Hysteresis of the Contact Angle of a Meniscus Inside a Capillary with Smooth, Homogeneous Solid Walls

Kuchin, I. V.; Starov, Victor

doi:10.1021/acs.langmuir.6b00721

Cited by 22 publications

(22 citation statements)

References 23 publications

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“…40,69 Another manifestation of the first-order wetting transition is the contact angle hysteresis, mainly dominated by surface roughness and chemical heterogeneity, but on flat homogeneous surfaces also a direct consequence of the first-order nature of wetting transitions. 37,[70][71][72] Figure 9 shows the reduction of the wetting coefficient versus the film thickness at different RHs for three surface polarities. Higher RHs lead to thicker water films as well as smaller wetting coefficient k w of the surface.…”

Section: Wetting Off Coexistencementioning

confidence: 99%

Atomistic simulations of wetting properties and water films on hydrophilic surfaces

Kanduč

Netz

2017

The Journal of Chemical Physics

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We use molecular simulations to investigate the wetting behavior of water at flat polar surfaces. Introducing a computational procedure based on thermodynamic integration methods, we determine the equilibrium water film thickness on the surface at given vapor density as well as the corresponding change of the surface free energy. The wetting film is relevant on polar surfaces near the wetting transition and significantly alters the surface contact angle. For thin films, the surface free energy change increases linearly with the thickness, as predicted by simple thermodynamic arguments. For thick films we observe deviations from linearity, which we rationalize by the formation of hydrogen bonds between water molecules in the film. Our approach provides an efficient and accurate technique to calculate the wetting properties of surface layers, which we verify by simulating water droplets on the surfaces.

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Section: Wetting Off Coexistencementioning

confidence: 99%

Atomistic simulations of wetting properties and water films on hydrophilic surfaces

Kanduč

Netz

2017

The Journal of Chemical Physics

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“…Hence the meniscus gets stuck or pinned at the hardly smooth natural surface of the solid. This pinning phenomenon or formally contact line pinning (CLP) causes the contact angle hysteresis (a difference between the maximum and minimum h) [44]. Contact angle hysteresis, therefore, suggests that there is no unique value for contact angle even at static equilibrium [45].…”

Section: Mathematical Modelingmentioning

confidence: 99%

Conceptual modeling of temperature effects on capillary pressure in dead-end pores

Biswas

Kartha

2019

Sādhanā

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The effect of temperature on the liquid-gas interface and consequently on the capillary pressure in unsaturated dead-end pores is conceptually modeled in this paper. Trapping of non-wetting fluid (e.g., air) in the dead-end pores impacts the capillary pressure-saturation relationship and affects the continuous flow of wetting fluids. In the dead-end pore, which is assumed to be a simple vertical cylindrical capillary tube with one end closed and the other end open to the liquid body, the dependence of solid-liquid and solid-air interfacial tensions on temperature and its subsequent effects on the contact angles are deduced. A non-linear ordinary differential equation, using the Young-Laplace equation, in terms of a contact-angle-sensitive temperature function is derived and numerically solved using the fourth order Runge-Kutta method. This temperature function is used to obtain the capillary pressure-temperature relationship for a solid-liquid-air capillary system. Two example problems, first a glass-water-air capillary system and second a polytetrafluoroethylene-n-hexadecane-air capillary system, are solved here. A linear decrease in capillary pressure with temperature is observed, suggesting that entrapped air affects capillary pressure in dead-end pores. A similar linear decrease in capillary pressure, consistent with experimental observations, is observed for open-end pores.

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“…However, these are not the only causes for the existence of contact angles hysteresis. Lately researchers have illustrated that hysteresis exist on smooth homogeneous solid substrates [38][39][40]. It has been observed that contact angle hysteresis on a rigid substrate is dependent on surface forces action in the vicinity of the three-phase contact line [16].…”

Section: Theoretical and Experimental Analysismentioning

confidence: 99%

Sessile Droplets on Deformable Substrates

Ahmed

Koursari

Trybała

et al. 2018

Colloids and Interfaces

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Wetting of deformable substrates has gained significant interest over the past decade due to a multiplicity of industrial and biological applications. Technological advances in the area of interfacial science have given rise to the ability to capture interfacial behavior between a liquid droplet and an elastic substrate. Researchers have developed several theories to explain the interaction between the two phases and describe the process of wetting of deformable/soft substrates. A summary of the most recent advances on static wetting of deformable substrates is given in this review. It is demonstrated that action of surface forces (disjoining/conjoining pressure) near the apparent three-phase contact line should be considered. Any consideration of equilibrium droplets on deformable (as well as on non-deformable) substrates should be based on consideration of the excess free energy of the system. The equilibrium shapes of both droplet and deformable substrate should correspond to the minimum of the excess free energy of the system. It has never been considered in the literature that the obtained equilibrium profiles must satisfy sufficient Jacobi’s condition. If Jacobi’s condition is not satisfied, it is impossible to claim that the obtained solution really corresponds to equilibrium. In recently published studies, equilibrium of droplets on deformable substrates: (1) provided a solution that corresponds to the minimum of the excess free energy; and (2) the obtained solution satisfies the Jacobi’s condition. Based on consideration of disjoining/conjoining pressure acting in the vicinity of the apparent three-phase contact line, the hysteresis of contact angle of sessile droplets on deformable substrates is considered. It is shown that both advancing and receding contact angles decrease as the elasticity of the substrate is increased and the effect of disjoining/conjoining pressure is discussed. Fluid inside the droplet partially wets the deformable substrate. It is shown that just these forces coupled with the surface elasticity determine the deformation of the deformable substrates.

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Hysteresis of the Contact Angle of a Meniscus Inside a Capillary with Smooth, Homogeneous Solid Walls

Cited by 22 publications

References 23 publications

Atomistic simulations of wetting properties and water films on hydrophilic surfaces

Atomistic simulations of wetting properties and water films on hydrophilic surfaces

Conceptual modeling of temperature effects on capillary pressure in dead-end pores

Sessile Droplets on Deformable Substrates

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