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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]

[Display omitted] Electrowetting on conventional dielectrics requires direct fluid-electrode contact to generate strong electric fields at the three-phase contact line to modulate the wetting. Since the electric field alters wetting, the modulation of wetting can be achieved by applying an external electric field through insulated electrodes, preventing the liquid from contacting the electrodes. A simple and efficient method for non-contact between the fluid and the electrode external electric field modulation of fluid wetting was proposed. The switching ability of droplets on microgroove surfaces from Cassie-Baxter to Wenzel wetting state under an external electric field was used to drive and quantify the relationship between wetting, contact angle, and the applied voltage. Applying an external electric field modulates the wetting of deionized water, ionic liquids, and high-viscosity liquids on microgrooves. The wetting degree of liquid can be controlled by adjusting the external voltage parameters. The finite element simulations revealed that the Maxwell force drove this process. The effects of substrate size and liquid properties on wetting behavior were also examined. Post-application cross-sectional imaging showed the formation of a conformal interface, highlighting the relevance of the proposed method in advanced adaptive shape fabrication and microfluidic control, among other applications. [ABSTRACT FROM AUTHOR]

To further improve the basic theory of blast furnace hydrogen-rich smelting and provide a reference for blast furnace hydrogen-rich production, the influences of different conditions on the contact angle and carburization amount of the iron‒coke interface were measured using iron‒coke interface reaction experiments, and the erosion of the three-dimensional morphology of the coke surface by the iron‒coke interface reaction process was analysed. As the degree of coke dissolution increased, the iron‒coke interface contact angle increased, and the amount of carburization decreased. The change in the interface contact angle and carburization amount between iron and coke after reacting with H 2 O was greater than that after reacting with CO 2 , and the interface reaction rate constant and carburization amount were lower for H 2 O than CO 2. When the reaction time increased by 1 min, the differences in the contact angle and carburization amount between the two atmospheres increased by 0.12° and 0.013%, respectively. This improved the permeability of the metal iron for its penetration in the coke layer and was beneficial for stable production. An increase in the reaction temperature and a decrease in the initial carbon mass fraction (w (C)) of metallic iron both increased the carburization rate at the iron‒coke interface, reduced the equilibrium contact angle, improved wettability, and caused severe erosion of the carbon matrix structure on the coke surface. When the temperature exceeded 1673 K, the metal iron could undergo a violent carburization process with coke surface 3, resulting in a wetting phenomenon. The initial w (C) of metallic iron increased by 1%, and the equilibrium contact angle of the iron‒coke interface increased by approximately 3.32°. [Display omitted] • Analyse the interface behavior between iron and coke after reacting with H 2 O and CO 2. • The surface of coke after reacting with H 2 O has poorer wettability with iron. • The effect of various factors on iron-coke wettability was quantitatively analysed. [ABSTRACT FROM AUTHOR]

Due to the considerable uncertainties inherent in the datasets describing the spatiotemporal distributions of precipitation in the drylands of China, this study presents a new merged monthly precipitation product with a spatial resolution of approximately 0.2° × 0.2° during 1980–2019. The newly developed precipitation product was validated at different temporal scales (e.g., monthly, seasonally, and annually). The results show that the new product consistently aligns with the spatiotemporal distributions reported by the Chinese Meteorological Administration Land Data Assimilation System (CLDAS) product and Multi-Source Weighted Ensemble Precipitation (MSWEP). The merged product exhibits exceptional quality in describing the drylands of China, with a bias of −2.19 mm month−1 relative to MSWEP. In addition, the annual trend of the merged product (0.09 mm month−1 yr−1) also closely aligns with that of the MSWEP (0.11 mm month−1 yr−1) during 1980–2019. The increasing trend indicates that the water cycle and wetting process intensified in the drylands of China during this period. In particular, there was an increase in wetting during the period from 2001–2019. Generally, the merged product exhibits potential value for improving our understanding of the climate and water cycle in the drylands of China. [ABSTRACT FROM AUTHOR]

An experimental apparatus was designed to study the impacts of wettability on evaporation of water from Ottawa sand. Evaporation rates were measured for: (1) a 5.7-cm-thick layer of hydrophilic Ottawa sand; (2) a 5.7-cm-thick layer with 12% hydrophobic content, consisting of a 0.7-cm-layer of n-Octyltriethoxysilane-coated hydrophobic sand buried 1.8 cm below the surface of hydrophilic sand; and (3) a 5.7-cm-thick layer with mixed wettabilities, consisting of 12% n-Octyltriethoxysilane-coated hydrophobic sand mixed into hydrophilic sand. The sand-water mixtures experienced forced convection above and through the sand layer, while a simulated solar flux (i.e., 112±20 W/m²) was applied. Evaporation from homogeneous porous media is classified into the constant-rate, falling-rate, and slow-rate periods. Wettability affected the observed evaporation mechanisms, including the transition from constant-rate to falling-rate periods. Evaporation entered the falling-rate period at 12%, 20%, and 24% saturations for the all hydrophilic sand, hydrophobic layer, and hydrophobic mixture, respectively. Wettability affected the duration of the experiments, as the all hydrophilic sand, hydrophobic layer, and hydrophobic mixture lasted 17, 20, and 26 trials, respectively. Both experiments with hydrophobic particles lasted longer than the all hydrophilic experiment and had shorter constant-rate evaporation periods, suggesting hydrophobic material interrupts capillary action of water to the soil surface and reduces evaporation. Sand temperatures suggest more evaporation occurred near the test section inlet for higher saturations and the hydrophobic layer experienced more evaporation occur near the outlet. Evaporation fluxes were up to 12× higher than the vapor diffusion flux due to enhanced vapor diffusion and forced convection. [ABSTRACT FROM AUTHOR]

Intrinsic wetting behaviors of Ag, AgCu and AgCuTi on TC4 were studied by ISD and MSD method. A linear spreading was found in Ag/TC4 system with a rate of ~ 0.14 mm/s. No significant difference in wetting behavior between AgCu/TC4 and AgCuTi/TC4, which can be divided into three stages. The first stage is controlled by the dissolution process at the solid/liquid interface, and the second and third stages are characterized by near linear and linear spreading. The corresponding spreading rates are ~ 0.017 mm/s and ~ 0.004 mm/s, which may be controlled by the solid solution reactions of Cu and TC4 and Ag and TC4, respectively. [ABSTRACT FROM AUTHOR]

