Surface Wetting Properties Research Articles

Surface tension, wettability and tribological properties of a low viscosity oil using CaCO3 and CeF3 nanoparticles as additives

The rise of the electric vehicles as a more sustainable transport alternative makes it necessary to study new transmission fluids that adapt to their needs and improve their efficiency. The thermophysical properties (contact angle, surface tension and rheology) and tribological properties (friction and wear) of potential PAO8 transmission nanofluids using CaCO3 and CeF3 nanoparticles as additives are evaluated at mass concentrations of 0.05, 0.10, 0.15 and 0.20 wt%. Low contact angle and surface tension values are obtained, indicating good wettability. When the nanoparticles are used as PAO8 additives, small reductions in surface tension are achieved, but no differences in contact angle are observed. All nanolubricants and base oil exhibit Newtonian behavior. Concerning the tribological behavior, reductions in the friction coefficient are achieved for both types of nanoparticles, with the largest reductions comparing to PAO8 base oil being 13 % and 10 % for nanolubricants containing 0.05 wt% CaCO3 and 0.10 wt% CeF3 nanoparticles (NPs), respectively. In terms of antiwear performance, maximum reductions are obtained for the CaCO3 nanolubricant of 28 % (0.15 wt%), 41 % (0.10 wt%) and 59 % (0.15 wt%) and for the CeF3 nanolubricant of 19 % (0.20 wt%), 53 % (0.10 wt%) and 58 % (0.20 wt%) for the parameters of diameter, depth, and area of the worn track, respectively. Through Raman microscopy, the tribological mechanisms of tribofilm formation, repairing, and rolling can be proposed. A discontinuous tribofilm formed by the CaCO3 and CeF3 nanoparticles reduces the contact area between the two surfaces protecting them.

Evaluation of Pressure, Surface Characteristics, and Fluid Properties Effect on Pool Boiling Heat Transfer Over Plain and External Micro-Finned Cylindrical Surfaces

Abstract Pool boiling is extensively used in high- and low-temperature heat exchangers as it results in a high heat transfer coefficient compared to natural and single-phase forced convection. Pool boiling experimental study conducted over a plain cylindrical surface (PS) and four external micro-finned cylindrical surfaces (MFCSs), with R123 and R141b at different pressures in the heat flux range 20–100 kW/m2, is presented in this paper. The objective of the present study is to explore the effect of pressure, surface characteristics, and fluid properties on pool boiling heat transfer over plain and micro-finned cylindrical surfaces. The boiling performance improved at a higher pressure, irrespective of the working fluid used for all the test surfaces. It was found that, with the rise in pressure, the boiling heat transfer coefficient (BHTC) for the MFCSs increases at a higher rate than the PS. In comparison with PS, the average rise in the BHTC with pressure, for the MFCS-1, MFCS-2, MFCS-3, and MFCS-4 with R123 were 69.3% to 84.3%, 3.3% to 9.9%, 16.9% to 22.4%, and 29.4% to 40.2%, respectively. The higher BHTC over micro-finned cylindrical surfaces results due to more nucleation site results from lower surface wettability and micro-finned geometry. It was observed that the pool boiling over the plain surface with R123 results in higher BHTC compared with R141b at all tested pressures, whereas the pool boiling characteristics over MFCSs varied based on the combined effect of micro-finned surface geometry, surface wettability, heat flux, pressure and fluid properties. The bubble departure diameters over all the surfaces were measured at 30 W, 60 W, and 90 W at different pressures, and a new model of bubble departure diameter was proposed based on dimensionless terms. The total mean absolute error (MAE) of the proposed bubble departure diameter model was about 6.79% for the whole range of data points.

