Bridging of liquid drops at chemically structured walls

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

doi:10.1103/physreve.99.042804

Cited by 9 publications

(12 citation statements)

References 39 publications

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“…When the wall is geometrically sculpted or chemically patterned the fluid adsorption can exhibit a zoo of new possibilities [8][9][10][11][12][13][14][15][16][17]. Attempts to understand this date back to the empirical work of Wenzel [18] (for sculpted or rough surfaces) and Cassie [19] for chemically patterned (planar) walls.…”

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confidence: 99%

Scaling of wetting and prewetting transitions on nanopatterned walls

et al. 2019

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We consider a nano-patterned planar wall consisting of a periodic array of stripes of width L, which are completely wet by liquid (contact angle θ = 0), separated by regions of width D which are completely dry (contact angle θ = π). Using microscopic Density Functional Theory we show that in the presence of long-ranged dispersion forces, the wall-gas interface undergoes a first-order wetting transition, at bulk coexistence, as the separation D is reduced to a value Dw ∝ ln L, induced by the bridging between neighboring liquid droplets. Associated with this is a line of pre-wetting transitions occurring off coexistence. By varying the stripe width L we show that the pre-wetting line shows universal scaling behaviour and data collapse. This verifies predictions based on mesoscopic models for the scaling properties associated with finite-size effects at complete wetting including the logarithmic singular contribution to the surface free-energy.

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confidence: 99%

Scaling of wetting and prewetting transitions on nanopatterned walls

et al. 2019

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“…They reached this conclusion by comparing the results from the classical capillary theory with those from the non-local density functional theory [29,31], which is more accurate than the local square-gradient density functional theory [38] or the second gradient theory [39]. There are growing evidences that the classical capillary theory is accurate down to the order of nanometer and that it can be served as a minimal model of nanoscale liquids [29,31]. The effect of disjoining pressure or the surface potential, for example, can be partly taken into account by the line tension [40,41].…”

Section: Introductionmentioning

confidence: 95%

“…Since the nanoscale liquid bridges can easily form even in the low relative humidity, it is * Permanent address Tokyo City University, Setagaya-ku, Tokyo 158-8557, Japan; iwamatm@tcu.ac.jp (corresponding author) also a convenient tool to study the surface properties such as the size-dependence of surface tension of the nanoscale liquid bridges [16,24]. It can also serve as a testing ground of various statistical mechanical theory of nanoscale liquids [27][28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

“…In fact, Malijevský and Parry [37] recently showed that the prediction of capillary condensation from the classical capillary theory remains highly accurate down to the order of tens of molecular diameters. They reached this conclusion by comparing the results from the classical capillary theory with those from the non-local density functional theory [29,31], which is more accurate than the local square-gradient density functional theory [38] or the second gradient theory [39]. There are growing evidences that the classical capillary theory is accurate down to the order of nanometer and that it can be served as a minimal model of nanoscale liquids [29,31].…”

Section: Introductionmentioning

confidence: 99%

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Effect of line tension on axisymmetric nanoscale capillary bridges at the liquid-vapor equilibrium

Iwamatsu

Mori

2019

Phys. Rev. E

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The effect of line tension on the axisymmetric nanoscale capillary bridge between two identical substrates with convex, concave and flat geometry at the liquid-vapor equilibrium is theoretically studied. The modified Young's equation for the contact angle, which takes into account the effect of line tension is derived on a general axisymmetric curved surface using the variational method. Even without the effect of line tension, the parameter space where the bridge can exist is limited simply by the geometry of substrates. The modified Young's equation further restricts the space where the bridge can exist when the line tension is positive because the equilibrium contact angle always remain finite and the wetting state near the zero contact angle cannot be realized. It is shown that the interplay of the geometry and the positive line tension restricts the formation of capillary bridge.

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“…This, in turn, invoked theoretical and computational efforts for a description of liquid adsorption on chemically heterogenous surfaces by considering further aspects, additional to the surface tension arguments, such as the relevance of microscopic forces, packing effects, thermal fluctuations, line tension etc., all ignored within the original description of Cassie. These include molecular based simulations [15][16][17][18][19][20][21][22], stability analysis of liquid structures at microchannels [6,[23][24][25][26][27], exact statistical-mechanical arguments [28,29], various modifications of the effective Hamiltonian model [30][31][32][33], as well as studies using den- sity functional theory (DFT) approach [34][35][36][37][38][39][40][41][42][43].…”

Section: Introductionmentioning

confidence: 99%

Symmetry-breaking morphological transitions at chemically nanopatterned walls

Pospíšil¹,

Láska²,

Malijevský³

2019

Phys. Rev. E

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We study the structure and morphological changes of fluids that are in contact with solid composites formed by alternating and microscopically wide stripes of two different materials. One type of the stripes interacts with the fluid via long-ranged Lennard-Jones-like potential and tends to be completely wet, while the other type is purely repulsive and thus tends to be completely dry. We consider closed systems with a fixed number of particles that allows for stabilization of fluid configurations breaking the lateral symmetry of the wall potential. These include liquid morphologies corresponding to a sessile drop that is formed by a sequence of bridging transitions that connect neighboring wet regions adsorbed at the attractive stripes. We study the character of the transitions depending on the wall composition, stripes width, and system size. Using a (classical) nonlocal density functional theory (DFT), we show that the transitions between different liquid morphologies are typically weakly first-order but become rounded if the wavelength of the system is lower than a certain critical value Lc. We also argue that in the thermodynamic limit, i.e., for macroscopically large systems, the wall becomes wet via an infinite sequence of first-order bridging transitions that are, however, getting rapidly weaker and weaker and eventually become indistinguishable from a continuous process as the size of the bridging drop increases. Finally, we construct the global phase diagram and study the density dependence of the contact angle of the bridging drops using DFT density profiles and a simple macroscopic theory. arXiv:1912.12111v1 [cond-mat.stat-mech]

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Bridging of liquid drops at chemically structured walls

Cited by 9 publications

References 39 publications

Scaling of wetting and prewetting transitions on nanopatterned walls

Scaling of wetting and prewetting transitions on nanopatterned walls

Effect of line tension on axisymmetric nanoscale capillary bridges at the liquid-vapor equilibrium

Symmetry-breaking morphological transitions at chemically nanopatterned walls

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