Experimental Observation of Critical Wetting

Ragil, K.; Meunier, Jacques; Broseta, Daniel; Indekeu, Joseph; Bonn, Daniel

doi:10.1103/physrevlett.77.1532

Cited by 184 publications

(162 citation statements)

References 18 publications

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“…Wetting and interfacial phenomena are dominated by the rich interplay between intermolecular forces and the fluctuation effects associated with thermal noise and interfacial capillary waves [8][9][10][11][12]. These lead to a very rich picture of possible surface phase behaviour occurring over different length-scales, that call for cross-disciplinary fundamental investigations.…”

Section: Introductionmentioning

confidence: 99%

Classical density functional study of wetting transitions on nanopatterned surfaces

Yatsyshin

Parry

Rascón

et al. 2017

J. Phys.: Condens. Matter

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Abstract.Even simple fluids on simple substrates can exhibit very rich surface phase behaviour. To illustrate this, we consider fluid adsorption on a planar wall chemically patterned with a deep stripe of a different material. In this system, two phase transitions compete: unbending and pre-wetting. Using microscopic density-functional theory, we show that, for thin stripes, the lines of these two phase transitions may merge, leading to a new two-dimensional-like wetting transition occurring along the walls. The influence of intermolecular forces and interfacial fluctuations on this phase transition and at complete pre-wetting are considered in detail.

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Section: Introductionmentioning

confidence: 99%

Classical density functional study of wetting transitions on nanopatterned surfaces

Yatsyshin

Parry

Rascón

et al. 2017

J. Phys.: Condens. Matter

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“…Figure 1 shows the calculated first-order and critical transition temperatures for pentane and hexane, respectively, on brine in the concentration range 0 ≤ c NaCl ≤ 2.5 mol/L. The experimental points for the respective transition temperatures for hexane on brine [1] and for pentane on water [4,2] by open symbols. The overall agreement is very good, indicating that the theory incorporates the most important effects that lead to sequential wetting even quantitatively.…”

Section: Resultsmentioning

confidence: 99%

Transition temperatures and contact angles in the sequential-wetting scenario of n-alkanes on (salt) water

Weiß

Indekeu

2004

Fluid Phase Equilibria

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Alkanes of medium chain length show an unusual wetting behavior on (salt) water, exhibiting a sequence of two changes in the wetting state. When deposited on the water surface at low temperatures, the liquid alkane forms discrete droplets that are interconnected only by a molecularly thin film. On increase of the temperature, there occurs a sudden jump of the film thickness and, at this first-order transition, a mesoscopically thick layer of liquid alkane is formed. Heating the system further leads to a divergence of the film thickness in a continuous manner. While the long-range forces between substrate and adsorbate are responsible for the critical transition, which occurs at the temperature at which the Hamaker constant changes sign, it is primarily the short-range components of the forces that bring about the first-order transition. We calculate the Hamaker constant of the system and show how, within a modified Cahn theory, accurate predictions of the first-order transition temperatures can be obtained for n-alkanes (pentane and hexane) on water and even on brine. Furthermore, we study the variation of the contact angle as a function of temperature.

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“…As in several previous works on the wetting properties of alkanes (on aqueous substrates), 17,23,22,26 we employ the Peng-Robinson equation of state to describe the thermophysical bulk properties of hexane. 38 According to this equation of state, the pressure is given by:…”

Section: A Equation Of State For Hexanementioning

confidence: 99%

“…8,11 While short-range critical wetting has been seen very recently in methanol/nnonane mixtures, 16 the first experimental observation of critical wetting was for an example of the long-range type: Ragil et al reported a continuous divergence of the film thickness for pentane on water. 17 From the effective exponent of −1 that describes this divergence (see above) and the fact that the location of the transition (53 • C) coincides with the temperature at which the Hamaker constant changes sign, it was concluded that long-range forces bring about the critical transition. 17 In accord with this assumption is the considerable distance of the critical wetting temperature from any bulk critical point.…”

Section: Introductionmentioning

confidence: 99%

“…17 From the effective exponent of −1 that describes this divergence (see above) and the fact that the location of the transition (53 • C) coincides with the temperature at which the Hamaker constant changes sign, it was concluded that long-range forces bring about the critical transition. 17 In accord with this assumption is the considerable distance of the critical wetting temperature from any bulk critical point.…”

Section: Introductionmentioning

confidence: 99%

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Effect of ion hydration on the first-order transition in the sequential wetting of hexane on brine

Weiß

Indekeu

2003

The Journal of Chemical Physics

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In recent experiments, a sequence of changes in the wetting state ('wetting transitions') has been observed upon increasing the temperature in systems consisting of pentane on pure water and of hexane on brine. In this sequentialwetting scenario, there occurs a first-order transition from a partial-wetting state, in which only a microscopically thin film of adsorbate is present on the substrate, to a 'frustrated complete wetting state' characterized by a mesoscopically, but not yet macroscopically thick wetting film. At higher temperatures, one observes a continuous divergence of the film thickness and finally, at the critical-wetting temperature, the complete-wetting state, featuring a macroscopic film thickness, is reached. This sequence of two transitions is brought about by an interplay of short-range and long-range interactions between substrate and adsorbate. The critical wetting transition is controlled by the longrange forces and is, thus, found by determining where the Hamaker constant, as calculated from a Dzyaloshinskii-Lifshitz-Pitaevskii-type theory, changes sign. The first-order transition involves both short-range and long-range forces and is, therefore, more difficult to locate. While the pentane/water system is well understood in this respect by now, a detailed theoretical description of the hexane/brine system is hampered by the a priori unknown modification of the interactions between substrate and adsorbate upon the addition of salt. In this work, we argue that the short-range interaction (contact energy) between hexane and pure water remains unchanged due to the formation of a depletion layer (a thin 'layer' of pure water which is completely devoid of ions) at the surface of the electrolyte and that the presence of the salt manifests itself only in * E-mail: volker.weiss@fys.kuleuven.ac.be 1 a modification of the long-range interaction between substrate and adsorbate. In a five-layer calculation considering brine, water, the first layer of adsorbed hexane molecules, liquid hexane, and vapor, we determine the new long-range interaction of brine with the adsorbate across the water 'layer'. According to the recent theory of the excess surface tension of an electrolyte by Levin and Flores-Mena, this water 'layer' is of constant, i.e. salt-concentration independent, thickness δ, with δ being the hydrodynamic radius of the ions in water. Once this radius has been determined, the first-order transition temperatures can be calculated from the dielectric properties of the five media. Our results for these temperatures are in good agreement with the experimental ones.

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Experimental Observation of Critical Wetting

Cited by 184 publications

References 18 publications

Classical density functional study of wetting transitions on nanopatterned surfaces

Classical density functional study of wetting transitions on nanopatterned surfaces

Transition temperatures and contact angles in the sequential-wetting scenario of n-alkanes on (salt) water

Effect of ion hydration on the first-order transition in the sequential wetting of hexane on brine

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