery applications. [ABSTRACT FROM AUTHOR]

This study investigates the adsorption behaviors of surfactants in sandstone reservoir rocks containing various amounts of carbonate cement/minerals and their impact on wettability alteration under low‐salinity conditions. Two types of rock samples from sandstone reservoirs of Assam oilfields in India are selected based on XRD results. These rock types are (i) high carbonate cement (HCC) core sample with higher carbonate cement (calcite 5.6% and dolomite 4.0%), and (ii) low carbonate cement (LCC) core sample with lower carbonate cement (calcite = 0.5% and dolomite 0%). The study reveals that the mineralogy of sandstone reservoir rocks especially the carbonate minerals affects the brine‐rock interactions including wettability alternation and surfactant adsorption. Notable differences (2° to 8°) in contact angles for the two rock types at different salinities revealed that carbonate cement in sandstone thus impacts brine‐rock interactions. Further, low salinity surfactant (LSS) could positively alter the wettability of both rock types to water‐wet conditions (contact angle <60°). The most favorable wettability alterations (up to 30°) were achieved with cationic LSS solutions for both core types. Using LSS solutions also reduced the adsorption of anionic surfactant by around 40% and 33% for HCC and LCC rock samples, respectively. The study's novelty emanates from investigating the impact of sandstone reservoir rock mineralogy with varying amounts of carbonate cements on the adsorption behavior of surfactants under low‐salinity conditions. Moreover, this study provides a better understanding of the interrelationship existing between the degree of wettability alteration and the amount of surfactant adsorbed by sandstone rocks. [ABSTRACT FROM AUTHOR]

Usage of cost effective synthesis methods are inevitable due to increasing economic conditions worldwide. In this study, zinc oxide nano-structures were synthesized by low cost chemical methods. Outcomes of X-ray diffraction analysis revealed dominating plane was c-axis for ZnO seed layer and nano-rods deposited by sol–gel spin coating and chemical bath deposition method (CBD), respectively. However, a-axis plane dominance was observed for ZnO nano-rods prepared by hydrothermal method. Scanning electron microscopy offered the surface morphology of granular structure and well aligned compact ZnO nano-rods by sol–gel and CBD, respectively. Conversely, randomly oriented ZnO nano-rods were found by hydrothermal method. Presence of zinc and oxygen in the samples was confirmed by EDS results. Optical band gap of 3.29 eV, 3.25 eV and 3.21 eV were obtained by sol–gel, CBD and hydrothermal method, respectively. Likewise, photoluminescence results were also analyzed for all the samples. The super-hydrophobic state with water contact angle (WCA) of 150° was observed for ZnO nano-rods by CBD. However, hydrophilic and hydrophobic state was detected for ZnO seed layer and nano-rods with WCA of 70° and 118°, respectively. The super-hydrophilic state was also noticed after the induction of Ultra-Violet (UV) light. The WCA reduction rate of the values 0.067 and 0.17 were estimated for ZnO nano-rods. Furthermore, CA recovery time was also measured. The UV sensing photo-response was evaluated among seed layer and nano-rods, and better result was produced by ZnO nano-rods by CBD. [ABSTRACT FROM AUTHOR]

In the current work, the chemical etching process and hydrothermal method were used to create bio‐inspired superhydrophobic fluorine‐free tin oxide nanostructures on copper plates. Taguchi's experimental design was also used in investigating coating wettability characteristics based on fabrication parameters. Statistical analysis results demonstrated that the optimal superhydrophobic sample with a water contact angle of 163.40° ± 1.42° and contact angle hysteresis of 3.00° ± 0.80° could be fabricated under the following conditions: sodium hydroxide (2.00 M) as an etching solution, urea‐to‐tin chloride ratio 2.5:1, and 2.00 h reaction times. The effects of each synthesis parameter on the obtained sample's superhydrophobicity were evaluated through multiple one‐variable‐at‐a‐time experiments. Testing the chemical stability of the optimal sample revealed that it was more resistant to deterioration in an alkaline environment (8–10) than in an acidic environment (4–6). The resulting superhydrophobic sample was analyzed by a delay test for water droplets freezing on its surface to determine whether ice formed and accumulated. The created bio‐inspired honeycomb‐like nanocoating demonstrated exceptional mechanical robustness and good anti‐icing performance after 10 consecutive icing cycles. These results indicated that superhydrophobic coatings could be easily and economically produced without using fluoropolymers and silanes on aluminum substrates. [ABSTRACT FROM AUTHOR]

This research employed the pseudopotential multi-relaxation times lattice Boltzmann method to investigate the impact process of a droplet on solid surfaces, focusing on the influence of surface wettability for three different Reynolds numbers Re = 100, 200, and 500). Initially, the impact process is studied on both hydrophobic and hydrophilic surfaces, revealing distinct behaviors characterized by spreading and recoiling stages. Subsequently, the investigation extends to a mixed wettability wall, offering insights into the droplet's density behaviors. Through this study, we demonstrate that the wettability of the surface plays a crucial role in determining the contact dynamics with the impacting droplet. Notably, the average velocity of the droplet exhibits a monotonic increase with higher wettability. Furthermore, the droplet profile responds to variations in the Reynolds number, though droplet deformation remains relatively limited even when the interaction with the wetting surface intensifies. Our findings shed light on the complex interplay between wettability, droplet dynamics, and surface interactions during impact processes. • The Pseudopotential multi-relaxation times lattice Boltzmann method to analyze the impact of droplets on surfaces is used. • The process of spreading droplets on hydrophobic and hydrophilic surfaces and a mixed wettability surface is investigated. • The behavior of the droplet with Reynolds number on the wetting surface is studied. [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]