The wetting behavior of molten Cu on the B4C-xTiB2 ceramic composites was investigated in this work. The results show that the contact angle of molten Cu alloy on B4C-TiB2 ceramic composites is linear with the composition rate of TiB2 or B4C while the temperature is in the range of 1 300 to 1 350 °C, consistent with the expectation of the commonly used theoretical method. However, a nonlinear relationship between the contact angle and the composition rate unexpectedly occurred at temperatures ranging from 1 400 to 1 500 °C. The big difference of the contact angles between the molten metal and the components in the composites was found to be the key point. This result identifies that the commonly used theoretical method only works at a limited difference of the contact angle of the liquid on the different phases in the composites, and fails at a big difference. [ABSTRACT FROM AUTHOR]

The self-driven behavior of droplets on a functionalized surface, coupled with wetting gradient and wedge patterns, is systematically investigated using molecular dynamics (MD) simulations. The effects of key factors, including wedge angle, wettability, and wetting gradient, on the droplet self-driving effect is revealed from the nanoscale. Results indicate that the maximum velocity of droplets on hydrophobic wedge-shaped surfaces increases with the wedge angle, accompanied by a rapid attenuation of driving force; however, the average velocity decreases with the increased wedge angle. Conversely, droplet movement on hydrophilic wedge-shaped surfaces follows the opposite trend, particularly in terms of average velocity compared to the hydrophobic case. Both wedge-shaped and composite gradient wedge-shaped surfaces are found to induce droplet motion, with droplets exhibiting higher speeds and distances on hydrophobic surfaces compared to hydrophilic surfaces, regardless of surface type. Importantly, the inclusion of wettability gradients significantly influences droplet motion, with hydrophobic composite gradient wedge-shaped surfaces showing considerable improvements in droplet speed and distance compared to their hydrophilic counterparts. By combining suitable wettability gradients with wedge-shaped surfaces, the limitations inherent in the wettability gradient range and wedge-shaped configuration can be mitigated, thereby enhancing droplet speed and distance. The findings presented in this paper offer valuable insights for the design of advanced functional surfaces tailored for manipulating droplets in real-world applications. [ABSTRACT FROM AUTHOR]

To investigate the microscopic mechanism underlying the influence of surface-chemical gradient on heat and mass recovery, a molecular dynamics model including droplet condensation and transport process has been developed to examine heat and mass recovery performance. This work aimed at identify optimal conditions for enhancing heat and mass recovery through the combination of wettability gradient and nanopore transport. For comprehensive analysis, the structure in the simulation was categorized into three distinct groups: a homogeneous structure, a small wettability gradient, and a large wettability gradient. The homogeneous surface demonstrated low efficiency in heat and mass transfer, as evidenced by filmwise condensation. In contrast, the surface with a small wettability gradient experienced a transition from dropwise condensation to filmwise condensation, resulting in a gradual decrease in the efficiency of vapor heat and mass transfer. Only a large wettability gradient could achieve periodic and efficient dropwise condensation heat and mass transfer which was attributed to the rapid droplet coalescence and transport to the nanopore after condensing on the cold surface. [ABSTRACT FROM AUTHOR]

Lifting individual water droplets against gravity without external energy input is reported. Classical capillary rise requires the complete wetting of a transport pathway, resulting in water loss and poor collection efficiency. Boosting Laplace pressure propulsion while diminishing contact line pinning enables lossless water droplet ascension. Surfaces with properly designed physicochemical gradients can propel single water droplets as high as 65 mm against gravity, enabled by 1) surface wettability patterns, 2) liquid‐like polymer brushes, and 3) controlling droplet size within a shorebird beak‐inspired wedge geometry. Surface wettability patterns induce droplet elongation toward the gap‐to‐apex direction of the wedge geometry, which boosts Laplace pressure propulsion by increasing droplet length and diminishes contact line pinning by decreasing droplet width. Polymer brushes for wettability patterning exhibit minimal contact angle hysteresis, minimizing contact line pinning and enabling residue‐free droplet ascension. Controlling the droplet size prevents the dominance of either contact line pinning or gravity over Laplace pressure propulsion, enabling droplet transport against gravity. Utilizing these design rules, low surface tension n‐decane is also transported against gravity, and a particle‐laden solution is separated using sedimentation and against‐gravity transportation. Such surfaces may facilitate lossless, against‐gravity, and power‐free water pumps in numerous emerging sustainability and energy applications. [ABSTRACT FROM AUTHOR]

Background: The SeDeM-ODT expert system is designed to assess the suitability of the pharmaceutical ingredients for their conversion into an orodispersible formulation by direct compression. The tool can be utilized to select the most appropriate excipients that improve the compressibility and buccodispersibility of the formulation. Objective: This study aimed to utilize the SeDeM-ODT expert system to evaluate the performance of superdisintegrants and select an appropriate superdisntegrant for Doxylamine Succinate orodispersible formulation. Method: The SeDeM-ODT expert system scrutinized the excipients to develop an orodispersible Doxylamine Succinate formulation. Among the 15 parameters of the tool, some of them were determined through experimental work, while the remaining were calculated through the experimental values of other parameters. The central composite design approach was used for formulation development. The prepared powder blends were compressed using the direct compression method and evaluated for different parameters (hardness, thickness, diameter, friability, weight variation, water absorption ratio, wetting time, and disintegration time). Results: The results of the SeDeM-ODT expert system were correlated with the values obtained by the post-compression tests. The Crospovidone formulation (F7) was found to be an optimized formulation as it disintegrated quickly compared with the other formulations containing other superdisintegtrants. The results perfectly endorsed the SeDeM-ODT expert system evaluation, as Crospovidone showed the highest IGCB value of 6.396. Conclusion: The study observed the effectiveness of the expert system in accurately examining the performance of disintegrating agents. The study observed the effectiveness of the expert system in accurately examining the performance of disintegrating agents. The assessment proved Crospovidone to produce quicker disintegration in Doxylamine Succinate orodispersible formulation. [ABSTRACT FROM AUTHOR]

This study investigated the synthesis mechanism of tantalum boride (TaB2) powder via the boron/carbothermal reduction method, based on thermodynamic calculations and experimental results. The insufficient presence of the intermediate product B2O3 leads to the emergence of TaC and Ta3B4, while in the presence of a sufficient boron source in the reaction system, the primary products formed include TaB2, TaC, and B2O3, with TaC subsequently reacting with B2O3 and carbon to yield TaB2. TaB2 powder was successfully synthesized at 1500°C with the addition of an excess of 20 wt% B4C. The particle size of the powder was approximately 298 nm, and the oxygen content and carbon content in the powder were 0.6 and 0.1 wt.%, respectively. [ABSTRACT FROM AUTHOR]

