Surface Tension Components Research Articles

Some physicochemical properties of ethyl oleate mixtures with ethanol and n-hexane

Due to the wide use of ethyl oleate (EO) in agriculture, medicine and automotive fuels, measurements of the surface tension, density, viscosity and contact angle of a mixture of ethyl oleate with ethanol (ET) and/or n-hexane (HEX) were made. The contact angle was measured on polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), glass and steel. The measurement results for the mixtures of EO + ET and EO + HEX were analyzed based on the properties of individual components of the mixtures. When considering the changes in the surface tension and contact angle on PTFE for the EO + ET and EO + HEX mixtures as a function of the mixture composition there were taken into account, not only the values of the total surface tension of the mixture components, but also the components and parameters of this tension. Based on the surface tension components and parameters of EO, ET, HEX, PTFE, PMMA, glass and steel, it was possible to predict changes in the surface tension of tested mixtures and the contact angle as a function of the mixture composition.

Enhancement of the Rate of Surface Reactions by the Elastocapillary Effect.

We examined the effect of deformability of a solid substrate on the kinetics of a surface reaction that occurs between chemical species present in it and a liquid dispensed on it. In particular, we have dispensed aqueous solutions of gold and silver salt as sessile drops or as a liquid pool on a cross-linked film of poly(dimethylsiloxane) (PDMS). The PDMS surface contains organosilane (SiH), which reduces the salt, producing metallic nanoparticles at the solid-liquid interface. These experiments reveal that, for a sufficiently soft solid, the reaction proceeds about three times faster in the drop mode than in the pool mode. The reaction conditions in both cases remain exactly identical except that, for the drop, the vertical component of the liquid surface tension deforms the solid substrate at the three-phase contact line. We have estimated the solid-liquid and solid-air interfacial energy, which along with the surface energy of the liquid gives an estimate of excess free energy. This energy is found to be different for the drop and pool modes. By considering that this excess free energy decreases the activation energy barrier for the reaction, we have shown that the reaction rate constant in the drop mode should indeed exceed that in the pool mode by about three times.

Comparison of surface tension, density, viscosity and contact angle of ethyl oleate to those of ethanol and oleic acid

Taking into account extensive practical application of ethyl oleate (EO) some of its physicochemical properties were determined and compared to those of ethanol (ET) and oleic acid (OA). For this purpose the surface tension, density, viscosity and contact angle of EO, ET and OA were measured. The contact angle was measured on the polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), steel and glass in the solid–liquid–air system. Based on the results of the surface tension and contact angle of ET, EO and OA on PTFE and PMMA the Lifshitz-van der Waals component as well as electron-acceptor and electron-donor parameters of the acid-base component of surface tension of these liquids were determined. For this determination the van Oss et al. method was applied. This method was carefully analyzed in terms of its usefulness for the systems studied by us. The components and parameters of the ET, EO and OA surface tension were analyzed with regard to their molecular structure. Based on the molecular structure and on the length of bonds and contact angle between them the size of the molecules and their contactable area were determined.

Investigating mechanism of enhanced anti-fouling performance of MXene modified Janus MD membrane by XDLVO theory combined with surface elemental integration method

Organic membrane fouling is a major obstacle to the application of membrane distillation in low surface tension wastewater treatment. Membrane modification might be an effective way to mitigate membrane fouling. This study mainly explored the mechanism of enhanced anti-fouling performance of the MXene modified PVDF membrane by applying XDLVO theory combined with surface elemental integration (SEI) method. The rough membrane surfaces were first reconstructed using fractal function. Then, the interaction energy between low surface tension substances and the membranes before and after modification was calculated. The results showed that oil droplets and surfactant fouling were mainly caused by hydrophobic attraction due to Lewis acid-base (AB) interaction energy. By modifying the virgin PVDF membrane with MXene nanoparticles, the polar component of membrane surface tension (γAB) increased significantly, so that the interaction energy between all contaminants and membrane surface changed from attraction to repulsion. In addition, roughness weakened the interaction energy between contaminants and membrane surface but significantly lengthened the range of interaction distance, which together determined the ability of the membrane to attract or repel the contaminants. These findings may improve the understanding of the structure-effect relationship between membrane modification and anti-fouling ability, and provide new insights into the membrane modification for MD.

Green Solvent-Based Antifouling Polymer Brushes Demonstrate Excellent Hemocompatibility.

