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In this study, low-cost laser marker ablation of vanadium-coated glass was adopted to prepare self-cleaning, anti-reflective, and anti-fog micro-nano structures on its surface. The surface had a hierarchical micro-nano structure composed of a quasi-periodic microstructure and ∼100 nm-sized worm-like clusters interspersed with dispersed nanoparticles. The solar spectrum (AM 1.5) weighted average transmission of treated glass was enhanced by 3.87% over control glass in the wavelength range of 400–1100 nm. Importantly, the water contact angle of the laser-treated samples achieved and maintained 0° for a duration of 25 days, and the laser-treated samples achieved and maintained excellent anti-fog performance for 150 days. The antifog performance degraded substantially afterward, though was still noticeable compared to the reference even after 428 days of storage in the laboratory. Furthermore, co-achievement of exceptional self-cleaning anti-fog performance and broadband transmission enhancement through laser treatment of glass has rarely been previously reported. [ABSTRACT FROM AUTHOR]

We energetically predict the morphology of Pd, Ag, Au, and Pt nanoparticles on (0001) sapphire substrates, using density functional theory (DFT) simulations and the well-known Young–Dupre equation. In all cases, the contact angles exceed 90 ° , indicating that the nanoparticles are spherical. Notably, Au nanoparticles exhibit a higher contact angle than those of their counterparts. The validity of the proposed a b i n i t i o nanoparticle morphology prediction approach based on DFT simulations was assessed in comparison with our previous experimental findings pertaining to the time variation of the full width at half maximum (FWHM) of the resonant peak. Furthermore, the diffusivities of single Pd, Ag, Au, and Pt atoms on the substrate were evaluated by calculating the activation energy, offering insights into the underlying physics governing the timing of FWHM peaks. The analysis confirms a higher diffusivity of Au and Ag compared with Pd and Pt. According to the comparison between DFT and experiment results, although no clear relation is observed between the contact angles and timing of FWHM peaks, the diffusivity of sputtered atoms may influence the timing of FWHM peaks. Thus, timing can help to clarify the nanoparticle size, rather than shape. [ABSTRACT FROM AUTHOR]

The rapid realization of efficient anti-icing coatings on diverse substrates is of vital value for practical applications. However, current approaches for rapid preparations of anti-icing coatings are still deficient regarding their surface universality and accessibility. Here, we report a simple processing approach to rapidly form icephobic liquid-like polydimethylsiloxane (PDMS) brushes on various substrates, including metals, ceramics, glass, and plastics. A poly(dimethylsiloxane), trimethoxysilane is applied as a reactant under the catalysis of a minimal amount of acid formed by hydrolysis of dichlorodimethylsilane. With such an advantage, this approach is approved to be applicable of coating metal surfaces with less corrosion. The distinctive flexibility of the PDMS chains provides a liquid-like property to the coating showing low contact angle hysteresis and ice adhesion strength. Notably, the ice adhesion strength remains similar across a wide temperature window, from −70 to −10 °C, with a value of 18.4 kPa. The PDMS brushes demonstrate perfect capability for resisting acid and alkali corrosions, ultra-violet degradation, and even tens of icing/deicing cycles. Moreover, the liquid-like coating can also form at supercooling conditions, such as −20 °C, and shows an outstanding anti-icing/deicing performance, which meets the in situ coating reformation requirement under extreme conditions when it is damaged. This instantly forming anti-icing material will benefit from resisting instantaneous ice accretion on surfaces under extremely cold conditions. [ABSTRACT FROM AUTHOR]

In this work, we implemented an off-axis digital holographic microscopy (DHM) setup to study the behavior of liquid drops on nanostructured porous silicon (PS) membranes. When a liquid comes into contact with the PS structure, capillary action and surface tension give rise to imbibition of the liquid into the intricate volume of the pores. At the same time, the vapor field developed around the drop enhances liquid condensation and evaporation into and from the pores. The complex interplay between these phenomena (capillary driven internal flows, condensation, and evaporation) is not yet fully understood but the methods we propose can provide new insights. We demonstrate how DHM allows determining the filling fraction of the porous membrane around drying drops of water and isobutyl alcohol. The phase information obtained from registered holograms provides quantitative information that permits to reconstruct the filling fraction along the porous membrane and its evolution during the drying process. Additionally, relevant parameters such as speed and contact angle during retraction of the drops can be measured. These methods can be further extended to other porous materials, such as porous alumina, micro- and macro-PS, to develop better fluid-dynamic models for describing fluid behavior in highly confined structures. [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]

