Temperature Dependence Of Contact Angle Research Articles

Temperature Dependence of Liquid Contact Angle at a Deformable Solid Surface

To date, it has been reliably shown by direct methods that a sessile droplet on a solid surface causes deformation of the substrate. For solids with rather low elasticity moduli, in particular, elastomers, this phenomenon becomes observable, and the deformation work reaches values sufficiently large to take it into account in the theory when necessary. Within the framework of the current theory of capillarity and the generalized Young equation, it is most convenient to introduce the deformation work (realized along and inside the three-phase contact line) into the line tension. The resultant effective line tension is several orders of magnitude higher than the usual one (for undeformable solids); therefore, it manifests itself even in macroscopic (although small) droplets. While the usual line tension is just a small correction to the classical Young equation, when elastomers are used as substrates, the effective line tension may become the main term and govern surface phenomena. In this communication, the results of work [Budziak, C.J., Varcha-Butler, E.I., and Neumann, A.W., J. Appl. Polym. Sci., 1991, vol. 42, p. 1959], which is devoted to studying the temperature dependence of liquid contact angles at elastomers, are discussed from the aforementioned points of view. The following facts have been explained: the higher the surface tension of a liquid the larger the contact angle at the same substrate; most probably, the contact angle increases with temperature; the temperature dependence of a contact angle cannot be strong because of the mutual compensation of the temperature dependences of the surface tension of a wetting liquid and the elasticity modulus of an elastomeric substrate.

Understanding the Temperature Dependence of Contact Angles of Water on a Smooth Hydrophobic Surface under Pressurized Conditions: An Experimental Study.

It is of both practical and scientific significance to understand the temperature dependence of contact angles of water on various surfaces. However, the variation trend of water wettability on a smooth hydrophobic surface with increasing temperature remains unclear. In this work, in situ characterization of the contact angle of water on Teflon (polytetrafluoroethylene) surfaces and the interfacial tension of water over a temperature spectrum from ∼25 to 160 °C under pressurized conditions (2, 3, and 5 MPa) in a nitrogen atmosphere was conducted by employing the sessile drop and pendant drop methods, respectively. A nearly invariant trend of the contact angle was observed over the entire temperature and pressure range. As expected, however, it was shown that the water-N2 interfacial tension almost linearly declines with increasing temperature and that pressure has a negative effect on the interfacial tension. Based on the theory of surface thermodynamics, the effects of temperature on the contact angles were analyzed in combination with the gas adsorption effect. Estimations on the solid-gas interfacial tension, surface entropy, and the heat of immersion were made to gain more insights into the temperature dependence of the water contact angle on a smooth hydrophobic surface.

Temperature dependence of contact angles of water on a stainless steel surface at elevated temperatures and pressures: In situ characterization and thermodynamic analysis

Phase change heat transfer (e.g., boiling of water) on surfaces can be enhanced by tuning the surface wettability, which is often quantified by the contact angle and is expected to be influenced by temperature and pressure. However, the temperature (and pressure) dependence of contact angles of water on metallic surfaces remain unclear. In this study, an in situ characterization of the contact angles of water on 304 stainless steel surfaces at temperatures from room temperature to 250 °C and at pressures up to 15 MPa was performed using the sessile drop method. It was shown that three distinct regimes can be identified on the contact angle-temperature curves. A slightly-decreasing trend of the contact angles with temperature was observed below 120 °C, followed by a steeper linear decrease at higher temperatures. A further rise of the decreasing rate with temperature was observed above 210 °C. In contrast to temperature, the pressure was shown to have little effects on the contact angles. Based on the theory of surface thermodynamics, the effects of temperature (and pressure) on the contact angles were analyzed in terms of the interfacial tensions. An empirical correlation was developed to predict the contact angles as a function of temperature.