Hydrophobic Nano-Microcapsules Effectively Improve the Waterproof Performance of Coatings

Due to the special surface wettability, self-cleaning, drag reduction, anti-icing and other properties, superhydrophobic materials are widely used as coating or coating additive on the surface of building materials, ships, and even for liquid transportation, biomedicine, etc., which have become one of the research hotspots in the direction of coating in recent years. However, the hydrophobic surface itself has weak stability and poor durability, which affects its application value. Therefore, in this study, PS nano-microcapsule was prepared by the multiphase emulsion method, and their particle size was measured by SEM electron microscopy to be about 350–550 nm, with a relatively uniform distribution. The hydrophobicity of PS nano-microcapsule modified with trimethoxy (1H, 1H, 2H, 2H-trifluoroctyl) silane (PFOTMS) at different molar ratios was investigated. SEM results showed that the surface roughness of the modified PFOTMS-PS nano-microcapsule could be changed. The contact angle proved that the greater the content of PFOTMS, the better the hydrophobicity of the modified PFOTMS-PS nano-microcapsule. When the content reached 50%, the hydrophobic performance was the best. As a coating, PFOTMS-PS nano-microcapsule has no specific requirement for the properties of the substrate material. It should be noted that the hydrophobicity of the coating did not change significantly after 30 days at room temperature. The above results indicated that PFOTMS-PS nano-microcapsule had good hydrophobicity and stability, and is expected to be used in many fields such as waterproof textiles and architectural coatings in the future.

A hybrid substrate for practical applications in dropwise condensation enhancement

We introduce a durable hybrid substrate consisting of superhydrophilic micropillars surrounded by superhydrophobic depressions for practical industrial applications. The proposed surface can be mass-produced via a facile and affordable method. Moreover, the stability tests show that the wettability properties of fabricated surfaces do not vary after the imposition of hot steam flow for 110 h. Two hybrid samples with different patterns of micropillars are compared with superhydrophobic and bare aluminum samples to explore the physics behind the condensation improvement ability of hybrid surfaces. The results reveal that the heat transfer coefficient and heat flux can be significantly increased with the incorporation of micropillars with optimized dimensions. Among the tested surfaces, the hybrid one, whose pillar's diameters are 500 μm, increases the heat transfer coefficient by 33.50% and 19.60% with respect to the superhydrophobic and bare surfaces, respectively, at a subcooling temperature of 18.50 °C.

CORROSION BEHAVIOR AND WETTING PROPERTIES OF CAST TNZT ALLOYS

Five experimental alloys Ti-9Nb-8Zr-xTa-2Ag (x = 0, 5, 10, 15) were obtained and analyzed in the as-cast condition. The microstructure, corrosion behavior and surface free energy on the samples polished and corroded in artificial saliva were investigated. The microstructure is comprised of a mixture of α and β phase and the proportion of β phase increases with tantalum content increase. At 10 % Ta a drastic change in the microstructure was observed that severely altered the corrosion behavior, as the corrosion rate increased significantly beyond this point. The alloys are hydrophilic and corrosion tends to increase the surface free energy of the alloy with 15 % Ta that was mostly affected by the corrosion. The tantalum content increase affects directly the microstructure and indirectly the corrosion and surface wetting properties of the experimental alloys.
 Tantalum content increase affects directly the microstructure and indirectly the corrosion and surface wetting properties of the experimental alloys.

Experimental investigation of wettability alteration of oil-wet carbonate surfaces using engineered polymer solutions: The effect of potential determining ions ([Mg2+/ SO42−], and [Ca2+/ SO42−] ratios)

Engineered water polymer flooding (EWPF) is a promising method to improve oil recovery in carbonate reservoirs holding more than half of the world's oil reserves. It involves combining engineered water (EW) and polymer flooding (PF) to modify rock wettability, reduce mobility ratio, promote polymer stability, and lower required polymer concentration. However, limited studies addressed the simultaneous effect of engineered water compositions (i.e. potential determining ions (PDIs)) on the viscosity of polymer and wettability alteration of various carbonate surfaces. Accordingly, this study aimed to investigate the effect of salinity, PDIs, and polymer functional groups (partially hydrolyzed polyacrylamide (HPAM), and acrylamide tertiary butyl sulfonic acid (ATBs)) on the wetting properties of calcite, chalk, and dolomite surfaces as well as the viscosity of solutions at static conditions. The experimental protocol included viscosity, contact angle (CA), pH, and static adsorption tests. Two combinations of PDIs were considered in the study: [Mg2+/SO42−], and [Ca2+/SO42−]. The results revealed that the polymer becomes more tolerant to the salinity as the sulfonation degree increases, given the same molecular weight. However, at a polymer concentration of 5000 ppm, the HPAM polymer showed higher viscosity than the ATBs-based polymers, as the formation brine (FB) was diluted to 100 folds (100DFB). The tendency of shifting the wettability of carbonate surfaces towards a more water-wet state using EW and EWP treatment solutions decreased in the following order: Chalk ≥ Calcite˃ Dolomite. The study also indicates that, the wettability alteration towards favorable condition is dependent on the initial wettability of the carbonate surface. The higher level of oil-wetness detected in aged dolomite, compared with calcite and chalk, resulted in less effectiveness of EWP for dolomites. However, the low polymer interaction with dolomite surfaces indicates a positive impact on reducing polymer consumption. Moreover, the HPAM polymer was more effective in altering the wettability of dolomite towards a water-wet state compared to the ATBs-based polymer. The overall results indicate that ATBs-based polymer is a potential candidate for optimizing the effectiveness of EWPF in carbonates.