Hydrophobicity has proven fundamental in an inexhaustible amount of everyday applications. Material hydrophobicity is determined by chemical composition and geometrical characteristics of its macroscopic surface. Surface roughness or texturing enhances intrinsic hydrophilic or hydrophobic characteristics of a material. Here we consider crystalline surfaces presenting molecular-scale texturing typical of crystalline porous materials, e.g., metal-organic frameworks. In particular, we investigate one such material with remarkable hydrophobic qualities, ZIF-8. We show that ZIF-8 hydrophobicity is driven not only by its chemical composition but also its sub-nanoscale surface corrugations, a physical enhancement rare amongst hydrophobes. Studying ZIF-8's hydrophobic properties is challenging as experimentally it is difficult to distinguish between the materials' and the macroscopic corrugations' contributions to the hydrophobicity. The computational contact angle determination is also difficult as the standard "geometric" technique of liquid nanodroplet deposition is prone to many artifacts. Here, we characterise ZIF-8 hydrophobicity via: (i) the "geometric" approach and (ii) the "energetic" method, utilising the Young–Dupré formula and computationally determining the liquid–solid adhesion energy. Both approaches reveal nanoscale Wenzel-like bathing of the corrugated surface. Moreover, we illustrate the importance of surface linker termination in ZIF-8 hydrophobicity, which reduces when varied from sp3 N to sp2 N termination. We also consider halogenated analogues of the methyl-imidazole linker, which promote the transition from nanoWenzel-like to nanoCassie–Baxter-like states, further enhancing surface hydrophobicity. Present results reveal the complex interface physics and chemistry between water and complex porous, molecular crystalline surfaces, providing a hint to tune their hydrophobicity. [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]

The stability of holes in solid thin films is crucial, as an absence of holes is necessary in some applications and holes are needed in others. We develop an axisymmetric two grain model with a central hole, with surface diffusion governing the exterior surfaces and mean curvature motion governing the grain boundary. The model can exhibit grooving, wetting, dewetting, as well as void, hole, and hillock formation. Here, we extend an earlier work [Zigelman and Novick-Cohen, J. Appl. Phys. 130, 175301 (2021)], where it was shown for an axisymmetric single grain system with a hole at the center that there exists a critical effective radius, which is independent of the contact angle. The stability of the steady states, which consist of coupled nodoidal and catenoidal surfaces, is analyzed numerically by imposing the steady state configurations as initial conditions. This approach yields stability criteria in terms of (i) the effective energy, (ii) the ratio between the maximal thickness of the inner and outer grains, (iii) a generalized effective radius, and (iv) the ratio between the mean curvature of the exterior surfaces and the total volume of the system. Some of these criteria partially reflect the Rayleigh stability criterion. Hillock formation tends to be stabilizing. Modes of instability include growth of one grain at the expense of the other, breakup induced by grooving, and hole closure. [ABSTRACT FROM AUTHOR]

Micro–nano symbiotic superamphiphobic surfaces can prevent liquids from adhering to metal surfaces and, as a result, improve their corrosion resistance, self-cleaning performance, pollution resistance, and ice resistance. However, the fabrication of stable and controllable micro–nano symbiotic superamphiphobic structures on metal surfaces commonly used in industry remains a significant challenge. In this study, a laser-electrochemical hybrid subtractive–additive manufacturing method was proposed and developed for preparing copper superamphiphobic surfaces. Both experimental and fluid simulation studies were carried out. Utilizing this novel hybrid method, the controllable preparation of superamphiphobic micro–nano symbiotic structures was realized. The experimental results showed that the prepared surfaces had excellent superamphiphobic properties following subsequent modification with low surface energy substances. The contact angles of water droplets and oil droplets on the surface following electrodeposition treatment reached values of 161 ± 4° and 151 ± 4°, respectively, which showed that the prepared surface possessed perfect superamphiphobicity. Both the fabrication method and the test results provided useful insights for the preparation of stable and controllable superamphiphobic structures on metal surfaces in the future. [ABSTRACT FROM AUTHOR]