Medical devices are crucial for patient care, yet even the best biomaterials lead to infections and unwanted activation of blood coagulation, potentially being life-threatening. While hydrophilic polymer brushes are the best coatings to mitigate these issues, their reliance on fossil raw materials underscores the urgency of bio-based alternatives. In this work, we introduce polymer brushes of a green solvent-based monomer, prohibiting protein adsorption, bacterial colonization, and blood clot formation at the same level as fossil-based polymer brushes. The polymer brushes are composed of N,N-dimethyl lactamide acrylate (DMLA), can be polymerized in a controlled manner, and show strong hydrophilicity as determined by thermodynamic analysis of the surface tension components. The contact of various challenging protein solutions results in repellency on the poly(DMLA) brushes. Furthermore, the poly(DMLA) brushes completely prevent the adhesion and colonization of Escherichia coli. Remarkably, upon blood contact, the poly(DMLA) brushes successfully prevent the formation of a fibrin network and leukocyte adhesion on the surface. While showcasing excellent antifouling properties similar to those of N-hydroxypropyl methacrylamide (HPMA) polymer brushes as one of the best antifouling coatings, the absence of hydroxyl groups prevents activation of the complement system in blood. We envision the polymer brushes to contribute to the future of hemocompatible coatings.

Critical assessment of the correlation between surface tension components and Hansen solubility parameters

Surface or interfacial phenomena, including wetting, adsorption, adhesion, and dissolution, are of significant interest for daily life as well as for industrial and engineering applications. Surface tension and the Hansen solubility parameter (HSP) both represent similar physical characteristics related to these phenomena. It is therefore interesting to study the relation between them, and in the present work, reported empirical relations between surface tension and HSP are critically investigated. There exists an approximately proportional relation between total surface tension and HSP, although the coefficient obtained in the present work is much smaller than the commonly reported ones. The result is supported by an estimation of the coefficient using a simple physical model. On the other hand, finding correlations between the partial components of surface tension and HSP appears to be difficult as they are measured differently. The uses of databases from which measurements are taken must also be taken into question. As an example, the surface tension components of diiodomethane are investigated, and the validity of the reported values are called into question.

Identification of material parameters for the Vawter-Fung lung tissue constitutive model and assessment in human body model for impact loading

The widely used Vawter-Fung (VF) lung tissue constitutive model, originally developed to model respiration, was assessed for applicability to impact human body models (HBMs). A review of the mechanical properties of lung tissue demonstrated existing parameter sets for the VF model encompassed a wide range of stiffness relative to experimental data. Consistent experimental datasets of lung tissue for uniaxial and biaxial tension were identified, and new parameters were fit to the VF model. A thoracic pendulum impact using a contemporary HBM was used to assess existing literature parameter sets, and the new parameters. The VF model parameters presented in this study produced uniaxial and biaxial tension response with improved hyperelastic response compared to experimental data and previously reported parameters. The VF surface tension component did not contribute substantially to the lung response in impact. The proposed VF model parameters were numerically stable for impact simulations and use in HBMs.

Temperature Dependency of the Apolar Surface Tension Component for Water and Its Role in Classifying Apolar and Polar Interfacial Interactions

Temperature Dependency of the Apolar Surface Tension Component for Water and Its Role in Classifying Apolar and Polar Interfacial Interactions

Role of Membrane-Solute Affinity Interactions in Carbamazepine Rejection and Resistance to Organic Fouling by Nano-Engineered UF/PES Membranes.

In this study, polyethersulfone (PES) ultrafiltration (UF) membranes were modified with GO, Ag, ZnO, Ag-GO and ZnO-GO nanoparticles to improve carbamazepine removal and fouling prevention by making membrane surfaces more hydrophilic. The fabricated membranes were characterized for surface and cross-sectional morphology, surface roughness and zeta potential, as well as hydrophilicity, functional groups, surface tension parameters and water permeability Thereafter, the membranes were evaluated for their efficiency in removing MgSO4 and carbamazepine as well as antifouling properties. To understand the role of affinity interactions in rejection and fouling, membrane-solute adhesion energies (∆Gslm) were quantified based on the Lifshitz-van der Waals/acid-base method. Unlike previous studies, which have generalized fouling prevention to be due to improvements in hydrophilicity upon adding nanoparticles, this work further explored the role of surface tension components on rejection and fouling prevention. The addition of nanoparticles improved membrane hydrophilicity (77-62°), water permeability (11.9-17.7 Lm-2 h-1 bar-1), mechanical strength (3.46-4.11 N/mm2), carbamazepine rejection (30-85%) and fouling prevention (60-23% flux decline). Rejection and antifouling properties increased as ∆Gslm became more repulsive (i.e., less negative). Membrane modification reduced irreversible fouling, and the fouled membranes were cleaned by flushing with water. Fouling related more to membrane electron donor components (γ-), while the roles of electron acceptor (γ+) and Lifshitz-van der Waals components (γLW) were less important. This work provides more insights into the role of affinity interactions in rejection and fouling and how rejection and fouling mechanisms change with nanoparticle addition.