The effect of temperature on contact angles and wetting transitions for n-alkanes on PTFE

The aim of this paper is to present a method for predicting the effect of temperature on contact angles and wetting transitions for n-alkanes on PTFE. The analysis is based on the effect of temperature on two closely related phenomena, which are critical in the determination of contact angles: intermolecular forces and the thickness of an adsorbed film in the region adjacent to the three-phase contact.Considering solely van der Waals forces, it is possible to reproduce the experimental temperature dependence of contact angles. At low temperature values, contact angles show a small and linear decrease with temperature. For higher temperature values, substantially larger decreases are exhibited by the more volatile alkanes. In the case of n-octane, a single transition from partial to total wetting is found at 443K. This transition, which arises from the vanishing of the effective Hamaker constant at 430K, is characterized by a surface specific heat exponent close to one, indicating the existence of a first order wetting transition. For the less volatile alkanes, the contact angle decrease is progressively less pronounced as the volatility decreases in such a way that for n-hexadecane the contact angle remains approximately constant throughout the temperature range under study.

Pressure and Temperature Dependence of Contact Angles for CO2/Water/Silica Systems Predicted by Molecular Dynamics Simulations

Wettability controls the capillary behavior of injected CO2, including capillary entry pressure, relative permeability, and residual fluid saturation, and it is one of the most active topics in geologic carbon sequestration (GCS). However, the large uncertainty of water contact angle (CA) data and its pressure, temperature, and salinity dependence in the literature limit our understanding on wettability. Molecular dynamics (MD) simulations have been performed to investigate the pressure (P) and temperature (T) dependence of water CAs on the silica surface. Three typical molecular surface models for silica, namely, Q2, crystalline Q3, and amorphous Q3, were selected, and simulations were conducted at wide pressure (2.8–32.6 MPa) and temperature (318–383 K) conditions. The results show that P and T dependence of water CAs on silica surfaces is controlled by surface functional groups. These findings provide new information to help with the better understanding of wettability alteration under different GCS co...

Understanding the influence of Coulomb and dispersion interactions on the wetting behavior of ionic liquids.

We study the role of dispersion and electrostatic interactions in the wetting behavior of ionic liquids on non-ionic solid substrates. We consider a simple model of an ionic liquid consisting of spherical ions that interact via Lennard-Jones and Coulomb potentials. Bulk and interfacial properties are computed for five fluids distinguished by the strength of the electrostatic interaction relative to the dispersion interaction. We employ Monte Carlo simulations and an interface-potential-based approach to calculate the liquid-vapor and substrate-fluid interfacial properties. Surface tensions for each fluid are evaluated over a range of temperatures that spans from a reduced temperature of approximately 0.6 to the critical point. Contact angles are calculated at select temperatures over a range of substrate-fluid interaction strengths that spans from the near-drying regime to the wetting regime. We observe that an increase in the relative strength of Coulombic interactions between ions leads to increasing deviation from Guggenheim's corresponding states theory. We show how this deviation is related to lower values of liquid-vapor excess entropies observed for strongly ionic fluids. Our results show that the qualitative nature of wetting behavior is significantly influenced by the competition between dispersion and electrostatic interactions. We discuss the influence of electrostatic interactions on the nature of wetting and drying transitions and corresponding states like behavior observed for contact angles. For all of the fluids studied, we observe a relatively narrow range of substrate-fluid interaction strengths wherein the contact angle is nearly independent of temperature. The influence of the ionic nature of the fluid on the temperature dependence of contact angle is also discussed.