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

The microscopic processes involving droplet impact and interaction on spatially curved surfaces remain unclear. In this study, we implement a dynamic contact angle model with adjusted upper and lower limits into a simulation of droplet motion, constructing a three-dimensional numerical model to depict the dynamics and heat transfer characteristics of symmetric double droplets impacting plane, concave, and convex cylindrical, and concave and convex spherical surfaces. The processes of droplet spreading, retraction, rebound, splitting, and heat transfer are elaborated, revealing the role of surface curvature during impact. Our results show that different curvatures significantly affect the flow morphology of the flow dividing line. For the two main curvatures of the surface, the curvature in the direction of droplet arrangement predominates. Positive curvature promotes spreading and repels the liquid phase, while negative curvature promotes agglomeration and attracts the liquid phase. Extreme situations arise when both positive and negative curvatures occur simultaneously. Regarding heat transfer, the overall heat transfer rate is mainly determined by the spread area, and the heat transfer performance of convex surfaces is better than that of plane or concave surfaces. Residual bubbles increase heat transfer inhomogeneity, but different surfaces do not show significant variability. Additionally, the heat flow intensity in the central interaction region has the following relationship with its rebound height and is independent of the overall heat transfer intensity. [ABSTRACT FROM AUTHOR]

We perform numerical and experimental studies on the melting process of thin films initiated by a small hole in the continuum regime. The presence of a nontrivial capillary surface, namely the liquid/air interface, leads to a few counterintuitive results: (1) The melting point is elevated if the film surface is partially wettable, even with a small contact angle. (2) For a film that is finite in size, melting may prefer to start from the outer boundary rather than a hole inside. (3) More complex melting scenarios may arise, including morphology transitions and the "de facto" melting point being a range instead of a single value. These are verified by experiments on melting alkane films between silica and air. This work continues a series of investigations on the capillary aspects of melting. Both our model and analysis approach can be easily generalized to other systems. [ABSTRACT FROM AUTHOR]

The capture of moisture from the atmosphere through condensation has the potential to provide a sustainable source of water. Here, we investigate the condensation of humid air at low subcooling condition (11 °C), similar to conditions for natural dew capture, and explore how water contact angle and contact angle hysteresis affect the rates of water capture. We compare water collection on three families of surfaces: (i) hydrophilic (polyethylene oxide, MPEO) and hydrophobic (polydimethylsiloxane, PDMS) molecularly thin coatings grafted on smooth silicon wafers, which produce slippery covalently attached liquid surfaces (SCALSs), with low contact angle hysteresis (CAH = 6°); (ii) the same coatings grafted on rougher glass, with high CAH (20°–25°); (iii) hydrophilic polymer surfaces [poly(N-vinylpyrrolidone), PNVP] with high CAH (30°). Upon exposure to water, the MPEO SCALS swell, which likely further increases their droplet shedding ability. MPEO and PDMS coatings collect similar volume of water (around 5 l m−2 day−1), both when they are SCALS and non-slippery. Both MPEO and PDMS layers collect about 20% more water than PNVP surfaces. We present a basic model showing that, under low heat flux conditions, on all MPEO and PDMS layers, the droplets are so small (600–2000 µm) that there is no/low heat conduction resistance across the droplets, irrespective of the exact value of contact angle and CAH. As the time to first droplet departure is much faster on MPEO SCALS (28 min) than on PDMS SCALS (90 min), slippery hydrophilic surfaces are preferable in dew collection applications where the collection time frame is limited. [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 investigated the influence of steel surface properties on the wettability of zinc (Zn). Our main objective is to address the selective oxidation of solute alloying elements and enhance the wetting behavior of Zn on advanced high strength steel (AHSS) by employing an aluminum (Al) interlayer through the physical vapor deposition technique. The deposition of an Al interlayer resulted in a decrease in contact angle and an increase in spread width as the molten Zn interacted with the Al interlay on the steel substrate. Importantly, the incorporation of an Al interlayer demonstrated a significant improvement in wettability by substantially increasing the work of adhesion compared to the uncoated AHSS substrate.

Abstract This study aims to prepare mono and gemini nonionic emulsifiers differing in HLB to utilize in formulated metal cutting fluids. Also, the cationic gemini surfactant (GCS) was prepared and applied as a corrosion inhibitor and biocide in the formulations. FT-IR and NMR confirmed the chemical structure of the prepared compounds. Different oil package formulations were prepared by adding different trial concentrations of the additives (emulsifier, corrosion inhibitor, coupling agent, and biocide) to the eco-friendly vegetable oil (castor oil). Standard procedures were performed to assess the stability of the formulated base oil packages. Six Formulas demonstrated the greatest oil stability. Oil in water emulsions with varying formulated oil ratios (5–15 wt%) were prepared. A standard test was carried out to evaluate their performance as emulsion stability. It’s been demonstrated that Formulas II and V produced stable emulsions. The wettability alteration of formulas II and V on different metal surfaces was evaluated. The droplet size of formulated castor oil in water was determined via DLS. Corrosion test and tribological properties were also performed. The findings of this study indicate that Formula V is a good choice as a renewable addition for enhancing a variety of performance characteristics of the water-based cutting fluid.