Polar and dispersive surface tension components of water-guanidinium chloride (Gdmcl) binary mixtures

Interfacial interaction of water with guanidinium chloride (GdmCl) is crucial to understanding protein solubility and denaturing mechanism. However, molecularly resolved parameters such as polar and dispersive surface energy components of water-GdmCl mixtures remain unknown. Here, we developed a method to determine water-GdmCl mixture surface tension and its components using four different substrates including polydimethylsiloxane (PDMS), silicone, polyethylene, and polystyrene. Results show all six combinations, PDMS-silicone, PDMS-polystyrene, PDMS-polyethylene, silicone-polyethylene, silicone-polystyrene, and polyethylene-polystyrene can estimate similar trend of total surface tension, polar and dispersive components with respect to salt concentration changes. Silicone-polyethylene pairs yield the most accurate surface tension compared to others because silicone and polyethylene have large distinctive surface energy differences. Results show that polar components increase from 51 mJ/m2 to 64 mJ/m2 when salt concentration increases; dispersive components decrease from 21 mJ/m2 to 15 mJ/m2 when salt concentration increases. Total surface tension increases from 72.8 mJ/m2 to 78.1 mJ/m2 when GdmCl increases from 0% to 40 wt%. The results of this study can elucidate molecular interaction between water and GdmCl.

Statistical evaluation of the changes in cellulose properties caused by the stepwise solvent exchange and esterification

The objective of the research was to empirically confirm the changes in cellulose reactivity caused by the pre-treatment with solvents of different polarity. Therefore, 5 solvents varying in their polar component of surface tension from 0 to 4.6 mN/m were chosen. Their impact on the biopolymer properties was carefully analysed concerning chemical structure, crystallinity and surface characteristics. It was revealed that the length of 6OH⋯O3′ intermolecular H-bonds increased upon each solvent-exchange from (0.2748 ± 0.0001) nm to approx. 0.2760 nm for non-polar solvents, hence, potentially affecting cellulose structure and availability of active centres capable of reaction. As a consequence of structural variations, dioxane- and toluene-exchanged cellulose exhibited, respectively, the lowest (around 0.6 mJ/m2) and the highest (approx. 3.1 mJ/m2) polar component of surface free energy. Therefore, these samples were esterified. Further investigation successfully confirmed expected differences. Toluene-exchanged sample exhibited degree of substitution oscillating around 20%, while dioxane-exchanged specimen – approx. 7%.

Thermodynamic Consideration of the Solid Saponin Extract Drop-Air System.

The aim of this research was to elucidate the surface active properties of Saponaria officinalis (soapwort) extract containing the plant surfactants saponins. To this end, the advancing contact angle (θ) of water, formamide and diiodomethane on the glass, as well as θ of the aqueous solution of S. officinalis extract fractions on PTFE, PMMA and glass, were studied. Based on the obtained results, the wetting behaviour of saponins was considered with regard to the surface tension components and parameters of the solutions and solids. The investigations also involved the description of the θ isotherms, the dependences between the cosine of contact angle and/or the adhesion of the solution to the solid surfaces and solution surface tension, as well as the critical surface tension of PTFE, PMMA and glass wetting. These dependences were studied based on the saponin adsorption at the different interfaces, which was deduced from the dependence between the adhesion and surface tension of the solution, as well as using the Gibbs and Frumkin isotherm equations. This proved that the saponins are poor wetting agents and that the contact angle isotherm can be described by the exponential function of the second order as well as the Szyszkowski equation, but only for PTFE.

