Initial Electrospreading of Aqueous Electrolyte Drops

Chen, Longquan; Li, Chunli; Vegt, Nico F. A. van der; Auernhammer, Guenter K.; Bonaccurso, Elmar

doi:10.1103/physrevlett.110.026103

Cited by 29 publications

(22 citation statements)

References 36 publications

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“…This simple phenomenon is key for many industrial applications, and it has been a research topic for scientists and engineers for more than two centuries [1][2][3][4][5][6][7]. Benefitting also from the development of high speed video cameras, the entire spreading process became accessible in recent years, and experimental investigations especially about the early wetting regimes have been boosted by this technological progress [1,6,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Effects of surface wettability and liquid viscosity on the dynamic wetting of individual drops

2014

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In this paper, we experimentally investigated the dynamic spreading of liquid drops on solid surfaces. Drop of glycerol water mixtures and pure water that have comparable surface tensions (62.3-72.8 mN/m) but different viscosities (1.0-60.1 cP) were used. The size of the drops was 0.5-1.2 mm. Solid surfaces with different lyophilic and lyophobic coatings (equilibrium contact angle θ(eq) of 0°-112°) were used to study the effect of surface wettability. We show that surface wettability and liquid viscosity influence wetting dynamics and affect either the coefficient or the exponent of the power law that describes the growth of the wetting radius. In the early inertial wetting regime, the coefficient of the wetting power law increases with surface wettability but decreases with liquid viscosity. In contrast, the exponent of the power law does only depend on surface wettability as also reported in literature. It was further found that surface wettability does not affect the duration of inertial wetting, whereas the viscosity of the liquid does. For low viscosity liquids, the duration of inertial wetting corresponds to the time of capillary wave propagation, which can be determined by Lamb's drop oscillation model for inviscid liquids. For relatively high viscosity liquids, the inertial wetting time increases with liquid viscosity, which may due to the viscous damping of the surface capillary waves. Furthermore, we observed a viscous wetting regime only on surfaces with an equilibrium contact angle θ(eq) smaller than a critical angle θ(c) depending on viscosity. A scaling analysis based on Navier-Stokes equations is presented at the end, and the predicted θ(c) matches with experimental observations without any additional fitting parameters.

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Section: Introductionmentioning

confidence: 99%

Effects of surface wettability and liquid viscosity on the dynamic wetting of individual drops

2014

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“…Electrowetting on dielectric (EWOD) experiments on a flat surface have shown that application of voltage can speed up spreading ( 25 , 26 ). Decamps and De Coninck ( 27 ) developed a model for this experiment by including the electric contribution to surface energy in their MKT model for spreading.…”

Section: Introductionmentioning

confidence: 99%

Electrostatic cloaking of surface structure for dynamic wetting

et al. 2017

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“…5,12,14,15 The dynamics of electrowetting are rapid in this format, making it difficult to monitor the wetting dynamics. 16 Conductive surfaces, such as steel 17 and graphene/carbon nanotube films, 18 are being thus explored to lower the voltage and increase the timescale of electrowetting. However, the electrowetting is very slow and not readily reversible.…”

Section: Introductionmentioning

confidence: 99%

Low-Voltage Voltammetric Electrowetting of Graphite Surfaces by Ion Intercalation/Deintercalation

2016

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We demonstrate low-voltage electrowetting at the surface of freshly cleaved highly oriented pyrolytic graphite (HOPG). Using cyclic voltammetry (CV), electrowetting of a droplet of sodium perchlorate solution is observed at moderately positive potentials on high-quality (low step edge coverage) HOPG, leading to significant changes in contact angle and relative contact diameter that is comparable to the widely studied electrowetting on dielectric (EWOD) system, but over a much lower voltage range. The electrowetting behavior is found to be reasonably fast, reversible and repeatable for at least 20 cyclic scans (maximum tested). In contrast to classical electrowetting, e.g. EWOD, the electrowetting of the droplet on HOPG occurs with the intercalation/de-intercalation of anions between the graphene layers of graphite, driven by the applied potential, observed in the CV response, and detected by X-ray photoelectron spectroscopy. The electrowetting behavior is strongly influenced by those factors that affect the extent of the intercalation/de-intercalation of ions on graphite, such as scan rate, potential polarity, quality of the HOPG substrate (step edge and step height), and type of anion in the solution. In addition to perchlorate, sulfate salts also promote electrowetting, but some other salts do not. Our findings suggest a new mechanism for electrowetting based on ion intercalation and the results are of importance to fundamental 2 electrochemistry, as well as diversifying the means by which electrowetting can be controlled and applied.3

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Initial Electrospreading of Aqueous Electrolyte Drops

Cited by 29 publications

References 36 publications

Effects of surface wettability and liquid viscosity on the dynamic wetting of individual drops

Effects of surface wettability and liquid viscosity on the dynamic wetting of individual drops

Electrostatic cloaking of surface structure for dynamic wetting

Low-Voltage Voltammetric Electrowetting of Graphite Surfaces by Ion Intercalation/Deintercalation

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