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]

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]

Polymers conjugated with active agents have applications in biomedicine, anticorrosion, and smart agriculture. When the active agent is used as a drug, corrosion inhibitor, or pesticide, it can be released upon a specific stimulus. The efficiency and the sustainability of active agents are determined by the released kinetics. In this work, we study the fast-release kinetics of 8-hydroxyquinoline (8HQ) from a pH-responsive, random copolymer of methyl methacrylate and 8-quinolinyl-sulfide-ethyl acrylate [P(MMA-co-HQSEA)] by hydrolysis of the β-thiopropionate groups. We used contact angle measurements of sliding drops as an elegant way to characterize the release kinetics. Based on the results gained from 1H nuclear magnetic resonance measurement, fluorescent intensity measurement, and velocity-dependent contact angle measurement, we found that both the hydrolysis rate and polymer conformation affect the release kinetics of 8HQ from a P(MMA-co-HQSEA) film. Polymer chains collapse and further suppress the release from the inner layer in acidic conditions, while polymer chains in a stretched condition further facilitate the release from the inner layer. As a result, the cumulative release rate of 8HQ is higher in the basic condition than in the acidic condition. [ABSTRACT FROM AUTHOR]

The present investigation assesses a variety of parameters available in the literature to model gold–water interfaces using molecular dynamics simulations. The study elucidates the challenges of characterizing the solid–liquid affinity of highly hydrophilic gold–water interfaces via wettability. As an alternative, the local pairwise interaction energy was used to describe the solid–liquid affinity of flat and curved surfaces, where for the latter, the calculation of a contact angle becomes virtually impossible. Regarding the heat transfer properties of different interface models (flat and curved), partly conclusive trends were observed between the total pairwise interaction energy and the thermal boundary conductance. It was observed that the solid surface structure, interfacial force field type, and force field parameters created a characteristic bias in the interfacial water molecules (liquid structuring). Consequently, a study of the liquid depletion layer provided better insight into the interfacial heat transfer among different interfaces. By computing the density depletion length, which describes the deficit or surplus of energy carries (water molecules) near the interface, a proper characterization of the thermal boundary conductance was obtained for the different gold–water interfaces. It was observed that the interfacial heat transfer is favored when the water molecules organize in cluster-like structures near the interface, by a surplus of water molecules at the interface, i.e., lower density depletion length, and by the closeness of water to the solid atoms. [ABSTRACT FROM AUTHOR]

Porous solid films that promote large apparent contact angles are interesting systems since their wetting properties are dependent on both the surface structure and water penetration into the film. In this study, a parahydrophobic coating is made by sequential dip coating of titanium dioxide nanoparticles and stearic acid on polished copper substrates. The apparent contact angles are determined using the tilted plate method, and it is found that the liquid–vapor interaction decreases and water droplets are more likely to move off the film when the number of coated layers increases. Interestingly, it is found that under some conditions, the front contact angle can be smaller than the back contact angle. Scanning electron microscopy observations demonstrate that the coating process led to the formation of hydrophilic TiO2 nanoparticle domains and hydrophobic stearic acid flakes that allows heterogeneous wetting. By monitoring the electrical current through the water droplet to the copper substrate, it is found that the water drops penetrate the coating layer to make direct contact with the copper surface with a time delay and magnitude that depends on the coating thickness. This additional penetration of water into the porous film enhances the adhesion of the droplet to the film and provides a clue to understand the contact angle hysteresis. [ABSTRACT FROM AUTHOR]