Surface water in C-S-H: Effect of the temperature on (de)sorption

Thermal desorption is a critical process in cement-based materials subjected to temperature increase. C-S-H surface is the most likely surface available for thermal desorption in these materials. Here, we investigate surface thermal desorption in C-S-H. Molecular simulations are used to get systems equilibrated under two drained poromechanical conditions: liquid water-saturated and constant partial fluid pressure conditions. Suited fluctuation formulas are deployed to acquire properties at the adsorbed layer level. We show that thermal desorption is driven by thermal expansion of water and liquid-to-vapor phase transition (leading to cavitation). The potential energy, isochoric specific heat capacity, molar incremental enthalpy, bulk modulus, coefficient of thermal expansion, surface tension, and pressure tensor components exhibit a marked dependence on the distance from the C-S-H adsorbing surface. Parameters usually adopted in sorption models (e.g., BET family) such as monolayer thickness and adsorption energy need to be revisited using molecular scale evidence.

Langmuir-Blodgett deposition and physicochemical surface characterization of two-dimensional perovskite nanosheets on ITO-PET substrates

We successfully obtained Ca2NaNb4O13− single perovskite nanosheets by delaminating x = 4 Dion-Jacobson type KCa2NaNb4O13 layered materials. These nanosheets were then deposited onto conductive, transparent, and flexible indium tin oxide-polyethylene terephthalate (ITO-PET) substrates using the Langmuir-Blodgett (LB) technique. The polar and apolar (dispersive) surface tension components of LB nanofilms composed of Ca2NaNb4O13− perovskite nanosheets and the work of adhesion between the nanofilms and silicon and ITO-PET substrates were determined through contact angle measurements combined with mathematical modeling based on surface thermodynamics. The results showed that the apolar surface tension components had similar values for all surfaces studied, while the polar surface tension components of the nanofilms deposited on the substrates had higher values than those of the bare substrates. The higher polar interaction observed between the nanofilm and ITO-PET resulted in higher total work of adhesion of the nanofilm to the ITO-PET surface in water, while the total work of adhesion computed between the nanofilm and Si was higher in air.

Symmetric expressions of surface tension components

ABSTRACT Surface tensions of solid materials have been studied over 200 years and widely used for industrial or engineering applications. The surface tensions and surface tension components can be calculated using measured contact angles, for example, by the model studied by Owens and Wendt. The model is often represented in an asymmetric linear form, called the Owens-Wendt-Rabel-Kaelble method, with the use of the linear least squares method. However, due to the practical preference not to use many types of test liquids, the existing statistical analysis is unsuitable, especially when the data measured are scattered. The present work proposes symmetric linear and circular expressions of the model of the two surface tension components. The symmetric linear expression can be used for obtaining the polar and dispersion components of surface tension of a solid; it enables appropriate choices for test liquids, physically meaningful screening of measured values, and clear validation of deduced surface tension components of solids. The symmetric circular expressions can be applied to deduce polar and dispersion components of liquids by using test solids. In conjunction with this, appropriate choices of test solids can be determined.

A computer simulation study of extended DLVO interactions between calcite nanoparticles and real rough surfaces

The interaction energy between calcite nanoparticles and real rough surfaces in calcium carbonate supersaturated solutions was numerically calculated according to the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory and the surface element integration method. Three different surfaces, namely polished stainless steel, plasma-treated stainless steel, and fluorine-doped diamond-like carbon film, were prepared by mechanical polishing, plasma sputtering and film deposition, and characterized by atomic force microscopy. These images were then used as inputs in numerical simulations, where particle radius, solution concentration, surface electric potential, and surface tension components were varied. A total of 4052 simulations were performed. It was obtained that smaller particles interact more strongly with the surface and therefore are more attracted or repelled by the surface than larger ones. The effect of surface roughness on the particle interaction, however, depends on the physicochemical properties of the system and, therefore, a given surface may change its fouling behavior when the set of experimental conditions is changed. The effect of particle size on particle-surface interaction was found to be dependent on the relative sizes of the particle and the typical roughness features of the surface. A new local roughness metric – the minimum distance between the south pole of the particle and the rough substrate – can be used to predict the contact energy. These results may be important to engineer better antifouling surfaces for a wide range of applications, such as oil and gas exploitation and water treatment and desalination.