A large volume of water is bypassing oil and comes up without being able to push it out from the reservoir after organic material adsorption. This work investigates hydrophobicity effect on rock wettability, oil recovery, and relative permeability. The μXRF was used to characterize sand cores, and a contact angle goniometer to determine fluids contact angle. Oil recovery was evaluated by measuring the incremental oil volume recovered in a glass and PVC capillary designed micromodel. Relative permeability was studied using the steady state method, and the wettability was determined by the Amott method. The results show that cores are mainly composed of quartz 86.04%. Oil recovery was 30.50% for oil-wet state; where the wettability index was −0.283. Thereafter, it has been demonstrated that the surfactant solution increases the oil recovery with 23.54 ℅. Adsorption of surfactants on functional groups of PVC change the contact angle between water and PVC's surface from 112° to 39°, decrease the IFT and restore the water-wet state. PVC debris presents efficient new method to determine the water by pass effect on oil recovery. The findings of this study help for better understanding the surfactant-oil displacements during water flooding in light oil reservoirs with impaired wettability. [ABSTRACT FROM AUTHOR]

[Display omitted] Superhydrophobic surfaces can effectively prevent the freezing of supercooled droplets in technological systems. Droplets on superhydrophobic surfaces commonly not only wet the top asperities (Cassie State), but also partially penetrate into microstructure due to surface properties, environment, and droplet impact occurring in real-world applications. Implications on ice nucleation can be expected and are little explored. It remains elusive how anti-icing surfaces can be designed to exploit intermediate wetting phenomena. We utilized engineered micro-/nanostructures, specifically micropillars, to modulate the wetting fraction in the microstructure. The behavior of intermediate wetting with supercooling and resulting implications on ice nucleation delay when potential nucleation sites are formed in the microcavities were investigated using experimental, theoretical, and simulation components. The temperature-dependent wetting fraction in the microstructure increased at supercooled temperatures, partly activated by condensation in the microcavities. At −10/−20 °C, a critical wetting fraction led to maximum ice nucleation delays, with experimental results consistent with theoretical predictions. This critical wetting fraction minimized the effective contact area solid-to-liquid along the partially wetted microstructure. The study establishes physical relations between ice nucleation delays, geometrical surface parameters and wettability properties in the intermediate wetting regime, providing guidance for the design of ice resistant microstructured surfaces. [ABSTRACT FROM AUTHOR]

[Display omitted] To understand the complex interplay of topography and surface chemistry in wetting, fundamental studies investigating both parameters are needed. Due to the sensitivity of wetting to miniscule changes in one of the parameters it is imperative to precisely control the experimental approach. A profound understanding of their influence on wetting facilitates a tailored design of surfaces with unique functionality. We present a multi-step study: The influence of surface chemistry is analyzed by determining the adsorption of volatile carbonous species (A) and by sputter deposition of metallic copper and copper oxides on flat copper substrates (B). A precise surface topography is created by laser processing. Isotropic topography is created by ps laser processing (C), and hierarchical anisotropic line patterns are produced by direct laser interference patterning (DLIP) with different pulse durations (D). Our results reveal that the long-term wetting response of polished copper surfaces stabilizes with time despite ongoing accumulation of hydrocarbons and is dominated by this adsorption layer over the oxide state of the substrate (Cu, CuO, Cu 2 O). The surfaces' wetting response can be precisely tuned by tailoring the topography via laser processing. The sub-pattern morphology of primary line-like patterns showed great impact on the static contact angle, wetting anisotropy, and water adhesion. An increased roughness inside the pattern valleys combined with a minor roughness on pattern peaks favors air-inclusions, isotropic hydrophobicity, and low water adhesion. Increasing depth of the primary topography can also induce air-inclusions despite increasing peak roughness while time dependent wetting transitions were observed. [ABSTRACT FROM AUTHOR]

ABSTRACT Considering the rapid liquid transport characteristics of bionic dragonfly wings, an experimental investigation into the stability and drag reduction properties of an air film on various textured surfaces is being conducted. The study examines the impact of different wetting gradient textures on the stability and drag reduction properties of air film. Experimental results demonstrate an enhanced fluid transport efficiency, resulting in a maximum drag reduction of 9.1%, attributed to the size effect of the multi‐scale structure of bionic dragonfly wings. Surfaces featuring wetting gradients exhibit increased stability of the air film within the texture and the ability to trap air bubbles. Based on a near‐wall flow two‐phase flow theory model, the simulation considers the morphological changes of the air film at structured interfaces and their influence on near‐wall flow characteristics. The results indicate that the drag reduction effect arise from the slippage effect between the internal vortex in the air film inside the texture and the flow field near the wall surface. The synergistic effect of near‐wall flow fields among multiple texture layers is evident. This interplay across different regions contributes to the sustained drag reduction within the near wall area. [ABSTRACT FROM AUTHOR]

Hydrophobized soils have functional hydrophobic coatings to delay or restrict water infiltration and thus prevent infrastructure failure and long-term degradation. Over time, hydrophobized soils will be subjected to degradation under the action of external stresses, leading to the loss of its functional properties. Microencapsulation approaches, initially developed for self-healing applications emerge as a potential solution to enhance, switch (from hydrophilic) or prolong the longevity of hydrophobized soils. The aim of this study is to produce and investigate the effectiveness of microencapsulation to impart hydrophobicity in granular materials in response to external stimuli. In this research, polydimethylsiloxane (PDMS), with hydrophobic properties, is encapsulated in calcium alginate microcapsules with the ionic gelation method. The effectiveness of the microcapsules to induce hydrophobicity is investigated by mixing sand with microcapsules and quantifying the change of the contact angle and water drop penetration time (measures of hydrophobicity) under an external trigger, i.e., under drying and consecutive wetting–drying cycles. The results show that microcapsules release the hydrophobic cargo (PDMS) during shrinkage. After drying, the PDMS content in sand increased to 0.1–0.8% by mass of sand. The released hydrophobic cargo (PDMS) induced hydrophobicity in sands, reflected by a contact angle increase from 29.7° to at least 87.7°. The amount of polydimethylsiloxane encapsulated is a key parameter controlling the release of hydrophobic cargo. In addition, 4% capsule content in sands is identified as an effective microcapsule content in inducing hydrophobicity. [ABSTRACT FROM AUTHOR]