BACKGROUND: Nanostructure modification of pure titanium surface is a hot research field of titanium implant surface treatment. OBJECTIVE: To evaluate the effect of nano-modified titanium surface treated with alkali heat treatment on early adhesion and growth of osteoblasts. METHODS: Four-grade pure titanium sheets with a diameter of 15 mm and a thickness of 1.5 mm were taken and processed in three groups: the smooth treatment group was polished step by step with 250 mesh, 800 mesh, and 1 500 mesh silicon carbide sandpaper. In the sandblasting group, the smoothed titanium sheet was sandblasted with 100 μm Al2O3 particles at 0.45 MPa pressure, and then the acid etching was carried out. In the alkali heat treatment group, the smoothed titanium sheet was placed in the reactor, immersed in 10 mol/L NaOH solution, and heated in the oven at 100 °C for 12 hours. The surface morphology, roughness, and hydrophilicity of three groups of titanium sheets were measured. MG63 osteoblasts were inoculated on the surface of three groups of titanium tablets, and the adhesion of the cells was observed by immunofluorescence staining. RESULTS AND CONCLUSION: (1) Scanning electron microscopy showed that the surface of titanium sheets in the smooth treatment group had uniform scratches; the surface of titanium sheets in the sandblasting group was uneven, and the surface of titanium sheets in the alkali heat treatment group had uniform nanoscale three-dimensional pore morphology. The roughness value of the titanium sheets in sandblasting and alkali heat treatment groups was higher than that in the smooth treatment group (P < 0.05), and the water contact angle was lower than that in the smooth treatment group (P < 0.05). (2) Immunofluorescence staining after 3 and 6 hours of inoculation of MG63 cells showed that the number of adhesion cells on the surface of the titanium sheet in the sandblasting group and alkali heat treatment group was higher than that in the smooth treatment group (P < 0.05). Immunofluorescence staining 12 hours after inoculation showed that compared with the smooth treatment group, the actin skeleton of cells on the surface of titanium sheets in the sandblasting group and alkali heat treatment group was more extended, and most cells extended stronger pseudopodia, which was conducive to subsequent intercellular signal transduction and intercellular interaction. (3) The results showed that the nanostructures with certain biological activity could be prepared on the surface of a titanium sheet by alkali heat treatment, which was conducive to the early adhesion of osteoblasts. [ABSTRACT FROM AUTHOR]

Synthesis of the MAX phase is most often conducted at high temperatures, and the synthesized mixture contains many contaminant phases that require removal. The discovery of efficient low-temperature methods for the synthesis of MAX phases and MXenes is the key to their mass application. This work reports a method for obtaining pure MAX-phase with composition of Cr 2 GaC using a microwave reactor without additional heating. Synthesis was performed under 2 torr vacuum in hydrogen and methane flows of 80 and 20 sccm, respectively. The power of the microwave generator was 500 W at a frequency of 4.5 GHz. The synthesis process consists of creating conditions for capillary interaction (contact angle much lower than 90°, tends to zero), dissolution of chromium substrate in liquid gallium and dissolution of carbon directly from the gas phase (H 2 –CH 4 plasma). The synthesized MAX phase does not contain any phase contaminations and has a thickness of several atomic layers and submicron lateral dimensions. Characterization of the phases was carried out using the transmission electron microscopy (TEM), energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), atomic-force microscopy (AFM), X-ray diffraction (XRD) and Raman spectroscopy methods. Diffraction methods show high purity of Cr 2 GaC phase synthesized by this method, which can be a good precursor for MXenes production. [ABSTRACT FROM AUTHOR]

In this investigation, a geopolymer based on ceramic waste (CW) and granulated blast furnace slag (GBFS) was synthesized. To confer the geopolymer with self-cleaning functionality, a nano-SiO 2 -TiO 2 coating with hydrophobic and photocatalytic properties was applied onto the surface of CW-GBFS-based geopolymer. The effect of both the CW content and the alkali activator modulus (molar ratio of SiO 2 /Na 2 O) on the compressive strength of the geopolymer was evaluated. The highest compressive strength of 45.6 MPa was attained at 7 days with a composition containing 40 wt% of CW and an alkali activator modulus of 1.4. Furthermore, the geopolymer with the most desirable compressive strength was selected for the preparation of SiO 2 –TiO 2 /CW-GBFS-based geopolymer (ST/CGG). The effect of nano-SiO 2 -TiO 2 dosage on the self-cleaning performance of ST/CGG was explored. The self-cleaning surface of the ST/CGG had a maximum water contact angle of 118° when the addition of SiO 2 and TiO 2 was 5.8 wt%. Moreover, the surface of the ST/CGG underwent testing for methyl orange degradation, ultraviolet–visible diffuse reflectance spectral analysis, oleic acid decomposition, and bauxite residue removal, validating its superior photocatalytic self-cleaning efficacy. Overall, this work not only highlights the potential of ceramic waste utilization for geopolymers, but also provides a feasible strategy for developing functional geopolymers with self-cleaning ability. [ABSTRACT FROM AUTHOR]