Energetic and entropic contributions to the work of adhesion in two-component, three-phase solid–liquid–vapour systems

For one-component liquid–vapour (lv) systems Lyklema (1999) [1] has shown that the excess entropy is a rather constant quantity whereas the excess energy varies over several orders of magnitude. In this work we use literature data from two-component, three-phase solid–liquid–vapour (slv) systems to show for the first time that in these systems the majority of excess entropies of adhesion fall in a narrow range between 0.1 and 0.2mJ/m2K and show no direct relation to excess energies of adhesion. From this it is concluded that excess energy and excess entropy of adhesion are, at least in two-component, three-phase slv systems, not coupled. This finding agrees with the corresponding states principle suggested for lv systems by Lyklema [1]. Definitive conclusions are hampered by the lack of a data set with a broader range of excess energies.Geometric mean approaches relating contact angles to interface tensions are critically examined within the framework of Lyklema's [1] analysis and the insights obtained from the temperature dependence of contact angles. It turns out that none of the approaches considered can take proper account for the temperature dependence of interface tensions, which is first of all due to the neglect of entropic contributions to surface/interface tensions. At 25 °C entropic contributions make up 30–50% of the total Helmholtz free energy of adhesion.

Experiments on the contact angle of n-propanol on differently prepared silver substrates at various temperatures and implications for the properties of silver nanoparticles

In this paper we present the results of contact angle measurements between n-propanol and silver substrates in the temperature range from −10 °C to 30 °C. The interest in a potential temperature dependence of contact angles originates from recent experiments by S. Schobesberger et al. (Schobesberger S., Strange temperature dependence observed for heterogeneous nucleation of n-propanol vapor on NaCl particles. Master's thesis, University of Vienna, 2008; Schobesberger S. et al., Experiments on the temperature dependence of heterogeneous nucleation on NaCl and Ag particles. In preparation.) investigating the temperature dependence for heterogeneous nucleation of n-propanol vapour on NaCl and on silver particles. We determined dynamic advancing θ a and receding θ r angles on variously prepared silver probes. The Dynamic Wilhelmy method (Wilhelmy L., Über die Abhängigkeit der Capillaritäts-Constanten des Alkohols von Substanz und Gestalt des benetzten festen Körpers. Ann. Phys. Chem., 199:177–217, 1863) was applied using a Krüss K12 Tensiometer, with a refrigerated double-walled glass top. With respect to its potential influence on heterogeneous nucleation mainly the advancing angle is of interest. The uniform probe geometry required was achieved by accurate cutting and by multiple polishing stages up to the accomplishment of a 0.04 μm grain size. The original probes consist of 925 sterling silver including a 7.5% copper content. Additional coating with silver pro Analysi (p.A.) was applied making use of pure silver powder evaporation process via Physical Vapour Deposition (PVD). Results show that a surface contamination by copper cannot be neglected for the specification of contact angles. It turned out that additional PVD coatings not only change the values of θ a but also their temperature dependence. With increasing the number of coatings of a plate the contact angle decreases and its temperature dependence inverts. Since the contact angle hysteresis θ hyst. obtained for the variously often coated probes remained practically constant possible changes in surface roughness with increasing number of PVD layers could be excluded.

Effect of Dew Condensation on the Wettability of Rough Hydrophobic Surfaces Coated with Two Different Silanes

Dew condensation effects on the wettability of rough and smooth coatings of two fluoroalkylsilanes (FAS3 and FAS17) were investigated by controlling the temperature. Contact angles of the coatings decreased concomitantly with decreasing surface temperature. Inflection points in the temperature dependence of contact angles were observed at the dew point. They were attributable to the change of the interfacial free energy of the solid-gas interface by water adsorption. The contact angle decrease suggested a mode transition from Cassie to Wenzel on the rough surface, and resulted from the surface wettability change and the increase of the condensation amount of water. The contact angle change by increasing temperature from -6 degrees C revealed that the Wenzel mode is more stable than Cassie's mode.