The effect of extreme water repellency, called the lotus effect, is caused by the formation of a Cassie–Baxter state in which only a small portion of the wetting liquid droplet is in contact with the surface. The rest of the bottom of the droplet is in contact with air pockets. Instrumental methods are often used to determine the textural features that cause this effect—scanning electron and atomic force microscopies, profilometry, etc. However, this result provides only an accurate texture model, not the actual information about the part of the surface that is wetted by the liquid. Here, we show a practical method for estimating the surface fraction of texture that has contact with liquid in a Cassie–Baxter wetting state. The method is performed using a set of ethanol–water mixtures to determine the contact angle of the textured and chemically equivalent flat surfaces of AlSI 304 steel, 7500 aluminum, and siloxane elastomer. We showed that the system of Cassie–Baxter equations can be solved graphically by the wetting diagrams introduced in this paper, returning a value for the texture surface fraction in contact with a liquid. We anticipate that the demonstrated method will be useful for a direct evaluation of the ability of textures to repel liquids, particularly superhydrophobic and superoleophobic materials, slippery liquid-infused porous surfaces, etc. [ABSTRACT FROM AUTHOR]

Nanocellulose is among the most promising materials for enhancing the mechanical properties of polymer composites. Broad application is, however, limited by inadequate surface properties. A standard technique for tailoring the surface composition and wettability of polymers is a brief treatment with non-equilibrium gaseous plasma, but it often fails when treating materials with a large surface-to-mass ratio, such as cellulose nanofibers. In this paper, the theoretical limitations are explained, the approaches reported by different groups are reviewed, and the results are interpreted. The treatment of dry nanocellulose is limited by the ability of uniform treatment, whereas the plasma treatment of nanocellulose dispersed in liquids is a slow process. The methods for enhancing the treatment efficiency for both dry and water-dispersed nanocellulose are explained. [ABSTRACT FROM AUTHOR]

Droplet-based microfluidics exhibit numerous benefits leading to relevant innovations and many applications in various fields. The precise handling of droplets in capillaries, including droplet formation, manipulation, and separation, is essential for successful operation. Only a few reports are known concerning the separation of segmented flows, particularly the continuous separation of droplets, which is of high interest regarding the control of biochemical and chemical reactions or other applications where the contact time of the involved phases is crucial. Here, the separation must be flexible and adjusted to different flow parameters, such as the surface tension, the volumetric flow rates, and their ratios. This contribution presents two novel open-source approaches based on additive manufacturing and mechanical deforming for continuous liquid–liquid separation under various flow conditions. The Laplace pressure is the driving force for the separation, which is adjusted to the flow conditions by adapting the distance of pinning points provided by the design of the devices. Details of the device design and experimental setup are shown along with limitations to promote further development and to increase availability for researchers. With the right parameters, sophisticated separations can be realized by inexpensive laboratory equipment and simple control of them. It was found that the distance between the pinning points needs to enlarged for increasing volumetric flow rates and reduced for higher viscosities of the continuous phase respectively higher amounts of the dispersed phase. The open source approach of this article expands the exploration space in addition to commercially available phase separators only available to a selected group of people. [ABSTRACT FROM AUTHOR]

The presented work explores detail information about surface modification of BNNTs with ZrO 2 through isothermal hydrolysis process for reducing its hydrophobic property and enhancing the wettability as BNNTs possess hydrophobicity & poor wettability in its raw form as it agglomerates during fabrication of composites, ultimately prohibits usage of BNNTs as a prime reinforced material and for other utilization. HRTEM, EDX, E.M confirmed thin coating layer of ZrO 2 whereas X-ray diffraction and FE-SEM determined the morphological structure of BNNTs in its raw form comparing with properties of BNNTs@ZrO 2. Contact angle test displays increased wettability of synthesised BNNTs where Zeta Potential provides upgraded stability and dispersibility of coated BNNTs in aqueous medium. Confirmation of coating, improved surface architecture and chemical properties of coated BNNTs than non-treated BNNTs is observed via FTIR. BNNTs@ ZrO 2 showing thermally stable and constant throughout temperature beyond 800 °C through TGA. Present study describes the features of BNNTs and BNNTs@ZrO 2 enriching morphological and thermal characteristics followed by confirmation of coating layer through isothermal hydrolysis process, improvement in wettability and hydrophobicity for further future approach towards reinforcement in MMCs, in a nut shell very effectively applicable in aerospace and automobile industrial utilization. [ABSTRACT FROM AUTHOR]

Acidification is an important factor in the aging of paper literature. Since most of the paper is sized and the surface tension of water is high, it is usually difficult for aqueous phase deacidification agent to penetrate the paper resulting in uneven deacidification. The addition of surfactant can effectively reduce the liquid surface tension and enhance the effect of deacidification with wetting properties improvement. In this paper, polysorbate-80 and polyether-modified trisiloxane surfactants were added to sodium propionate aqueous deacidification agent separately, researching the effect of wettability on the paper literature deacidification by ultrasonic atomization. The results show that SP-TRSE is effective, the maximum enhancement of deacidification agent absorption after adding wetting additives is 238.20 %, the minimum standard deviation of water content and alkali reserve after treatment is 3.87 and 0.005 respectively, the maximum increase in the internal mass fraction of sodium is 0.29 %. [ABSTRACT FROM AUTHOR]

Copyright of Chemical Engineering (China) / Huaxue Gongcheng is the property of Hualu Engineering Science & Technology Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper presents the results of a study of the effect of treatment with nanosecond electromagnetic pulses (NEMPs) on some thermodynamic characteristics of polymers used in the production of reinforced fiberglass plastics. It has been found that NEMP treatment of YD-128 epoxy resin, Polysystem VE-3701 LVP vinyl ester resin, and Polysystem YMI-100 polyester resin has a modifying effect. It is noted that the treatment of thermosetting synthetic resins with NEMPs has a modifying effect, which is expressed in a change in viscosity, surface tension and polarity of the resins under study. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The separation of oil-in-water emulsion is an urgent challenge because its massive production and discharge from daily and industrial activities have caused severe hazards to the ecosystem and serious threats to human health. Membrane technology is considered an outstanding solution strategy for the separation of oil-in-water emulsions due to its unique advantages of low cost, high efficiency, easy operation, and environmental friendliness. However, the membrane is easily fouled by the emulsion oil droplets during the separation process, causing a sharp decline in permeation flux, which greatly inhibits the long-term use of the membrane and largely shortens the membrane's life. Recently, it was found that endowing the membranes with special wettability e.g., superhydrophilic and superoleophobic can greatly enhance the permeability of the continuous water phase and inhibit the adhesion of oil droplets, thus promoting the separation performance and anti-oil-fouling property of membrane for oily emulsions. In this paper, we review and discuss the recent developments in membranes with special wettability for separating oil-in-water emulsions, including the mechanism analysis of emulsion separation membrane, membrane fouling issues, design strategies, and representative studies for enhancing the membrane's anti-oil-fouling ability and emulsion separation performance. [ABSTRACT FROM AUTHOR]