This study describes the fabrication of electrospun casein/PVA nanofibers containing metal-organic framework (MOF) with antibacterial and hemostatic properties. Different amounts of MOF particles (1–5 wt.%) were incorporated into casein/PVA nanofibers through a concurrent electrospinning technique. The surface property, structure, and morphology of fabricated nanofibrous composites were characterized by different techniques, including field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and contact angle measurement. The results revealed the formation of uniform and bead-free nanofibers with an average diameter between 80 and 150 nm. It is shown that the MOF addition during the electrospinning of casein/PVA nanofibers enhances the wettability properties and hemostatic performance. The highest hydrophilicity was obtained for casein/PVA-MOF-1% with a contact angle of about 42°. Blood clotting time results revealed the significant role of MOF in the shortening of the clotting time, beneficial from the porous nature of MOF and the hydrophilic nature of casein/PVA-MOF nanofibrous composites. Additionally, the casein/PVA-MOF nanofibrous composites exhibited excellent antibacterial activity against gram-positive and gram-negative bacteria, thanks to the presence of zinc-based MOF. The results of this study suggest that the developed casein/PVA-MOF nanofibrous composite can be considered an excellent candidate for utilization in hemostatic wound dressing applications. [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] Pickering emulsions have attracted increasing attention from multiple fields, including food, cosmetics, healthcare, pharmaceutical, and agriculture. Their stability relies on the presence of colloidal particles instead of surfactant at the droplet interface, providing steric stabilization. Here, we demonstrate the microscopic attachment and detachment of particles with tunable contact angle at the interface underlying the Pickering emulsion stability. We vary the interfacial tension continuously by varying the temperature offset of a phase-separated binary liquid from its critical point, and employ confocal microscopy to directly observe the particles at the interface to determine their coverage and contact angle as a function of the varying interfacial tension. When the interfacial tension decreases upon approaching the binary liquid's critical point, the contact angle and detachment energy (ΔE) drop, and the particles move out of the interface. Microscopic imaging suggests necking and capillary interactions lead to clustering of the particles, before they eventually desorb from the interface. Macroscopic measurements show that concomitantly, coalescence takes place, and the emulsion loses its stability. These results reveal the interplay of interfacial energies, contact angle and surface coverage that underlies the Pickering emulsion stability, opening up ways to manipulate and design the stability through the microscopic behavior of the adsorbed particles. [ABSTRACT FROM AUTHOR]

Superhydrophobic surfaces are used in fields such as self-cleaning, anti-corrosion and anti-rust, and electromagnetic shielding because they are not wetted by water droplets. We manipulated the scanning spacing and scanning times of the femtosecond laser to control the surface morphology of alumina ceramics, resulting in the creation of two microstructures: micropillars and microhills. Subsequent heat treatment in an oven at 100 °C for 12 h formed a superhydrophobic surface without additional chemical modification, with a contact angle as high as 171.706°. Experimental results show that the superhydrophobicity of the alumina ceramic surface is due to the micro-nano structure of the ceramic surface under specific laser parameters and the hydroxylation of the alumina ceramic itself combined with organic compounds in the air. In addition, the ceramic still has excellent superhydrophobic properties up to 155° after being left in the air for 35 days and abraded by 800-grit sandpaper for 1 m under a pressure of 2.2kpa. Our work uses a new environmentally friendly method to make alumina ceramic surfaces both wear-resistant and superhydrophobic. [ABSTRACT FROM AUTHOR]