The effect of temperature on capillary pressure‐saturation relationships for air‐water and perchloroethylene‐water systems

The temperature dependence of capillary pressure‐saturation relationships was measured for air‐water and perchloroethylene‐water systems in silica sand. Changes in capillary pressures, irreducible water phase saturations, and residual nonwetting saturations with temperature were determined. Relationships for temperature dependence of contact angle and interfacial tension were incorporated into the van Genuchten [1980] model and fitted to the data. Capillary pressures at constant degrees of saturation decreased as temperature increased. Hysteresis decreased, irreducible water saturations increased, and residual nonwetting saturations decreased as temperature increased. The magnitude of the change in capillary pressures could not be explained by the temperature dependence of wetting‐nonwetting interfacial tensions alone. Derived parameters for the temperature dependence of the contact angle predicted an increase of contact angle of roughly 45°–50° for air‐water and perchloroethylene systems with a temperature increase from 20° to 80°C, while literature studies suggest that contact angles should decrease with increasing temperature. It was concluded that the parametric relationship for temperature effects incorporated into the van Genuchten [1980] model fit the data well, but other effects in addition to changes in interfacial tension and contact angle played a role in the temperature dependence of capillary pressure‐saturation relationships.

Determination of solid/melt interfacial tensions and of contact angles of small particles from the critical velocity of engulfing

The critical velocity of engulfing V c of acetal, nylon-6,6, and nylon-12 particles when encountered by the solidification front of salol is reported as a function of particle size. Using the dimensional analysis derived previously, the free energy of adhesion ΔF adh for the attachment of these particles to the salol solid/melt interface is determined. These values of ΔF adh, together with the known surface tension values γ PV of the particles, are used to determine the salol solid/melt interfacial tension γ SL to be γ SL = 0.0053 ± 0.0025 erg/cm 2. Similarly, the free energies of adhesion ΔF adh for PMMA particles to the solid/melt interfaces of naphthalene, biphenyl, and salol are determined. As all the γ SL values for these systems are known—in the case of naphthalene and biphenyl from the temperature dependence of contact angles— γ PV for the PMMA particles is determined. Using the equation of state for interfaces, the contact angle for the system PMMA/water is predicted. This value is in excellent agreement with the contact angle of water on a film of PMMA obtained by solvent casting. It is concluded that measurement of the critical velocity of engulfing represents a unique method for contact angle determinations on small particles.

An investigation of the contact angles between low melting metals and substrates of niobium and zirconium

Contact angles between droplets of tin, indium and gallium and substrates of niobium and zirconium were measured for various substrate surface roughnesses over the temperature range 303 −- 923 K. Three characteristic regions of the temperature dependence of contact angles were observed. A steady-state region in which the contact angle θ is relatively independent of temperature was preceded and followed by regions in which θ decreased rapidly with increasing temperature. For the steady-state or second region, contact angles were found to be independent of time, whereas in the third region the contact angles showed a decreasing trend with increasing time at constant temperature. In accordance with theoretical predictions, when θ is greater than 90°, an increase in roughness of the substrate causes a corresponding increase in θ. Electron microprobe analyses showed that only the system Ga-Zr exhibited evidence of interdiffusion at the interface.

Interfacial properties governing ohmic contacts between gold alloys and oriented gallium arsenide crystals

Contact angles between Au-Ge and Au-Sn alloys and {111} oriented gallium arsenide crystals were determined over the temperature ranges 360 to 450° C and 280 to 400° C, respectively. Three characteristic regions of the temperature dependence of these angles were observed. At the lower temperatures, contact angles,θ, decreased sharply with increasing temperature. This region was followed by another in which the values ofθ were essentially independent ofT and finally, at the higher temperatures,θ decreased again asT increased up to the highest limit indicated above. Based on microstructural and electron microprobe analyses these observations are explained in terms of diffusional processes at the interfacial regions between the gold alloys and GaAs crystals. Furthermore, from observations of the temperature dependence of contact angles between GaAs and pure tin, it is suggested that gold plays an important role in the observed interfacial phenomena.