Carbon storage technology is primarily targeted in saline formations, which is a porous rock matrix filled with brine, sealed with a low permeability caprock. There are significant variations of CO2 wetting properties, typically reported in the literature as contact angle of CO2 and brine interacting with a rock material, suggesting that CO2 could become wetting under geostorage conditions and negatively impact containment effectiveness. Here, we performed the first controlled laboratory measurements of CO2‐brine contact angles on shale rocks from low permeability sealing formations with distinctive mineralogic properties—calcite‐rich, quartz‐rich, and dolomite‐rich. We targeted temperatures at 40° and 100°C, pressures at 8.3, 34.5, and 62.1 MPa, and salinity at 35,000 and 260,000 ppm. Results show no significant change in contact angle with mineralogy, temperature, pressure, salinity, and CO2 bubble size. We conclude that caprocks will remain water‐wet at geologic CO2 storage conditions and will not lose their capillary sealing capacity. Plain Language Summary: Carbon capture and storage technology is gaining momentum to reduce carbon dioxide (CO2) emissions to mitigate global warming by capturing the CO2 produced by stationary industrial sources, transporting it, and then storing it deep underground. CO2 storage is primarily targeted in saline formations, which is a porous rock matrix filled with brine, sealed with a low permeability caprock. Several studies have examined the sealing ability of caprocks and suggested that CO2 could become wetting under geostorage conditions and negatively impact containment effectiveness. Our controlled laboratory experiments show caprocks with different mineral compositions will remain water‐wet at geologic CO2 storage conditions and will not lose their capillary sealing ability. Key Points: Performed first CO2‐brine contact angle experiments on shale rocks from sealing formations with distinctive mineralogic propertiesNo change in contact angle with mineralogy, temperature (100°C), pressure (62 MPa), salinity (260,000 ppm), and bubble size (200–2,500 μm)Caprock minerals will remain water‐wet at geologic CO2 storage conditions and will not lose their capillary sealing capacity [ABSTRACT FROM AUTHOR]

In this study, cocrystallization of n-propylparaben and a ditopic bipyridine-based azine derivative in a 2 : 1 stoichiometric ratio was carried out. The resulting single crystals of the cocrystal displayed crystal-to-crystal polymorphic phase transformation on heating. The phase transformation is associated with naked-eye visible expansion and cracking of the single crystals. The two polymorphs are distinct in their surface wettability. [ABSTRACT FROM AUTHOR]

In this study, we investigate the stability of a film that is attached to a corner between a cylinder and a substrate, using a combination of theoretical and numerical approaches. Notably, we place our focus on flat and thin films where the contact line is almost perpendicular to the cylinder wall whereas a small angle forms between the contact line and the substrate, and the film size is smaller than the cylinder radius. The film stability, which depends on the film size and the wall wettability, is first predicted by a standard linear stability analysis (LSA) within the long-wave theoretical framework. We find that the film size plays the most important role in controlling the film stability. Specifically, the thicker the film is, the less sensitive it becomes to the large-wavenumber perturbation. The wall wettability mainly impacts the growth rates of perturbations and slightly influences the marginal stability and postinstability patterns of wrapping films. We compare the LSA predictions with numerical results obtained from a disjoining pressure model (DPM) and volume-of-fluid (VOF) simulations, which provide more insights into the film breakup process. At the early stage there is a strong agreement between the LSA predictions and the DPM results. Notably, as the perturbation grows, thin film regions connecting two neighbouring satellite droplets form which may eventually lead to a stable or temporary secondary droplet, an aspect which the LSA is incapable of capturing. In addition, the VOF simulations suggest that beyond a critical film size, merging between two neighbouring drops becomes involved during the breakup stage. Therefore, the LSA predictions are able to provide only an upper limit on the final number of satellite droplets. [ABSTRACT FROM AUTHOR]

To address the challenges of difficulty and low penetration speed of aqueous deacidification agents in paper, we aimed to enhance the wetting performance of these agents by incorporating a surfactant. We selected four surfactants for our study: anionic sodium dodecyl benzene sulfonate (SDBS), cationic cetyltrimethylammonium bromide (CTAB), nonionic polysorbate-80 (TW80), and polyether-modified trisiloxane (TRSE). The wetting properties of these surfactants on sodium propionate aqueous deacidification agent, the alkali stability of the solution, and the effects of moist heat aging on paper durability were explored. The results demonstrated that TRSE exhibited superior performance compared to the other three surfactants, effectively reducing the surface tension of sodium propionate solution to 21.02 mN/m. In alkaline conditions with a pH range of 8.00–10.00, the surface tension of SDBS, CTAB, and TW80 solutions remained stable for 30 days. Similarly, under weakly alkaline conditions with a pH value below 9, the surface tension of TRSE solutions exhibited stability. It should be noted that SDBS accelerated the decline of paper tensile index and whiteness during the heat and humidity aging process; at the same time, CTAB, TW80, and TRSE had no noticeable adverse effects on paper aging resistance. [ABSTRACT FROM AUTHOR]

Ion beam sputtering (IBS) can induce nanoripple patterns in a short time on variety of materials for wide range of applications. In this work, we describe the nanoripple as well as terrace pattern formation by IBS on soda-lime glass surfaces and the mechanisms leading to such pattern formations. The role of ion energy, ion fluence, and ion incidence angle on the morphology of the structural features is systematically explored. For a range of ion beam parameter values with energy varying from 600 to 1500 eV and fluence in the range 9.7 × 1017 to 2.0 × 1019 ions/cm2 at fixed incidence angle of 45°, transition of ripples to terraces has been observed. The experimental results are explained on the basis of recently modified KS equation which clearly explains the simultaneous role of nonlinear cubic term in the terrace formation. It is also demonstrated how ion beam can be used to tailor the wettability of glass surface and makes it hydrophobic in nature. Due to pattern formation, anisotropic hydrophobicity is observed showing an increasing trend owing to the magnification of the amplitude of nanopatterns developed on the surface. [ABSTRACT FROM AUTHOR]

