Contact angles of a drop pinned on an incline

Coninck, J. De; Dunlop, François; Huillet, Thierry

doi:10.1103/physreve.95.052805

Cited by 23 publications

(52 citation statements)

References 30 publications

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“…The most effective hydrophobic surfaces found in nature are created using a microstructure, such as that in butterfly wings or the surfaces of lotus plants, and it has been shown that varying the microstructure of such a coating can modify the hydrophobicity of a surface, as well as the wetting properties [4][5][6]. The two extreme conditions for microstructure wetting are the Wenzel state, where the microstructure is filled with fluid, and the Cassie-Baxter state, where fluid is pinned on the entrance and exit corners of the microstructure [7][8][9]. Previous studies have shown that a microstructure comprised of spherical polytetrafluoroethylene (PTFE) nanoparticles is able to produce a superhydrophobic surface, with contact angles greater than 140 • [10,11] such as the surface shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Effect of PTFE Particle Size on Superhydrophobic Coating for Supercooled Water Prevention

2018

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Polytetrafluoroethylene (PTFE) chemically repels water droplets due to the nature of fluorine substituents. This paper presents an experimental study on the impact of PTFE particle size and temperature on the hydrophobicity of a surface. The present study analyzes hydrophobicity due to both the chemical properties of PTFE and the microstructure created by PTFE particles. Herein, studies of the contact angle and the sliding angle of these surfaces are described in supercooled-water conditions ranging from −10 to 0 °C. From the equations governing the surface tension and sliding angle of a droplet on a superhydrophobic surface, it is found that particle size has a much greater effect on hydrophobicity than temperature. An increase in the PTFE particle size greatly reduces the sliding angle, which indicates a lower amount of energy required to remove the droplet from the surface.

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Section: Introductionmentioning

confidence: 99%

Effect of PTFE Particle Size on Superhydrophobic Coating for Supercooled Water Prevention

2018

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“…3, [28] Eq. 4 and [9] Eqs. 1 and 2), concluding to k varying in the range π/2 ≤ k ≤ 2, depending on the physical situation.…”

Section: Introductionmentioning

confidence: 99%

Pinning of a drop by a junction on an incline

et al. 2017

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The shape of a drop pinned on an inclined substrate is a long-standing problem where the complexity of real surfaces, with heterogeneities and hysteresis, makes it complicated to understand the mechanisms behind the phenomena. Here we consider the simple case of a drop pinned on an incline at the junction between a hydrophilic half-plane (the top half) and a hydrophobic one (the bottom half). Relying on the equilibrium equations deriving from the balance of forces, we exhibit three scenarii depending on the way the contact line of the drop on the substrate either simply leans against the junction or overfills (partly or fully) into the hydrophobic side. We draw some conclusions on the geometry of the overlap and the stability of these tentative equilibrium states. In the corresponding retention force factor, we find that a major role is played by the wetted length of the junction line, in the spirit of Furmidge's observations. The predictions of the theory are compared with extensive molecular dynamics simulations.

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“…[1,3,5]), is that the shape of the footprint does not remain circular for α > 0. However, since most of the analytical approaches restrict to small values of α, those studies have considered a circular shape for the footprint [15,25]. Instead, we will extend now our previous theory in [27] for non-circular footprints on horizontal planes to inclined ones.…”

Section: Drop Shapementioning

confidence: 96%

“…The prediction for = 1 is compared with the small Bo theory developed by De Coninck et al [15], which is developed without the lubrication approximation. This solution for θ(ϕ) is written in the form…”

Section: A Contact Angle Distribution Along the Drop Peripherymentioning

confidence: 99%

Contact-angle-hysteresis effects on a drop sitting on an incline plane

et al. 2019

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We study the contact angle hysteresis and morphology changes of a liquid drop sitting on a solid substrate inclined with respect to the horizontal at an angle α. This one is always smaller than the critical one, αcrit, above which the drop would start to slide down. The hysteresis cycle is performed for positive and negative α's (|α| < αcrit), and a complete study of the changes in contact angles, free surface and footprint shape is carried out. The drop shape is analyzed in terms of a solution of the equilibrium pressure equation within and out of the long-wave model (lubrication approximation). Within this approximation, we obtain a truncated analytical solution that describes the static drop shapes, that is successfully compared with experimental data. This solution is of practical interest since it allows for a complete description of all the drop features, such as its footprint shape or contact angle distribution around the drop periphery, starting from a very small set of relatively easy to measure drop parameters. arXiv:1809.11157v1 [physics.flu-dyn]

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Contact angles of a drop pinned on an incline

Cited by 23 publications

References 30 publications

Effect of PTFE Particle Size on Superhydrophobic Coating for Supercooled Water Prevention

Effect of PTFE Particle Size on Superhydrophobic Coating for Supercooled Water Prevention

Pinning of a drop by a junction on an incline

Contact-angle-hysteresis effects on a drop sitting on an incline plane

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