Influence of surface fluorination on surface wetting property of epoxy resin and its mechanism

The hydrophilic surface of epoxy resin (EP) after surface fluorination was a mystery and confused scholars for a long time. To reveal the underlying mechanism of fluorination enhancing surface affinity to water, the fluorinated EP was constructed, and the surface wetting property and chemistry was studied by experiment. Meanwhile, the molecular dynamics calculation was conducted and the hydrophilic groups in EP and fluorinated EP was clarified. It was found that only O-C = O was the hydrophilic group for EP, while for fluorinated EP, these were OCO, CF and CF2. The fluorination introduced CF and CF2 groups contributed to an enhanced affinity of EP surface to water and led to a hydrophilic surface of epoxy resin after surface fluorination.

Yeşil Kimya İle Fotokürlenebilen Fosfor İçerikli Pamuk Kumaş Kaplamalari

In this work, a bio-based, lightweight, coated cotton fabric by using a cleaner manufacturing method, “photocuring” was proposed in order to be used as an alternative to the conventional heat-, solvent-, and water-based outdoor textile (tarpaulin, tent, etc.) manufacturing. For this purpose, photocurable bio-based phosphorylated oligomer was synthesized with the reaction between a monomethacrylate functional phosphorus containing monomer and epoxidized soybean oil (ESBO). The synthesized phosphorylated ESBO (P-ESBO) oligomer was used in cotton fabric coatings in different proportions and photocured with UV light exposure. The effects of the amount of P-ESBO oligomer in the formulation on the crystalline morphology, mechanical, thermal, surface wettability, flammability, and abrasion resistance properties of the cotton fabrics were all searched. It was revealed that the increasing amount of P-ESBO oligomer in the formulation increases the drapeability and tensile strength of the fabrics with enhanced flame resist property by giving higher char yields. Besides, phosphorylated oligomer also acted as an adhesion promoter between the fabric surface and coating layer resulting a better abrasion resistance property.

Effect of the Chemical Composition of Coals on Surface Wettability and Filtration Properties

The method of liquid filtration through a layer of coal powder was used for a comprehensive characterization of surface wettability in conjunction with the determination of the contact angle. The effect of the degree of chemical maturity (metamorphism) of coal on the filtration characteristics of a layer with fractured porous properties was evaluated. Different activity of coal surfaces to water wettability upon a change from the native state to the surface-oxidized one was established. It was shown that the wetting and filtration properties of the coal surfaces increased from native to surface-oxidized coals and decreased as the degree of metamorphism increased from low to medium metamorphosed coals.

Introducing a graphical user interface for dynamic contact angle determination

Contact angle goniometry is an important characterization technique that can determine crucial information, such as the wettability, interfacial tension, and adhesion properties of solid and liquid surfaces alike. However, while this technique is already widespread, the by-hand analysis process of elucidating the advancing and receding contact angles (ARCAs) from the actual data set has many pitfalls and is fraught with human error. In this article, we introduce a graphical user interface (GUI) called ARCA Finder that drastically simplifies the analysis process by displaying the contact angle data in a novel perspective and aiding the user to determine the most accurate measurement from the available data based on the full definition of the dynamic contact angles. The goal of this invention is to improve measurement accuracy by reducing human error in goniometry, while also improving the repeatability of measurements among different researchers. By testing this approach alongside by-hand analysis on both synthetic and real dynamic contact angle videos, our results demonstrate a noticeable difference in the measured values, which suggests that the ARCA Finder GUI improves the measurement accuracy compared to the standard approach.