Effect of Boron Doping Concentration on the Wettability and Surface Free Energy of Polycrystalline Boron-Doped Diamond Film

The wettability and surface free energy of diamonds are crucial for their applications. In this study, polycrystalline boron-doped diamond (PBDD) films with different boron doping concentrations were prepared, and the effect of the boron doping concentration on the wettability and surface free energy (SFE) of the film was investigated. The SFEs of the PBDD films were investigated by employing the surface tension component approach and the equation-of-state approach. The investigation suggested that the alternative formulation of Berthelot’s rule, the Lifshitz-van der Waals/acid-base (van Oss) approach, and the Owens-Wendt-Kaelble approach were suitable for estimating the SFEs of PBDD films, whereas the Fowkes approach, Berthelot’s (geometric mean) combining rule, and Antonow’s rule could not provide reliable results. Results showed that the SFEs of PBDD films increased with increasing boron doping concentration, and the SFEs were 43.26–49.66 mJ/m2 (Owens-Wendt-Kaelble approach), 42.89–52.26 mJ/m2 (Lifshitz-van der Waals/acid-base), and 44.38–48.73 mJ/m2 (alternative formulation of Berthelot’s rule). This study also provides a reference for the application of empirical and physics-based semi-empirical approaches to SFE estimation.

Changes of Some Physicochemical Properties of Canola Oil by Adding n-Hexane and Ethanol Regarding Its Application as Diesel Fuel

Canola oil cannot be directly used as a fuel in diesel engines because its physicochemical properties differ considerably from those of diesel oil. Therefore, the studies were intended to make closer the surface tension, viscosity and density of the canola oil to those of diesel fuel by adding n-hexane and ethanol. The surface tension and its components as well as density and viscosity were determined not only for the canola oil mixtures with n-hexane and ethanol but also for the canola oil components. The surface tension components were determined based on the contact angle measurements on PTFE. To obtain the components and parameters of saturated fatty acids, the contact angles of water, diiodomethane and formamide on their layers were measured. The contact angles of the studied mixtures were also measured on the engine valve. The obtained results and theoretical considerations allowed us to explain why the values of the surface tension, density and viscosity of canola oil are higher than those for its components. They also contributed to the explanation of the mechanism of the reduction in these quantities for canola oil by the addition of n-hexane and ethanol. It appeared, for example, that viscosity of the canola oil mixture with 20% n-hexane contacted with ethanol is close to that of diesel fuel.

Evolution of Membrane Surface Properties for Membrane Distillation: A Mini Review

To date, the membrane development for membrane distillation (MD) application is growing in line with the increasing volume of various types of wastewaters discharged into environment. MD is a liquid-vapor separation process and a hydrophobic membrane is used to retain the liquid. Theoretically, the hydrophobic membrane can achieve 100% rejection of non-volatile components that dissolved in feed liquids. As a result, MD has received significant attention in water recovery from saline water as well as wastewaters. Nevertheless, in addition to the scaling problem due to salts, the hydrophobicity property of membrane becomes a concern when dealing with challenging wastewaters which contain various types of low surface tension components such as oils, grease, alcohols, organics and surfactants. The membrane pore wetting due to salts deposition fouling and low surface tension components subsequently reduces the flux and even fails the liquid-vapor separation process. This article briefly discusses the transformation of MD membrane from hydrophobic to superhydrophobic and omniphobic which purposely to enhance the flux and eliminate the membrane pore wetting.

Dependence of the Liquid Polarity in the Wetting of Rough Surface: An Effective Surface Tension Approach.

Liquid and surface polarities play an important role in wetting phenomena, and this should still be true if the surface is rough. We analyze the wetting of high-polar and low-polar liquids on rough low-polar surfaces made of polystyrene. The experimental results are analyzed by the surface tension components (STC) and the equation-of-state (EQS) approaches. Both approaches predicted a clear increase of the contact angle (CA) with the surface roughness for high-polar liquids, but they failed for low-polar liquids: STC calculations produce the wrong tendency in the total solid surface energy, and EQS is not able to fit the data for these liquids. These results show that low-polar liquids show little dependence on the roughness of a low-polar surface, while high-polar liquids are very sensitive to it. As a consequence, the calculated CAs are close to experimental values only for the high-polar liquids, while there are great differences for low-polarity liquids. Both STC and EQS approaches are able to describe the apparent CAs on polystyrene rough surfaces by using effective surface and interfacial tensions, but their effectiveness is limited to high-polarity liquids.