Casein proteins were cross-linked with dialdehyde tragacanth gum (DTG) to create a film with improved physico-mechanical properties. The DTG/casein film with a 2:1 ratio exhibited good physical and barrier properties, such as tensile strength (TS) (12.92 MPa), water contact angle (WCA) (73.2°), water vapor permeability (WVP) (2.1 × 10 − 10 g·mm/h·mm2·Pa), and water solubility (WS) (22.3%). Carbon dot (CD) nanoparticles were synthesized from milk permeate using a hydrothermal method. CDs (5 to 50% w/w) were incorporated into the optimal cross-linked casein films to create casein-based nanocomposites. Adding CDs (up to 15% w/w) increased the film's tensile strength by 36%. Scanning electron microscopy (SEM) confirmed the homogeneous distribution of 5% CD in the films without aggregation. The hydrophilicity of the films increased with the addition of CDs. Additionally, incorporating CDs significantly reduced UV transmission, with a 99.09% reduction in UV-C and a 97.46% reduction in UV-A. The CD-added nanocomposite films demonstrated potent antioxidant activity, increasing DPPH scavenging from 18.1 to 94% and ABTS scavenging from 16.4 to 89.3%. No cytotoxicity was observed in normal cells (HUVEC) even after 72 h of exposure. Coating butter products with the composite films for 60 days resulted in decreased peroxide value (PV) and thiobarbituric acid reactive substances (TBARS), indicating an oxidation–reduction process. These findings highlight the potential of cross-linked casein films with CDs to extend the shelf life of food products in the food industry. [ABSTRACT FROM AUTHOR]

Background: Advances in regeneration methods have brought us improved vascular scaffolds with small diameters (φ < 6 mm) for enhancing biological suitability that solve their propensity for causing intimal hyperplasia post‐transplantation. Methods: The correlation between the rehydration ratio of the hydrogel and its material concentration is obtained by adjusting the material ratio of the hydrogel solution. The vascular model with helical structure has been established and analyzed to verify the effect of helical microvascular structure on thrombosis formation by the fluid simulation methods. Then, the helical structure vascular has been fabricated by self‐developed 3D bioprinter, the vascular scaffolds are freeze‐dried and rehydrated in polyethylene glycol (PEG) solution. Results: The experimental results showed that the hybrid hydrogel had a qualified rehydration ratio when the content of gelatin, sodium alginate, and glycerol was 5, 6, and 3 wt%. The established flow channel model can effectively reduce thrombus deposition and improve long‐term patency ratio. After PEG solution modification, the contact angle of the inner wall of the vascular scaffold was less than 30°, showing better hydrophilic characteristics. Conclusion: In study, a small‐diameter inner wall vascular scaffold with better long‐term patency was successfully designed and prepared by wrinkling and PEG modification of the inner wall of the vascular scaffold. This study not only creates small‐diameter vascular scaffolds with helical structure that improves the surface hydrophilicity to reduce the risk of thrombosis but also rekindles confidence in the regeneration of small caliber vascular structures. [ABSTRACT FROM AUTHOR]

A method of preparing SiO2‐BNNSs hybrid material by surface modification of boron nitride nanosheets (BNNSs) with SiO2 was proposed to improve the dispersion of BNNSs in the coatings. Then, phosphate ceramic coatings with BNNSs and SiO2‐BNNSs were prepared on stainless steel (304) by spraying. Characterization of BNNSs and SiO2‐BNNSs by X‐ray diffraction, Fourier transform‐infrared, Raman, and scanning electron microscopy proved the success of hybridization. The surface morphology and mechanical properties were conducted to characterize the protective performance of the coating. Simultaneously, the phase composition and electrochemical properties of the coatings after high‐temperature oxidation were studied. The results showed that ceramic coatings had low surface energy with a contact angle of 102.41° when.4 wt.% SiO2‐BNNSs was added. Compared with BNNSs coating, the mechanical properties of SiO2‐BNNSs coating were significantly enhanced, the hardness of.4 wt.%SiO2‐BNNSs coating was as high as 170 HV, and the interface bonding strength was 12.24 MPa. For the oxidation corrosion resistance,.4 wt.% SiO2‐BNNSs coating under oxidation at 400°C for 50 h had the minimum corrosion current density and maximum impedance, which were.864 μA/cm2 and 177 kΩ/cm2, respectively, this indicated that SiO2‐BNNSs coating could still maintain excellent oxidation corrosion resistance under high‐temperature conditions for a long time. [ABSTRACT FROM AUTHOR]

