Geometric and chemical nonuniformity may induce the stability of more than one wetting state in the same hydrophobic surface

Lazzari, Davi; Brito, Carolina

doi:10.1103/physreve.99.032801

Cited by 6 publications

(3 citation statements)

References 49 publications

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“…As a consequence, microscopic contact angle is inadequate to characterize the physics of wetting in a universal way. To date, several attempts have been made to address this problem, primarily relying on the machinery of nonextensive thermodynamics (Blunt et al, 2019;Lazzari & Brito, 2019;Yu et al, 2015). However, a local equilibrium state is often assumed and the energy dissipation in the system during dynamic fluid displacement events is ignored (Berg et al, 2013;Blunt et al, 2019).…”

Section: 1029/2019gl086151mentioning

confidence: 99%

Probing Effective Wetting in Subsurface Systems

Sun

McClure

Mostaghimi

et al. 2020

Geophysical Research Letters

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Wetting phenomena are of central importance for many natural and technological processes in subsurface geosciences. Surface roughness, chemical heterogeneity, and dynamic effects cause the microscopic contact angle to vary widely in subsurface multiphase systems. These effects must be characterized in a fundamental and transparent way to determine the overall state of wetting. Here, we apply the Gauss‐Bonnet theorem to establish a direct link between the contact angle and bulk fluid topology based on a newly defined term, deficit curvature. The resulting macroscopic measure is able to capture the average effects of complex microscopic variations in contact angle based on intrinsic geometric constraints that are imposed on the curvature of the contact line as a consequence of fluid topology. We show that deficit curvature is able to capture the effects of contact angle hysteresis and describe wetting in multiphase systems where geometrically complex contact lines are present along with surface heterogeneity.

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Section: 1029/2019gl086151mentioning

confidence: 99%

Probing Effective Wetting in Subsurface Systems

Sun

McClure

Mostaghimi

et al. 2020

Geophysical Research Letters

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“…The wetting state with minimum energy is the one that is favorable from the energetic viewpoint. Similar ideas where used by other authors 16,[26][27][28] including two of us [29][30][31] .…”

Section: Theoretical Continuous Modelmentioning

confidence: 77%

Modeling oil-water separation with controlled wetting properties

Gavazzoni,

Silvestrini,

Brito

2020

Preprint

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Several oil-water separation techniques have been proposed to improve the capacity of cleaning water. With the technological possibility of producing materials with antagonist wetting behavior, as for example a substrate that repeal water and absorb oil, the understanding of the properties that control this selective capacity has increased with the goal of being used as mechanism to separate mixed liquids. Besides the experimental advance in this field, less is known from the theoretical side. In this work we propose a theoretical model to predict the wetting properties of a given substrate and introduce simulations with a 4-spins cellular Potts model to study its efficiency in separating water from oil. Our results show that the efficiency of the substrates depends both on the interaction between the liquids and on the wetting behavior of the substrates itself. The water behavior of the droplet composed of both liquids is roughly controlled by the hidrophobicity of the substrate. To predict the oil behavior, however, is more complex because the substrate being oleophilic do not guarantee that the total amount of oil present on the droplet will be absorbed by the substrate. For both types of substrates considered is this work, pillared and porous with a reservoir, there is always an amount of reminiscent oil on the droplet which is not absorbed by the substrate due to the interaction with the water and the gas. Both theoretical and numerical models can be easily modified to analyse other types of substrates and liquids.

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“…Similar ideas were used by other authors, 16,[26][27][28] including two of us. [29][30][31] The geometry of the surfaces and the three-dimensional droplet considered in this work is shown in Fig. 1.…”

Section: Theoretical Continuous Modelmentioning

confidence: 99%

Modeling oil–water separation with controlled wetting properties

Gavazzoni

Silvestrini

Brito

2021

The Journal of Chemical Physics

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Several oil-water separation techniques have been proposed to improve the capacity of cleaning water. With the technological possibility of producing materials with antagonist wetting behavior, for example, a substrate that repels water and absorbs oil, the understanding of the properties that control this selective capacity has increased with the goal of being used as the mechanism to separate mixed liquids. Besides the experimental advance in this field, less is known from the theoretical side. In this work, we propose a theoretical model to predict the wetting properties of a given substrate and introduce simulations with a four-spin cellular Potts model to study its efficiency in separating water from oil. Our results show that the efficiency of the substrates depends both on the interaction between the liquids and on the wetting behavior of the substrates itself. The water behavior of the droplet composed of both liquids is roughly controlled by the hydrophobicity of the substrate. Predicting the oil behavior, however, is more complex because the substrate being oleophilic does not guarantee that the total amount of oil present on the droplet will be absorbed by the substrate. For both types of substrates considered in this work, pillared and porous with a reservoir, there is always an amount of reminiscent oil on the droplet, which is not absorbed by the substrate due to the interaction with the water and the gas. Both theoretical and numerical models can be easily modified to analyze other types of substrates and liquids.

show abstract

Geometric and chemical nonuniformity may induce the stability of more than one wetting state in the same hydrophobic surface

Cited by 6 publications

References 49 publications

Probing Effective Wetting in Subsurface Systems

Probing Effective Wetting in Subsurface Systems

Modeling oil-water separation with controlled wetting properties

Modeling oil–water separation with controlled wetting properties

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