Engineering push–pull structural versatility in highly functional carbazole-based hole transporting materials design for efficient perovskites solar devices

This study proposes a push–pull molecular engineering strategy to design highly functional hole transport materials (HTMs) for perovskite solar cells (PSCs). The strategy involves introducing acceptor-anchor groups via benzene spacer to the versatile carbazole core containing dimethoxytriphenylamine side groups, resulting in a series of nine newly designed HTM moieties (BEN-A1 to BEN-A9). Quantum simulation protocols using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods were employed to investigate the designed HTMs. Our results demonstrate that the designed HTMs exhibit promising charge separation and transport throughout the molecule with lower spatial hole-electron overlap at the carbazole core, resulting in 98% intrinsic charge transfer and small exciton binding energy (0.003–0.108 eV). The HTMs also exhibit stabilized HOMO energy levels (by up to 0.13 eV) approaching the threshold (−5.38 eV) with appropriate HTM/Perovskite energy levels alignment, suggesting excellent charge extraction and higher VOC. Optical analysis shows that our proposed HTMs exhibit large stokes shift values (82–108 nm) and transparent absorption in broader visible region, enabling full utilization of light for perovskite layer for photocurrent generation, efficient energy conversion, reduced thermalization losses, and improved spectral selectivity. The HTMs exhibit smaller hole reorganization energy (0.111–0.137 eV) and higher transfer integral, indicating robust hole mobility owing to enhanced carbazole core functionality. Furthermore, higher negative solvation-free energy values (−16.19 to −20.89 kcal/mol) and elevated dipole moments imply better solubility and surface-wetting properties. Overall, this study broadens our understanding of push–pull molecular engineering for versatile carbazole-based HTMs, which have immense prospects for efficient and functional application in PSCs.

Evaluating The Effect Of Propolis On Surface Roughness And Wettability Properties Of The Addition Silicon Impression Material

Abstract : Dental impression materials should always be disinfected after contact with a patient's blood, plaque or saliva to prevent contamination from spreading. The disinfectants could have an effect on the surface roughness and wettability properties. The purpose of this study was to investigate the effect on the surface roughness and wettability properties of addition silicon impression material after immersion in two disinfectants (5.25% NaOCL for 10 min and 16 mg/ml propolis for 5,10, and 15 min). 50 heavy- and light-body addition impression materials specimens were randomly divided into test groups of five specimens for each test. The impression specimens were immersed into two disinfection solutions: 5.25% NaOCL for 10 min and 16 mg/ml propolis for 5,10,15 min but the control group received no treatment. A digital Profilometer was used to measure surface roughness while a Goniometer was used to measure the contact angle which was used to estimate the specimens' wettability. Accordingly, the study has s found that there was no statistically significant difference between the addition silicon imprint material's wettability and the surface roughness (P>0.05) when compared to the control group. The immersion in 16% propolis for 10 minutes shows no significant effect on the addition's wettability or surface roughness.

Polyvinyl chloride (PVC)/ Halloysite (HNT) nanocomposites: Thermal stability and structural characterization studies

Due to its versatile properties polyvinyl chloride (PVC) based materials are employed in several applications. At high temperatures and in acidic media PVC is prone to release toxic materials into the environment. Several reports are available in the literature about the modification of PVC to minimize such problems. Herein, an attempt is made to prepare PVC/Halloysite nanotube (HNT) nanocomposites with a fixed amount of compatibilizer, OPTIM GE 344 (maleic anhydride modified very low-density polyethylene (VLDPE)) and characterize the composites with respect to thermal stability, mechanical properties, and structural aspects. Both tensile and flexural strength showed appreciable improvement for the 4 wt% loading of the nanofiller. Thermogravimetric analysis (TGA) showed that the maximum degradation temperature improved by approximately 24 °C for 4 wt% filled composites. PVC thermomat measurements of the samples were used to study the thermal stability of the composites. PVC without HNT showed 36 min as the stability time and it increased to 398 min for 4 wt% of HNT loading. To complement the thermal properties of the composites, the mass loss measurement and contact angle behavior of the composite surfaces were also done. The decrease in contact angle values denoted better surface wettability properties. The mass loss measurements showed a decrease with respect to the filler loading of HNT, indicating a better interaction between the polymer matrix and HNT.

Tensile and Surface Wettability Properties of the Solvent Cast Cellulose Fatty Acid Ester Films.

