Thermodynamic analysis on wetting state transitions of rough surfaces with 3D irregular microstructure

Sui, Xin; Tam, Jason; Erb, U.; Liang, Wenyan

doi:10.1016/j.surfin.2022.102378

Cited by 3 publications

(12 citation statements)

References 55 publications

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“…The median icing delay time for this distribution can be described as follows t R J ( , ) 5 ln 2 3 ( , ) med a 0 a 3/5 i k j j j j j j y { z z z z z z = (28) where k, and A int denote a kinetic constant, Boltzmann's constant, the time to ice formation, the advancing water contact angle, and the geometric substrate-liquid "apparent" contact area, T is 271 K (−2 °C). 31,32 These equations show that the delay time of ice formation on a hydrophobic surface depends mainly on the solid−liquid contact area A int and the contact angle θ.…”

Section: Resultsmentioning

confidence: 99%

“…During droplet retreat, Young’s equation is locally valid as follows where γ la , γ sa , and γ ls are the interfacial tension between the liquid–gas, solid-gas, and solid–liquid interfaces, respectively. The change in surface energy when the droplet recedes at different positions can be described as follows The adhesion energy consumed by detaching from the microstructure unit length during droplet retreat is given as follows When the droplets reached maximum spreading, the number of nanorods touching at the three structural scales are denoted as n 1 , n 2 , and n 3 , respectively. − The adhesion energy consumed during the droplet rebound process is respectively given below The initial kinetic energy of the droplet at the moment of falling on the surface of different scales is the same as the surface energy. The surface energy of the droplet after rebounding to the highest height is the same as the initial surface energy, and the initial kinetic energy is converted into potential energy, adhesion loss energy, and potential energy for microstructural deformation after rebound.…”

Section: Resultsmentioning

confidence: 99%

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Dynamic Anti-Icing Performance of Flexible Hybrid Superhydropohobic Surfaces

Hou,

Zhan,

Fan

et al. 2023

ACS Appl. Mater. Interfaces

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Normal superhydrophobic surfaces with a rough topography provide pocketed air at the solid−liquid interface, which guides the droplet to easily detach from the surface at room temperature. However, at low temperatures, this function attenuates obviously. In this research, a flexible hybrid topography with submillimeter (sub-mm) and microcone arrays is designed to adjust the impacting behavior of the droplet. The sub-mm cone could provide rigid support to limit deformation, leading to reduced energy consumption during impact processes. However, the microcone could maintain surface superhydrophobicity under different conditions, preventing droplet breakage and the change of the droplet contact state during impact processes by providing multiple contact points. Under the synergistic effect, such a hybrid structure could provide much more pocket air at the solid−liquid interface to limit the spreading of liquid droplets and reduce the energy loss during the impact process. At a low temperature (−5 °C), even if the impact height is reduced to 1 cm, the droplets still could be bound off, and the hybrid superhydrophobic surface presents excellent dynamic anti-icing ability. The special flexible hybrid superhydropohobic surface has potential application in fast self-cleaning and anti-icing fields.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Dynamic Anti-Icing Performance of Flexible Hybrid Superhydropohobic Surfaces

Hou,

Zhan,

Fan

et al. 2023

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

show abstract

“…The most commonly used method for thermodynamic simulation of the wetting transition is finite element analysis. [ 44a,51 ] The entire composite system is broken down into a multitude of small, simple units that interact with one another, and the small units are analyzed energetically. The motion environment is simplified, and the energy of all the small units is integrated to deduce the energy variation of the whole system.…”

Section: Fundamental Understanding Of Superhydrophobicitymentioning

confidence: 99%

“…A large number of thermodynamic studies have been conducted to analyze the C‐W transformation mechanism. This ranges from analyzing simple 2D models [ 43 ] to more complex three‐dimensional models, [ 44 ] along with simulations and assessments of single, uniformly distributed arrays and complex, diverse microstructurally arranged surfaces. Moreover, it extends from general thermodynamic analyses to the exploration of specific model simulations.…”

Section: Fundamental Understanding Of Superhydrophobicitymentioning

confidence: 99%

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The Challenge of Superhydrophobicity: Environmentally Facilitated Cassie–Wenzel Transitions and Structural Design

Zhong,

Xie,

Guo

2023

Advanced Science

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Superhydrophobic materials can be used in various fields to optimize production and life due to their unique surface wetting properties. However, under certain pressure and perturbation conditions, the droplets deposited on superhydrophobic materials are prone to change from Cassie state to Wenzel state, which limits the practical applications of the materials. In recent years, a large number of works have investigated the transition behavior, transition mechanism, and influencing factors of the wetting transition that occurs when a superhydrophobic surface is under a series of external environments. Based on these works, in this paper, the phenomenon and kinetic behavior of the destruction of the Cassie state and the mechanism of the wetting transition are systematically summarized under external conditions that promote the wetting transition on the material surface, including pressure, impact, evaporation, vibration, and electric wetting. In addition, superhydrophobic surface morphology has been shown to directly affect the duration of the Cassie state. Based on the published work the effects of specific morphology on the Cassie state, including structural size, structural shape, and structural level, are summarized in this paper from theoretical analyses and experimental data.

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Factors influencing wettability and surface/interface mechanics of plant surfaces: a review

Tie,

Gao,

Huang

et al. 2023

Front. Mater.

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A wide variety of abundant plant leaves exist in nature, and the wettability of their surfaces is formed to adapt to diverse external environments. In this paper we will focus on the factors influencing the wettability of various plant leaves prevalent in nature. And we hope to investigate the interfacial problems of plants from a mechanical point of view. It is found that there are many factors affecting the surface wettability of leaves, such as chemical composition, surface microstructures, hierarchical structures, and growth age. Different influencing factors have different contributions to the change of surface wettability. The surface wax composition influences the surface wettability from a chemical point of view while the hierarchical structure consisting of nanostructures and micron structures also influences the wettability from a structural point of view. Also as the growth age of the plant increases, there is a combined effect on the chemical composition and microstructure of the leaves. Then we discuss the surface/interface mechanics of droplets on various plant leaves and analyze the wetting properties of droplets on different substrates. Finally, we hope that the surface/interface mechanics of plant leaves may be systematically utilized in the future for the preparation of multifunctional biomimetic materials, realizing the crossover of chemistry, biology, mechanics, and other materials science fields.

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Thermodynamic analysis on wetting state transitions of rough surfaces with 3D irregular microstructure

Cited by 3 publications

References 55 publications

Dynamic Anti-Icing Performance of Flexible Hybrid Superhydropohobic Surfaces

Dynamic Anti-Icing Performance of Flexible Hybrid Superhydropohobic Surfaces

The Challenge of Superhydrophobicity: Environmentally Facilitated Cassie–Wenzel Transitions and Structural Design

Factors influencing wettability and surface/interface mechanics of plant surfaces: a review

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