Scaling of wetting and prewetting transitions on nanopatterned walls

Pospíšil, Martin; Láska, Martin; Parry, A. O.; Malijevský, Alexandr

doi:10.1103/physreve.100.032801

Cited by 7 publications

(8 citation statements)

References 25 publications

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“…Also, the capillary critical point at this temperature is about L c ≈ 6 σ, while the depinning line terminates only at L g ≈ σ in which case the fluid atoms cannot intrude the grooves anymore due to excluded volume effects. Note that for even smaller values of L g the depinning transition would be replaced by the bridging transition on a planar but chemically heterogenous wall consisting of periodically repeating hydrophilic and hydrophobic stripes [59].…”

Section: B Depinningmentioning

confidence: 99%

Filling, depinning, unbinding: Three adsorption regimes for nanocorrugated substrates

Malijevský

2020

Phys. Rev. E

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We study adsorption at periodically corrugated substrates formed by scoring rectangular grooves into a planar solid wall which interacts with the fluid via long-range (dispersion) forces. The grooves are assumed to be macroscopically long but their depth, width and separations can all be molecularly small. We show that the entire adsorption process can be divided into three parts consisting of (i) filling the grooves by a capillary liquid; (ii) depinning of the liquid-gas interface from the wall edges; and (iii) unbinding of the interface from the top of the wall, which is accompanied by a rapid but continuous flattening of its shape. Using a nonlocal density functional theory and mesoscopic interfacial models all the regimes are discussed in some detail to reveal the complexity of the entire process and subtle aspects that affect its behaviour. In particular, it is shown that the nature of the depinning phenomenon is governed by the width of the wall pillars (separating grooves), whilst the grooves width only controls the location of the depinning first-order transition, if present.

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Section: B Depinningmentioning

confidence: 99%

Filling, depinning, unbinding: Three adsorption regimes for nanocorrugated substrates

Malijevský

2020

Phys. Rev. E

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“…Thus the boundaries between the domains still depend parametrically on ratios between the number densities; we only made use of the inequalities in Eq. (22). Moreover, the equation defining the separatrix Y K(X,Y ) implicitly depends even on Y via the equilibrium thicknesses l wβγ and l wαγ of the wetting films.…”

Section: Iii2 Fluid-fluid and Fluid-wall Interactions Exhibiting The ...mentioning

confidence: 99%

“…Numerous studies have been devoted to the classification of the wetting behavior at individual, planar fluid-fluid and fluid-solid interfaces, including binary liquid mixtures [4][5][6][7][8][9][10][11]. Wetting in more complicated surface geometries [12][13][14][15][16][17][18] and at chemically inhomogeneous surfaces [19][20][21][22] have been extensively studied as well.…”

Section: Introductionmentioning

confidence: 99%

Wetting behavior of a colloidal particle trapped at a composite liquid-vapor interface of a binary liquid mixture

Kim,

Schimmele,

Dietrich

2020

Preprint

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A partially miscible binary liquid mixture, composed of A and B particles, is considered theoretically under conditions for which a stable A-rich liquid phase is in thermal equilibrium with the vapor phase. The B-rich liquid is metastable. The liquids and the thermodynamic conditions are chosen such, that the interface between the A-rich liquid and the vapor contains an intervening wetting film of the B-rich phase. In order to obtain information about the large-scale fluid structure around a colloidal particle, which is trapped at such a composite liquid-vapor interface, three related and linked wetting phenomena at planar liquid-vapor, wall-liquid, and wall-vapor interfaces are studied analytically, using classical density functional theory in conjunction with the sharp-kink approximation for the number density profiles of the A and B particles. If in accordance with the so-called mixing rule the strength of the A-B interaction is given by the geometric mean of the strengths of the A-A and B-B interactions, and similarly the ratio between the wall-A and the wall-B interaction, the scenario, in which the colloid is enclosed by a film of the B-rich liquid, can be excluded. Up to six distinct wetting scenarios are possible, if the above mixing rules for the fluid-wall and for the fluid-fluid interactions are relaxed. The way the space of system parameters is divided into domains corresponding to the six scenarios, and which of the domains actually appear, depends on the signs of the deviations from the mixing rule prescriptions. Relevant domains, corresponding, e.g., to the scenario in which the colloid is enclosed by a film of the B-rich liquid, emerge, if the ratio between the strengths of the wall-A and the wall-B interactions is reduced as compared to the mixing rule prescription, or if the strength of the A-B interaction is increased to values above the one from the mixing rule prescription. The range, within which the contact angle may vary inside the various domains, is also studied.

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“…If the adsorbing wall is heterogenous, such that its surface is modified chemically or geometrically, the wetting phenomena become considerably more intricate in comparison with a homogenous and perfectly flat wall considered above. The process of complete wetting may then be accompanied by a plenty of other interfacial phenomena such as filling [9][10][11][12][13][14][15][16][17][18][19][20][21][22], unbending [23][24][25], depinning [26][27][28], bridging [29][30][31] and other morphological transitions [32][33][34][35][36][37][38][39][40][41][42], whose interplay may give rise to very complex phase behaviour of the adsorbed fluid. In this work, let us consider a substrate (wall) which is flat but decorated by a macroscopically long stripe of width L which is of a material with a greater affinity to the liquid phase than the rest of the wall, such that its wetting temperature T stripe w is lower than the wetting temperature of the wall T wall w .…”

Section: Introductionmentioning

confidence: 99%

Height of a liquid drop on a wetting stripe

Malijevský

2020

Phys. Rev. E

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Adsorption of liquid on a planar wall decorated by a hydrophilic stripe of width L is considered. Under the condition, that the wall is only partially wet (or dry) while the stripe tends to be wet completely, a liquid drop is formed above the stripe. The maximum height m(δµ) of the drop depends on the stripe width L and the chemical potential departure from saturation δµ where it adopts the value 0 = m(0). Assuming a long-range potential of van der Waals type exerted by the stripe, the interfacial Hamiltonian model is used to show that 0 is approached linearly with δµ with a slope which scales as L 2 over the region satisfying L ξ , where ξ is the parallel correlation function pertinent to the stripe. This suggests that near the saturation there exists a universal curve m(δµ) to which the adsorption isotherms corresponding to different values of L all collapse when appropriately rescaled. Although the series expansion based on the interfacial Hamiltonian model can be formed by considering higher order terms, a more appropriate approximation in the form of a rational function based on scaling arguments is proposed. The approximation is based on exact asymptotic results, namely that m ∼ δµ −1/3 for L → ∞ and that m obeys the correct δµ → 0 behaviour in line with the results of the interfacial Hamiltonian model. All the predictions are verified by the comparison with a microscopic density functional theory (DFT) and, in particular, the rational function approximation-even in its simplest form-is shown to be in a very reasonable agreement with DFT for a broad range of both δµ and L.

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Scaling of wetting and prewetting transitions on nanopatterned walls

Cited by 7 publications

References 25 publications

Filling, depinning, unbinding: Three adsorption regimes for nanocorrugated substrates

Filling, depinning, unbinding: Three adsorption regimes for nanocorrugated substrates

Wetting behavior of a colloidal particle trapped at a composite liquid-vapor interface of a binary liquid mixture

Height of a liquid drop on a wetting stripe

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