Injectable hydrogels have emerged as versatile materials with potential applications in various fields, including biomedicine, lubrication, adhesion, surface coatings, and tissue engineering. However, the critical aspect of spreading and wetting on various substrates, which is essential for obtaining significant interfacial properties, has not been adequately addressed. This work presents an approach to prepare hydrogel coatings on kinds of substrates through the superspreading of polyelectrolyte complex solution during its liquid‐liquid phase inversion process. Due to the low interfacial tension, the solution spreads and wets various surfaces underwater driven by osmotic pressure, improving the contact area and interface integration. Combined with the simultaneous sol‐gel transition through electrostatic interaction, it forms a stable and homogeneous hydrogel coating. The hydrogel coating possesses control thickness (4–8 µm), improved hydrophilicity (CA decrease from 102° to 10°), interfacial toughness (increase from 70 to 455 J m−2), and lubrication performance (coefficients of friction decrease from 0.712 to 0.112). The work provides an excellent opportunity to investigate the spreadability and wettability in a water/water/solid three‐phase system and develop functional hydrogel coatings for various applications. [ABSTRACT FROM AUTHOR]

With the rapid development of the maritime industry, oily wastewater discharges and oil spills cause acute environmental challenges. Currently, cellulosic materials with switchable wettability have received increasing interest for oil–water separation. Moreover, work efficiency needs to be improved with a shorter response time. To realize these, dimethylaminoethyl methacrylate (DMAEMA) and methyltrimethoxysilane (MTMS) synthesized pH‐responsive copolymer (DMAEMA‐co‐MTMS) which grafted banana nanocellulose fiber made from wasted pseudostem to achieve the pH‐responsive aerogel (BCNA‐DcoM). BCNA‐DcoM exhibited hydrophilic/submerged lipophobicity under acidic conditions and hydrophobic/lipophilic under alkaline conditions. A response time of 3 s and a contact angle of 135° were shown when the mass ratio of banana nanocellulose suspension, MTMS, and DMAEMA‐co‐MTMS was 5:3:9. Moreover, BCNA‐DcoM possessed favorable mechanical friction properties, salt resistance (25% NaCl), compression resilience (50 cycles of compression at 60% strain), switchable wettability (>30 cycles), and highly efficient separation performance (>96%). The adsorption capacity of BCNA‐DcoM for oil is 80–184 times the initial weight of the aerogel based on the different oil densities. For practical applications, BCNA‐DcoM could continuously separate oil–water mixtures with the constant‐flow pump. The present work provides more possibilities for rapidly treating industrial oily wastewater with low‐cost and ecological banana pseudostem materials. [ABSTRACT FROM AUTHOR]

Conventional perfluorooctane sulfonyl fluorosurfactants (PFOS) have caused great harm to human health and the environment, but the irreplaceable properties of fluorosurfactants offer great values. To this end, we have synthesized a highly surface active, environmentally friendly sulfonate surfactant (PBSA) with a perfluorinated branched short chain and systematically investigated its thermal stability, surface properties, wetting performance, and so forth. The minimal surface tension (γCMC) and critical micelle concentration (CMC) of the aqueous solution of PBSA were 22.70 mN/m and 0.067 mmol/L, respectively. In addition, the binary system of PBSA and cetyltrimethylammonium bromide (CTAB) exhibited excellent synergistic effects: γCMC and CMC values were reduced to 18.94 mN/m and 0.008 mmol/L. Moreover, the PBSA/CTAB mixed solution exhibited superb wetting ability: it could achieve complete wetting of PTFE plates at low concentrations (1.82 × 10−3 mol/L), with a minimum wetting concentration of only 2.84 × 10−5 mol/L. [ABSTRACT FROM AUTHOR]

Functional liquid‐based interfaces, with their inhomogeneous regions that emphasize the functionalized liquids, have attracted much interest as a versatile platform for a broad spectrum of applications, from chemical manufacturing to practical uses. These interfaces leverage the physicochemical characteristics of liquids, alongside dynamic behaviors induced by macroscopic wettability and microscopic molecular exchange balance, to allow for tailored properties within their functional structures. In this Minireview, we provide a foundational overview of these functional interfaces, based on the structural investigations and molecular mechanisms of interaction forces that directly modulate functionalities. Then, we discuss design strategies that have been employed in recent applications, and the crucial aspects that require focus. Finally, we highlight the current challenges in functional liquid‐based interfaces and provide a perspective on future research directions. [ABSTRACT FROM AUTHOR]

The sustained water repellency of interconnected micropatterned surfaces is explored over an extended duration, with a focus on their resilience during a 90‐day water‐immersion test. Initially, the microstructure surfaces exhibit high water repellency, a characteristic of the Cassie–Baxter state. However, subsequent detailed temporal analyses reveal varying responses depending on the structural topology. The interconnected micropatterned surfaces exhibit remarkable long‐term resistance to water; this is attributed to the formation of large and stable air pockets enabled by their unique microcavity structures. In comparison, hierarchical microcavity surfaces with micropillars exhibit a notable decrease in water repellency, as evidenced by reduced contact angles, suggesting a transition to a wetting state owing to the emergence of surface hydrophilicity during long‐term water exposure. This study demonstrates the importance of stable air‐pocket effects, particularly in applications where the long‐term stability of liquid repellency is critical, and suggests the role of interconnected structures in maintaining water repellency over time. [ABSTRACT FROM AUTHOR]

Mountain regions are recognised as hot-spots of climate change. Although the existence of an Elevation-Dependent Warming has been extensively confirmed in several mountain areas of the globe, fewer studies have analysed the elevational stratification of temporal trends of other climate variables, and particularly for precipitation. This study analyses changes in mean precipitation and its extremes in ERA5 global reanalysis data in key mountain areas of the globe, along with their elevational dependence, from 1951 to 2020. These include the Tibetan Plateau, the US Rocky Mountains, the Greater Alpine Region, and the Andes, as representative of different latitudes and climatic influences. Our analysis reveals common patterns of elevational dependent change in precipitation and its extremes in most of the mountainous areas, which emerge beyond their geographical differences. A positive elevational gradient of trends of extreme precipitation indices is found in the Tibetan Plateau, the Greater Alpine Region, and the subtropical Andes, highlighting a wetting effect (positive trends) at very high elevations. In contrast, the Rocky Mountains exhibit a negative elevational gradient, with a drying effect (negative trends) increasing with the elevation. Notably, a simple linear regression proved to be effective to describe the stratification of change in the Greater Alpine Region and the Rocky Mountains, whereas more complex vertical patterns need to be considered for the Andes and the Tibetan Plateau. Mean precipitation, heavy (≥ 10 mm) precipitation and the length of consecutive wet days show a consistent elevation-dependent stratification within each of the study areas, suggesting possible common driving mechanisms. [ABSTRACT FROM AUTHOR]