The reliable and durable corrosion protection of commercially attractive aluminum alloys like AA2024-T3 is the subject of world-wide intensive scientific research. Thus, the quality of the preliminary treatments and the coating primers is of key importance in this field. In this aspect, Anodic Aluminum Oxides (AAO) and Cerium Conversion Coatings (CeCC) appear to be the most perspective approaches for the formation of coating primers. The present systematic study offers results of a comparative elucidation of the properties of CeCC deposited under different regimes on AAO formed on the AA2024-T3 aircraft alloy. The formation of CeCC was performed either spontaneously, or under different electrochemical regimes. The samples were subjected to analyses that included: (i) preliminary color characterization and contact angle measurements, (ii) surface observations by optical metallographic (OMM) and scanning electron (SEM) microscopy, (iii) element distribution by means of Energy dispersive X-ray (EDX) and X-ray Photoelectron (XPS) spectroscopy and (iv) corrosion tests. The latter were performed by applying Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Scanning (PDS) after 24 h of exposure to a 3.5% NaCl model corrosive medium (MCM). For completeness, the experiments were extended to 672 h of exposure for the samples with superior barrier ability. The analysis of results obtained from the employed analytical techniques has revealed that spontaneous and cathodic depositions at low current densities are suitable for formation of uniform CeCC layers. Conversely, the application of higher current densities and alternating current (AC) or anodic deposition regimes had adverse effects. [ABSTRACT FROM AUTHOR]

Constructing a superhydrophobic coating on cement-based materials' surface can effectively inhibit the invasion of external water and corrosive ions. However, current strategies of fabricating superhydrophobic coatings often require complex processes and some harmful solvents. Herein, an eco-friendly method is proposed for constructing superhydrophobic coatings on mortar surfaces to inhibit water penetration and chloride ion corrosion. The superhydrophobic coating was fabricated using superhydrophobic zeolite powders modified with nontoxic stearic acid. The mortar with superhydrophobic coating (SHC-mortar) possesses a water contact angle of 156° and water slide angle of less than 10°. In addition, the self-cleaning, waterproof and anticorrosion properties of SHC-mortar were explored. The results show that the fabricated superhydrophobic coating endows the mortar with a self-cleaning property, significantly reduces the capillary water absorption of the mortar, and improves the anticorrosion property of the mortar. [ABSTRACT FROM AUTHOR]

In recent years, the concept of pipeline intelligence, or smart pipelines, has emerged as a promising approach to address various pipeline transmission issues. Intelligent control system requires the variation and thickness of wax deposition inside the crude oil transmission pipeline to make decisions to minimize wax deposition. This study aimed to investigate wax deposition in both polyethylene (PE) and stainless steel (SS) pipes under different water contents, utilizing a custom-designed flow loop apparatus. It was found that the wax-deposit thickness on the surface of the PE test section was thicker (water content lower than 50 vol. %) and then thinner (water content higher than 50 vol. %) than that on the surface of the SS test section. The radial diffusivity and wax mass flux were calculated and proved to be responsible for the behavior variation of wax deposition. The contact angles of oil and water on the PE surface were both larger than those on the SS surface. Experimental investigation was conducted to determine the phase inversion point of oil and water emulsions, which was found to be around 50 vol.%. The results indicated that when water was the bulk phase, greater water adherence to the steel pipe wall resulted in reduced wax deposition on the SS test section. As a result, distinct deposition behaviors were observed both before and after the phase inversion point. [ABSTRACT FROM AUTHOR]

In this work, the droplet impact and rebound behaviors on a flat substrate are comprehensively investigated by using the consistent and conservative phase-field based lattice Boltzmann method, which is robust for the multiphase flow problems with the large density ratios and long-time dynamics. The dynamic behavior of the droplet considered here is governed by five key factors: the contact angle, droplet size, the Bond number, the Reynolds number and the density ratio. The effects of these parameters on the barycenter motion trajectory, contact time, the maximum spreading factor and rebound height are studied, and the results show that the Bond number and the density ratio play the critical roles in the droplet morphology when it impacts the substrate. After the impact process, there are three typical patterns: fragmentation, deposition and rebound, which are mainly controlled by the wettability, the size of droplet and the Bond number. In the rebound process, we focus on the rebound height and the number of rebound, and also give the distribution of pressure inside the droplet and the evolution of pressure before fragmentation. Finally, it is also found that under some certain conditions, the air density has a positive effect on the droplet rebound behavior and a large density ratio of 6400 can be achieved. [ABSTRACT FROM AUTHOR]

In this study cinnamaldehyde (CA) doped polyurethane cholesteryl pelargonate cholesteric liquid crystal composite membranes were produced and their properties were examined for use in biological applications. The relationship between the blood coagulation and protein adsorption was studied and the results showed that increasing CA concentration allowed an improvement in biological properties of them. Additionally, the effect of CA on the hyrophobicity of these membranes was investigated by determining water holding capacity, contact angles. The mechanical strength of these membranes were determined and it was found that their strength increased and the ability to elongate decreased with an increasing CA dopant concentration. [ABSTRACT FROM AUTHOR]