Generalized line tension of water nanodroplets

Kanduč, Matej; Eixeres, Laila; Liese, Susanne; Netz, Roland R.

doi:10.1103/physreve.98.032804

Cited by 38 publications

(29 citation statements)

References 67 publications

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“…Such line tension effects can be mitigated by using a cylindrical droplet that is infinitely long (due to periodic boundaries), because the three-phase contact line then has a fixed length and is independent of droplet size 23 . However, a number of studies have recently shown that θ extracted from the geometry of such cylindrical droplets nevertheless depends on the curvature of the droplet [24][25][26] . In addition to the challenges posed by line tension and finite size effects, the determination of θ from droplet geometry is also plagued by a certain degree of ambiguity regarding the exact location of the solid-fluid interface [27][28][29] .…”

Section: A Introductionmentioning

confidence: 99%

Characterizing surface wetting and interfacial properties using enhanced sampling (SWIPES)

et al. 2019

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We introduce an accurate and efficient method for characterizing surface wetting and interfacial properties, such as the contact angle made by a liquid droplet on a solid surface, and the vapor-liquid surface tension of a fluid. The method makes use of molecular simulations in conjunction with the indirect umbrella sampling technique to systematically wet the surface and estimate the corresponding free energy. To illustrate the method, we study the wetting of a family of Lennard-Jones surfaces by water. We estimate contact angles for surfaces with a wide range of attractions for water by using our method and also by using droplet shapes. Notably, as surface -water attractions are increased, our method is able to capture the transition from partial to complete wetting. Finally, the method is straightforward to implement and computationally efficient, providing accurate contact angle estimates in roughly 5 nanoseconds of simulation time. A. IntroductionWetting of solid surfaces by fluids is important in diverse disciplines, including but not limited to surface chemistry, materials characterization, oil and gas recovery 1-5 . In general, the wettability of a solid by a fluid is characterized by a wetting coefficient, k ≡ (γ SV − γ SL )/γ VL , where γ represents surface tension, and the subscripts correspond to the coexisting vapor (V), liquid (L) and solid (S) phases. The wetting coefficient is also related to the contact angle (θ ) that a liquid droplet (surrounded by its vapor) makes with a solid surface; according to Young's equation, cos θ = (γ SV − γ SL )/γ VL = k. Thus, the extent to which a fluid prefers to wet a solid, or the preference of the solid for the

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Section: A Introductionmentioning

confidence: 99%

Characterizing surface wetting and interfacial properties using enhanced sampling (SWIPES)

et al. 2019

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“…LG (1) where γ LG , γ SG , and γ LS are the liquid-gas, solid-gas, and liquid-solid interfacial tensions and θ ∞ and θ are the contact angles of a macroscopic droplet and a droplet with the contact radius r, respectively. Here, τ represents not only the thermodynamic line tension, but also the curvature-dependent surface tension and line contribution effects [9][10][11][12], and thus, it is referred to as the apparent line tension.…”

Section: Introductionmentioning

confidence: 99%

Line Tension and Drop Size Dependence of Contact Angle at the Nanoscale

2022

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Despite considerable research efforts, the influence of contact line tension during wetting at the nanoscale and its experimental determination remain challenging tasks. So far, molecular dynamics simulations and atomic force microscope measurements have contributed to the understanding of these phenomena. However, a direct measurement of the size dependence of the contact angle and the magnitude of the apparent line tension has not been realized so far. Here, we show that the contact angle is indeed dependent on the drop size for small drop diameters and determine the magnitude of the apparent line tension via liquid-metal based measurements of advancing and receding contact angle inside a scanning electron microscope. For this purpose, a robotic setup inside an electron microscope chamber and oxide-free Galinstan droplets—produced via an electromigration-based and focused ion beam irradiation-assisted process—are employed. Using the first-order correction of Young’s equation, we find an apparent line tension value of 4.02 × 10−7 J/m for Galinstan© on stainless steel.

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“…Therefore, the curvature correction which is represented by the Tolman's length can be negative for convex surface and positive for concave surface [56]. In fact, several model calculations [56,57] indicate both positive and negative Tolman's length. The issue of curvature-dependent surface tension for membranes and vesicles with elastic surface is also well know.…”

Section: Concave Cap-cap Geometrymentioning

confidence: 99%

“…Therefore, the effect of size-or curvature-dependent liquid-vapor surface tension to the capillary bridge might not be negligible. Of course, the line tension is not merely a phenomenological parameter but it needs detailed consideration and should be interpreted as an effective line tension which includes various nanoscale effects such as the disjoining pressure [40,41], Tolman's correction to the surface tension [49,57,60] and the adsorption to the substrate [61,62]. At the present stage, even the sign of line tension is unpredictable.…”

Section: Concave Cap-cap Geometrymentioning

confidence: 99%

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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Generalized line tension of water nanodroplets

Cited by 38 publications

References 67 publications

Characterizing surface wetting and interfacial properties using enhanced sampling (SWIPES)

Characterizing surface wetting and interfacial properties using enhanced sampling (SWIPES)

Line Tension and Drop Size Dependence of Contact Angle at the Nanoscale

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

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