Thermoplastic cellulose esters are promising materials for bioplastic packaging. For that usage, it is important to understand their mechanical and surface wettability properties. In this study, a series of cellulose esters are prepared, such as laurate, myristate, palmitate, and stearate. The aim of the study is to investigate the tensile and surface wettability properties of the synthesized cellulose fatty acid esters to understand their suitability as a bioplastic packaging material. Cellulose fatty acid esters are first synthesized from microcrystalline cellulose (MCC), then dissolved in pyridine solution, and after the solvent cast into thin films. The cellulose fatty acid ester acylation process is characterized by the FTIR method. Cellulose esters hydrophobicity is evaluated with contact angle measurements. The mechanical properties of the films are tested with the tensile test. For all the synthesized films, FTIR provides clear evidence of acylation by showing the presence of characteristic peaks. Films' mechanical properties are comparable to those of generally used plastics such as LDPE and HDPE. Furthermore, it appears that with an increase in the side-chain length, the water barrier properties showed improvement. These results show that they could potentially be suitable materials for films and packaging materials.

Enhancement of Dropwise Condensation Heat Transfer through a Sprayable Superhydrophobic Coating.

Improving the shedding rate of condensed droplets has many applications in industries and daily problems, including increasing heat transfer and self-cleaning properties. One way to achieve this goal is by enhancement of the wetting properties of surfaces. In this research, the hierarchical superhydrophobic coating over aluminum has been applied using a relatively cost-effective method, spraying, which is also applicable to any metal surface used as a condenser. According to the results obtained from the experimental tests, the fabricated surface is highly superhydrophobic, with a contact angle of 158° and contact angle hysteresis of less than 5°. The results show that the presented surface increases the heat transfer coefficient by 20.6% at the subcooling temperature of 25.5 °C when the surface temperature and relative humidity are 70 °C and 98%, respectively. In addition, this coated surface showed great potential at lower surface temperatures by increasing the water condensation rate as much as 50.5% at the subcooling temperature of 12 °C, when the surface temperature and relative humidity are 11.25 °C and 70%, respectively. Therefore, it is found that for the fabricated superhydrophobic paint in the present study, the effectiveness of the dropwise condensation mode profoundly depends on surface temperatures besides subcooling temperatures. In other words, a surface with lower temperatures shows better performance for the same subcooling temperatures. In addition, various types of durability tests are carried out. The results reveal that this coating has good durability against high surface temperatures, submerged conditions for 30 days, imposing hot steam for 150 h, corrosion, and organic solvents. Hence, it is suitable for industrial applications.

Biomimetic surfaces: Insights on the role of surface topography and wetting properties in bacterial attachment and biofilm formation

The study explores the impact of biomimetic surfaces on bacterial attachment and biofilm formation. Specifically, it investigates the effects of topographic scale and wetting behavior on the attachment and growth of Staphylococcus aureus and Escherichia coli on four different biomimetic surfaces: rose petals, Paragrass leaves, shark skin, and goose feathers. Using soft lithography, epoxy replicas with surface topographies similar to those of the natural surfaces were created. The static water contact angles of the replicas exceeded the hydrophobic threshold of 90°, while the hysteresis angles were found to be in the order of goose feathers, shark skin, Paragrass leaves, and rose petals. The results showed that bacterial attachment and biofilm formation were the lowest on rose petals and the highest on goose feathers, regardless of the bacterial strain. Additionally, the study revealed that surface topography had a significant impact on biofilm formation, with smaller feature sizes inhibiting biofilm formation. Hysteresis angle, rather than static water contact angle, was identified as a critical factor to consider when evaluating bacterial attachment behavior. These unique insights have the potential to lead to the development of more effective biomimetic surfaces for the prevention and eradication of biofilms, ultimately improving human health and safety.

