Geometry Dependence of Wetting Tension on Charge-Modified Surfaces

Kang, Kwan Hyoung; Kang, In Seok; Lee, Choung Mook

doi:10.1021/la0342417

Cited by 17 publications

(39 citation statements)

References 24 publications

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“…holds, and the macroscopic contact angle θ cos θ = cos β − ψ [1 − 2φ(0, ϑ)] for χ 1 (15) was derived by Kang et al [31], requiring the potential φ(0, ϑ) at the TCL which they approximated by the zeroth-order potential φ (0) (0, ϑ). The first-order TCL potential…”

Section: B Macroscopic and Microscopic Contact Anglementioning

confidence: 99%

Line tension and reduction of apparent contact angle associated with electric double layers

Dörr¹,

Hardt²

2014

Physics of Fluids

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The line tension of an electrolyte wetting a non-polar substrate is computed analytically and numerically. The results show that, depending on the value of the apparent contact angle, positive or negative line tension values may be obtained. Furthermore, a significant difference between Young's contact angle and the apparent contact angle measured several Debye lengths remote from the three-phase contact line occurs. When applying the results to water wetting highly charged surfaces, line tension values of the same order of magnitude as found in recent experiments can be achieved. Therefore, the theory presented may contribute to the understanding of line tension measurements and points to the importance of the electrostatic line tension. Being strongly dependent on the interfacial charge density, electrostatic line tension is found to be tunable via the pH value of the involved electrolyte. As a practical consequence, the stability of nanoparticles adsorbed at fluid-fluid interfaces is predicted to be dependent on the pH value. The theory is suited for future incorporation of effects due to surfactants where even larger line tension values can be expected.

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Section: B Macroscopic and Microscopic Contact Anglementioning

confidence: 99%

Line tension and reduction of apparent contact angle associated with electric double layers

Dörr¹,

Hardt²

2014

Physics of Fluids

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“…The essential coefficients in the PB equation were considered as follows: the Debye length j À1 D ¼ 9:6 nm, the electric permittivity e ¼ 7:26 Â 10 À10 C 2 Jm for aqueous electrolytes, and b ¼ ze k B T ¼ 38:9 1 V for monovalent ionic species [39]. As mentioned in Section 1, the main purpose of this section is finding droplets in which potential distribution are onedimensional, by solving the PB equation numerically inside them.…”

Section: Boundary Conditionsmentioning

confidence: 99%

Lattice Boltzmann method for electrowetting modeling and simulation

Aminfar

Mohammadpourfard

2009

Computer Methods in Applied Mechanics and Engineering

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“…Condition (3) forces the potential to vanish at y → ∞, whereas (5) determines the normal electric field by prescribing the surface charge density. Condition (6) implies that the electric field vector is parallel to the oil-water interface for θ = α + π 2, whereas condition (4) expresses the fact the electric field becomes normal to the substrate surface for x → ∞, approaching asymptotically the far field solution φ(x → ∞, y) = exp(−y). In addition, the Green's function of Eq.…”

mentioning

confidence: 99%

“…In the next step, we propose expressions for the coefficients c and d (or b) from analytical considerations and compare them to numerical results. The relation for b is found from an asymptotic evaluation of the integral representation of the potential φ at the point (x, y) = (0, 0) to be of the form [5,6] φ ow (η 0 = 0) = φ(x = 0, y = 0) = b = e −d = π π + 2α (15) Furthermore, the gradient of φ at (x, y) = (0, 0) is parallel to the oil-water interface [cf. Fig.…”

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Electric-double-layer structure close to the three-phase contact line in an electrolyte wetting a solid substrate

Dörr

Hardt

2012

Phys. Rev. E

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The electric-double-layer structure in an electrolyte close to a solid substrate near the three-phase contact line is approximated by considering the linearized Poisson-Boltzmann equation in a wedge geometry. The mathematical approach complements the semianalytical solutions reported in the literature by providing easily available characteristic information on the double-layer structure. In particular, the model contains a length scale that quantifies the distance from the fluid-fluid interface over which this boundary influences the electric double layer. The analysis is based on an approximation for the equipotential lines. Excellent agreement between the model predictions and numerical results is achieved for a significant range of contact angles. The length scale quantifying the influence of the fluid-fluid interface is proportional to the Debye length and depends on the wall contact angle. It is shown that for contact angles approaching 90° there is a finite range of boundary influence.

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Geometry Dependence of Wetting Tension on Charge-Modified Surfaces

Cited by 17 publications

References 24 publications

Line tension and reduction of apparent contact angle associated with electric double layers

Line tension and reduction of apparent contact angle associated with electric double layers

Lattice Boltzmann method for electrowetting modeling and simulation

Electric-double-layer structure close to the three-phase contact line in an electrolyte wetting a solid substrate

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