The separation of specific-shaped nanoparticles from particle mixtures is important for the construction of particle domains with shape-specific characteristics. On the other hand, shape-based particle separation techniques have not received as much attention as size-based techniques. The shape separation effect of molecule-coated nanoparticles is primarily dependent on short-range steric interaction. The surfactant's geometrical arrangement determines the position of the nanoparticle's various crystallographic facets; this also determines how the various shapes are organized throughout the nanoparticle self-assembly process. In addition to smooth surfaces with a fixed droplet contact line and a stable environment, the self-assembled shape separation effect has been observed on surfaces with wettability stripe patterns and fluctuating environments where the droplet contact line behaves stick–slip-like during the evaporation process. The shape separation of spheres and rods is strongly influenced by steric interactions. Since shape-dependent transport properties exist in such nano-crystalline domains, it is important to understand the shape separation effect. Three different evaporation processes were used for the same suspension to study the shape dependent construction of gold nanostructures. Molecules covering the different crystallographic facets of the nanogold induced shape-selective assembly. Undisturbed evaporation of the rod-sphere arrays created separated liquid crystalline phases, and the gradient surface design and ultrasonically vibrating samples, which indicated short-range molecule dominance, drove a distinctive separation. [ABSTRACT FROM AUTHOR]

Relative permeability is a key parameter for characterizing the multiphase flow dynamics in porous media at macroscopic scale while it can be significantly impacted by wettability. Recently, it has been reported in microfluidic experiments that wettability is dependent on the pore size (Van Rooijen et al., 2022). To investigate the effect of pore‐size‐dependent wettability on relative permeability, we propose a theoretical framework informed by digital core samples to quantify the deviation of relative permeability curves due to wettability change. We find that the significance of impact is highly dependent on two factors: (i) the function between contact angle and pore size (ii) overall pore size distribution. Under linear function, this impact can be significant for tight porous media with a maximum deviation of 1,000%. Plain Language Summary: Relative permeability is an important feature for multiphase flow at the reservoir scale. It can be highly dependent on wettability, which is an interfacial property at the pore scale. Recent experimental evidence suggests that wettability is dependent on the pore size, but the impact of the pore‐size‐dependent wettability on relative permeability still remains unknown. In this study, we propose a theoretical model to investigate the effect of pore‐size‐dependent wettability on relative permeability. The pore size distribution is informed by the pore images. We find that the impact can be significant for low‐permeability porous media under certain conditions. The results imply that this effect is not always neglible when modeling two‐phase flow. Key Points: A theoretical framework is proposed to quantify the impact of pore‐size dependent wettability on relative permeabilityThe maximum impact on relative permeability can be as significant as 1,000% [ABSTRACT FROM AUTHOR]

Improving the durability of short-rotation wood can be achieved through chemical and thermal modification. Chemical and thermal modification can have an impact on the physicochemical properties of wood, which can affect wood's surface characteristics and its resistance to weathering. The purpose of this study was to investigate the surface characteristics and artificial weathering resistance of chemically and thermally modified short-rotation teak wood coated with linseed oil (LO)-, tung oil (TO)-, and commercial oil-based coatings consisting of a mixture of linseed oil and tung oil (LT) and commercial oil-based polyurethane resin (LB) coatings. The short-rotation teak woods were prepared in untreated and treated with furfuryl alcohol (FA), thermal treatment (HT) at 150 and 220 °C, and combination of glycerol–maleic anhydride (GMA) impregnation with thermal treatment at 150 and 220 °C. The surface characteristics measured were surface free energy, wettability, Persoz hardness, bonding quality, and color changes before and after artificial weathering exposure. The results showed that chemical and thermal modifications treatment tended to reduce total surface free energy (SFE), hardness, wettability, and bonding quality. FA and GMA at 220 °C treatments provided homogenization effect on surface characteristics, especially in total SFE and wettability. The total SFE of untreated wood ranged from 45.00 to 51.13 mN/m, and treated wood ranged from 40.58 to 50.79 mN/m. The wettability of oil-based coating according to K-value ranged from 0.20 to 0.54. TO presented better photostability than LO. Short-rotation teak wood coated with oil-based commercial coatings presented better weathering resistance compared to pure natural drying oil. Commercial oil-based coatings provided better weathering protection for the chemically and thermally modified teak wood. The application of oil-based coatings on chemically and thermally modified short-rotation teak is being considered for the development of a better wood-protection system. [ABSTRACT FROM AUTHOR]

Pure titanium is a preferred material for medical applications due to its outstanding properties, and the fabrication of its surface microtexture proves to be an effective method for further improving its surface-related functional properties, albeit imposing high demands on the processing accuracy of surface microtexture. Currently, we investigate the fabrication of precise microtextures on pure titanium surfaces with different grid depths using precision-cutting methods, as well as assess its impact on surface wettability through a combination of experiments and finite element simulations. Specifically, a finite element model is established for pure titanium precision cutting, which can predict the surface formation behavior during the cutting process and further reveal its dependence on cutting parameters. Based on this, precision-cutting experiments were performed to explore the effect of cutting parameters on the morphology of microtextured pure titanium with which optimized cutting parameters for high-precision microtextures and uniform feature size were obtained. Subsequent surface wettability measurement experiments demonstrated from a macroscopic perspective that the increase in the grid depth of the microtexture increases the surface roughness, thereby enhancing the hydrophilicity. Corresponding fluid–solid coupling finite-element simulation is carried out to demonstrate from a microscopic perspective that the increase in the grid depth of the microtexture decreases the cohesive force inside the droplet, thereby enhancing the hydrophilicity. [ABSTRACT FROM AUTHOR]