Temperature Dependence of Contact Angles of Water on a Low Energy Surface under Conditions of Condensation and at Reduced Pressures

SEVERAL workers have recently examined the effect of temperature on the wetting of solids and Petke and Ray1 have shown that there is extensive disagreement about both the sign and magnitude of the dependence of the contact angle with temperature. Fowkes and Harkins2 reported a temperature coefficient of +0.06 degree °C−1 for water/graphite and water/ paraffin systems whereas Adam and Elliott3 found no temperature effect when examining water droplets on solid hydrocarbons. Neumann4 showed that the contact angle of water on a polyamide increased with temperature, but Phillips and Riddiford5 reported that the contact angle of water on a siliconed glass surface was essentially constant for a temperature range of 70° C. Sutula et al.6 gave a temperature coefficient of + 0.03 degree °C−1 for water on a fluoropolymer, but Padday7 suggested coefficients of − 0.15 degree °C−1 and +0.55 degree °C−1 for advancing and receding contact angles on paraffin wax at temperatures of 20° C to 40° C. Petke and Ray1 themselves showed that advancing contact angles for water on a series of low surface energy polymers were all negative (−0.04 degree °C−1 to −0.14 degree °C−1) and that the receding contact angles could take positive or negative values (−0.04 degree °C−1 to +0.06 degree °C−1). For a ‘Teflon’ surface Neumann8 observed no variation of contact angle from room temperature to 60° C for water at atmospheric pressure, although coefficients of −0.3 degree °C−1 and −0.15 degree °C−1 were reported for the systems butyl chloride and n-heptane and butyl alcohol. Phillips and Riddiford9 also quoted contact angle invariance with temperature within the range 0° to 60° C for the ‘Teflon’–water system at a pressure of 1 atmosphere.

The temperature dependence of contact angles polytetrafluoroethylene/ N-alkanes

Measurements of the temperature dependence of contact angles of long-chained alkanes from decane to hexadecane are reported in the temperature range from 25°C to 70°C. Solid surface tensions and surface entropies are estimated. Heats of wetting calculated from these data are compared with calorimetric heats of immersion.

Temperature dependence of contact angles of liquids on polymeric solids

Contact angles of water, glycerol, formamide, ethylene glycol, 1-bromonaphthalene, and bromobenzene were measured in the temperature range 5–160° on surfaces of polyethylene, polystyrene, polyacetal, polycarbonate, poly(ethylene terephthalate), and poly(tetrafluoroethylene-co-hexafluoropropylene). Stable advancing and receding angles were found and these varied linearly with temperature except in the range where solubility or swelling was evidence. Superheated water wet all the polymers to a greater degree than predicted. For the fluoropolymer all the liquids showed a negative temperature coefficient of the contact angle, both advancing and receding, ranging from 0.03 to 0.1 deg/°C. For the other polymers coefficients for advancing angles were nearly all negative and ranged from 0.03 to 0.18 but most receding angle values were positive; several liquid-polymer pairs showed a negligible coefficient. Temperature coefficients of the critical surface tension and of the dispersion surface tension of each solid were evaluated. Correlations of these derived quantities are discussed.

Temperature dependence of contact angle and of interfacial free energies in the naphthalene-water-air system. Reply

Temperature dependence of contact angle and of interfacial free energies in the naphthalene-water-air system. Reply

Temperature dependence of contact angle and of interfacial free energies in the naphthalene-water-air system. Comments

Temperature dependence of contact angle and of interfacial free energies in the naphthalene-water-air system. Comments

Temperature dependence of contact angle and of interfacial free energies in the naphthalene-water-air system

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTemperature dependence of contact angle and of interfacial free energies in the naphthalene-water-air systemJohn Barrie Jones and Arthur W. AdamsonCite this: J. Phys. Chem. 1968, 72, 2, 646–650Publication Date (Print):February 1, 1968Publication History Published online1 May 2002Published inissue 1 February 1968https://doi.org/10.1021/j100848a044RIGHTS & PERMISSIONSArticle Views741Altmetric-Citations36LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (586 KB) Get e-Alerts