Effect of the Chemical Composition of Coals on Surface Wettability and Filtration Properties

Effect of the Chemical Composition of Coals on Surface Wettability and Filtration Properties

Friction force-based measurements for simultaneous determination of the wetting properties and stability of superhydrophobic surfaces

HypothesisContact angle and sliding angle measurements are widely used to characterize superhydrophobic surfaces because of the simplicity and accessibility of the technique. We hypothesize that dynamic friction measurements, with increasing pre-loads, between a water drop and a superhydrophobic surface is more accurate because this technique is less influenced by local surface inhomogeneities and temporal surface changes. ExperimentsA water drop, held by a ring probe which is connected to a dual-axis force sensor, is sheared against a superhydrophobic surface while maintaining a constant preload. From this force-based technique, static and kinetic friction forces measurements are used to characterize the wetting properties of the superhydrophobic surfaces. Furthermore, by applying increased pre-loads to the water drop while shearing, the critical load at which the drop transitions from the Cassie-Baxter to Wenzel state is also measured. FindingsThe force-based technique predicts sliding angles with reduced standard deviations (between 56 and 64%) compared to conventional optical-based measurements. Kinetic friction force measurements show a higher accuracy (between 35 and 80%) compared to static friction force measurements in characterizing the wetting properties of superhydrophobic surfaces. The critical loads for the Cassie-Baxter to Wenzel state transition allows for stability characterization between seemingly similar superhydrophobic surfaces.

Effects of plasma treatments on the surface wettability properties of PTFE polymeric films

A cold cathode plasma source is constructed for modifying PTFE surface characteristics. The source was easily built, had a consistent plasma discharge medium and acceleration system. A cylindrical Langmuir probe is also used to evaluate plasma parameters like density, temperature or even plasma potential. This probe is designed to be moveable so that it may approach any desired position in the plasma volume. The influences of nitrogen pressure and probe-cathode gap on plasma parameters were investigated. The electron temperature [Formula: see text] fluctuated from [Formula: see text] to [Formula: see text][Formula: see text]eV as the pressure rises from 0.2 to 0.4[Formula: see text]mbar. Further, by increasing the cathode-probe gap from 0.4 to 2[Formula: see text]cm, the electron densities increased from [Formula: see text][Formula: see text]cm[Formula: see text] to [Formula: see text][Formula: see text]cm[Formula: see text]. Furthermore, the contact angles, work of adhesion and surface free-energy of pristine as well as irradiated PTFE films, were estimated. The results demonstrated that by extending the plasma exposure duration from 0 to 12[Formula: see text]min, the water contact angle is lowered from 82.2∘ to 30.5∘. At these conditions, the work of adhesion is raised from 81.9 to 134.1[Formula: see text]mJ/m2, as the surface free energy is increased from 29.8 to 71.8[Formula: see text]mJ/m2.

Effect of electrolyte composition on the surface characteristics of plasma electrolytic oxidation coatings over Ti[sbnd]40Nb alloy

The present work aims to develop corrosion-resistant and cytocompatible coatings on Ti40Nb alloy by the plasma electrolytic oxidation (PEO) process. Usually, PEO coatings on niobium substrate with superior surface characteristics are obtained using a silicate-based electrolyte system, and a phosphate-based electrolyte system is used for titanium substrate. Till date, electrolyte system composition is not optimised for the PEO coatings on Ti40Nb alloys. To study the influence of electrolyte composition on PEO coating properties over Ti40Nb alloy, three different concentrations of phosphate and silicate (75:25, 50:50, and 25:75) and a fixed amount of KOH were used, and their surface characteristics and corrosion properties were evaluated in this study. We found that coatings formed with an equal proportion of phosphate and silicate in an electrolyte system are dense, compact, thick and corrosion-resistant. A coating aimed for high bioactivity is also developed by adding hydroxyapatite (HA) nanoparticles to an equal proportion (50:50) electrolyte system. After the successful development of the PEO coatings over Ti40Nb alloy, its phase composition, surface morphological features, wettability, scratch resistance, and corrosion properties are examined. The cell viability and live/dead cell morphology of L-929 fibroblast cells were evaluated for untreated Ti40Nb alloy, PEO-treated Ti40Nb alloy, and Ti40Nb alloy PEO-treated with hydroxyapatite nanoparticles. All surface-modified samples exhibited better corrosion resistance than the untreated alloy. Ti40Nb alloy PEO treated with phosphate: silicate electrolyte system (50:50) exhibited better scratch resistance, higher wettability, bioactivity, favourable chemical composition, and surface morphological features than the other ratios of phosphate and silicate (25:75 and 75:25). Meanwhile, Ti40Nb alloy PEO treated with hydroxyapatite nanoparticles addition showed better cytocompatibility than without HA addition.