Nature provides us with a wealth of inspiration for the design of bionic functional surfaces. Numerous types of plant leaves with exceptional wettability, anisotropy, and adhesion are extensively employed in many engineering applications. Inspired by the wettability, anisotropy, and adhesion of indocalamus leaves, bionic upper and lower surfaces (BUSs and BLSs) of the indocalamus leaf were successfully prepared using a facile approach combining laser scanning and chemical modification. The results demonstrated the BUSs and BLSs obtained similar structural features to the upper and lower surfaces of the indocalamus leaf and exhibited enhanced and more-controllable wettability, anisotropy, and adhesion. More importantly, we conducted a detailed comparative analysis of the wettability, anisotropy, and adhesion between BUSs and BLSs. Finally, BUSs and BLSs were also explored for the corresponding potential applications, including self-cleaning, liquid manipulation, and fog collection, thereby broadening their practical utility. We believe that this study can contribute to the enrichment of the research on novel biological models and provide significant insights into the development of multifunctional bionic surfaces. [ABSTRACT FROM AUTHOR]

Water pollution seriously affects the development of society and human life. There are various kinds of pollutants, including soluble pollutants and insoluble floaters on the water surface. Herein, the photocatalyst semiconductor BiOCl and superhydrophobic functional particles Mg(OH)2 were deposited on the surfaces of canvas and polyester felt to construct superhydrophobic canvas and polyester felt. The contact angles of the synthetic superhydrophobic canvas and polyester felt were measured as 152° and 155.3°, respectively. The selective adsorption of hexadecane was achieved using the wetting difference between the surface of water and pollutants floating on the surface. For dissolved pollutants, the surface wettability needed to be changed with the help of ethanol. The degradation efficiencies were all greater than 90%, demonstrating the versatility of the synthetic superhydrophobic canvas and polyester felt. [ABSTRACT FROM AUTHOR]

When a droplet off-center impacts a macro-ridge, it may split into two asymmetric fragments, i.e., the smaller part (SP) and larger part (LP), which then exhibit asymmetric spreading and receding phenomena. Using lattice Boltzmann method simulations, the dynamics of a droplet off-center impacting a hydrophobic surface are explored for the first time. Influences of the off-center distance, the impact Weber number, and the surface wettability on the impact outcomes and the contact time are elucidated, and the impact regime is established. Six impact outcomes are discovered as off-center distance changes, which are dependent on the interaction force between the droplet and the surface. The effect of the off-center distance and the Weber numbers on the spreading and the receding dynamics of the SP is more obvious than that of the LP, due to the fact that adhesion of the ridge on the LP can be negligible compared to the inertial force and the surface tension. The contact time is closely related to the impact outcomes, that is, when the impact outcome is type 1 (SP and LP separate rebound), the contact time can be significantly reduced compared with that on the flat hydrophobic surface, due to the fact that the ridge can reduce the asymmetry of a liquid film and the receding distance in this case; while when the impact outcome is type 6 (SP and LP completely coalescence and rebound), the contact time cannot be reduced. This work extends the fundamental knowledge of off-center impact and provides inspiration for the efficient reduction in the contact time. [ABSTRACT FROM AUTHOR]

Horizontal transport of droplets is important for anti-icing, self-cleaning, and water collection technologies. In this paper, the bouncing dynamics of two off-center droplets impacting on a solid surface are explored via numerical simulations. Two kinds of surface wettability are considered. One is a superhydrophobic surface (homogeneous wettability), and the other is a superhydrophobic surface arranged with a hydrophilic strip (heterogeneous wettability). First, the effect of an eccentric angle on the horizontal transport of two droplets impacting on a homogeneous wettability surface is investigated. As the eccentric angle increases, the merged droplet after impact may experience horizontal transportation in either the positive or negative direction. When a heterogeneous wettability surface is adopted, the changes in the transport direction of the merged droplet are consistent with the location of the hydrophilic strip upon eccentric impact. By adjusting the position of the hydrophilic strip, the maximum horizontal transportation distance is 7.53 times the diameter of the initial droplet when the eccentric angle is 10°, while it is only 2.01 times the diameter of the initial droplet when the eccentric angle is 20° for a homogeneous wettability surface. It is indicated that the use of the heterogeneous wettability surface is significantly efficient for droplet control after impact. The obtained results contribute to the fundamental understanding of droplet directional migration and are valuable for related engineering applications. [ABSTRACT FROM AUTHOR]

We report here multiphase direct numerical simulations of a recently discovered passive mechanism of self-cleaning on superhydrophobic surfaces. The removal of contaminants is governed by coalescence of a single droplet with a particle of micrometer size, where the droplet initiates spontaneous spreading on the particle and drives particle–droplet jumping. We use an in-house volume of fluid–immersed boundary numerical framework, introduce and thoroughly analyze capillary forces at the particle–droplet contact line, and validate our simulations in relation to previous experimental results. We then perform a comprehensive investigation over a number of different parameters regarding the interaction physics of the droplet with the particle and the substrate. We systematically vary particle, droplet, and surface physical and wetting properties and unveil a range of scenarios related to different energy dissipation mechanisms as a function of the substrate contact angles and contact-angle hysteresis. Detailed parameter studies establish the connection between the droplet, substrate and particle properties, and the outcome and efficiency of the particle-launching process. We particularly highlight the effects of the particle–droplet size ratio and the wettability of the particle. We reveal and discuss the corresponding dissipation mechanisms and quantify the energy efficiencies of the jumping process in the treated parameter space. [ABSTRACT FROM AUTHOR]

Superhydrophobic surfaces can seal the gas–liquid interface (GLI) under water to produce the drag reduction effect. Enhancing the stability and slip length of the GLI is an important issue in this context. Herein, we fabricate wettability step electrodes (WSEs) by creating an array of millimeter-scale circular superhydrophobic regions on a hydrophilic graphite plate by using an economical and efficient mask spraying method. When the WSE was electrified as an anode, the oxygen produced by the electrolytic reaction was preferentially precipitated in the superhydrophobic regions and ultimately formed an array of millimeter-scale GLIs. The evolution process of this GLI can be divided into a spreading stage and a growth stage. The results of experiments revealed that the spreading duration of the GLI increased with the diameter of the superhydrophobic regions (D) and decreased with the spacing between adjacent superhydrophobic regions (L). During the growth stage, the height of the GLI decreased with the ratio D/(L + D) and increased over the duration of electrification according to a 1/3 power-law relationship. Finally, we measured the slip characteristic on a single millimeter-scale GLI by particle image velocimetry. The result showed that the effective slip length of the GLI with a streamwise length of 2 mm can exceed 100 μm, thus confirming the potential of the millimeter-scale GLI for drag reduction. [ABSTRACT FROM AUTHOR]