Sliding of Water Droplets on Microstructured Hydrophobic Surfaces

Lv, Cunjing; Yang, Chi; Hao, Pengfei; He, Feng; Zheng, Quanshui

doi:10.1021/la9044495

Cited by 161 publications

(143 citation statements)

References 24 publications

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“…In other words, the larger the solid area fraction, the longer perimeter of contact line, and the stronger the adhesive forces between the water droplet and the solid surface. This is in agreement with available research findings [20,21].…”

Section: Measurement Of Dynamic Contact Angles and Internal Velocity supporting

confidence: 94%

Study of dynamic hydrophobicity of micro-structured hydrophobic surfaces and lotus leaves

Hao

Yao

Zhang

2011

Sci. China Phys. Mech. Astron.

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The dynamic wetting characteristics of water droplets on silicon wafers with microscale regular pillars structures and fresh lotus leaves are investigated experimentally. We measured the static contact angle, contact angle hysteresis, and roll-off angle of water droplets on both of these superhydrophobic surfaces with a high speed contact angle meter. The dynamic contact angles and internal velocity distribution of water droplets on superhydrophobic surfaces were studied with a high-speed camera system and a particle image velocimetry (PIV) system, respectively. We found that the acceleration of water droplets when they slide off lotus leaves is greater than that of water droplets sliding off the silicon wafers with microscale pillar structures although the static contact angles of water droplets on lotus leaves are slightly smaller than those on the silicon wafers. The reason is that water droplets sliding off lotus leaves have smaller contact angle hysteresis and larger slip velocities. These results indicate that the dynamic contact angle hysteresis and sliding acceleration of liquid droplets are more suitable for reflecting the hydrophobicity of material surfaces compared with static contact angles. Our experiments also show that lotus leaves with multiscale micro/nanostructures have stronger hydrophobicity and self-cleaning properties compared with the micro-structured superhydrophobic surfaces. droplet, hydrophobicity, contact angle, PIV

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Section: Measurement Of Dynamic Contact Angles and Internal Velocity supporting

confidence: 94%

Study of dynamic hydrophobicity of micro-structured hydrophobic surfaces and lotus leaves

Hao

Yao

Zhang

2011

Sci. China Phys. Mech. Astron.

Self Cite

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“…This can be described by the contact angle hysteresis, defined as the difference between the advancing and receding angle, and the sliding angle where the droplet start to roll off the surface [19]. The kinetics of wetting is much less understood than for droplets in equilibrium, so most of the current theoretical research is focusing on this area [18,20,21]. It is believed that a low contact hysteresis is a requirement of a stable Cassie-Baxter wetting state [22].…”

Section: Theoretical Conceptsmentioning

confidence: 99%

“…The basic principle is to transfer a positive or negative image from a mask by exposing a photoreactive polymer with a UV-, electron-or X-ray source [49]. Due to the wellcontrolled reproducible results, it has mostly been used to create surfaces for examining the superhydrophobic phenomenon and the connections between surface structures and wetting behaviour [12,18,21,23,37,[50][51][52][53][54]. One of the earliest works by Öner et al [18] examined the wetting quantitatively on a micro-textured surface, using photolithography and subsequent etching in silicon to produce three-dimensional pillars with various size, shapes and separations.…”

Section: Photolithographymentioning

confidence: 99%

Surface Nanoengineering Inspired by Evolution

et al. 2011

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Through evolution, nature has optimised structures and materials with a hierarchy from the macro-to the nanoscale. Biological materials are very sophisticated in the way they solve challenges associated with life. Some properties of commercial interest found in nature are selfcleaning, aerodynamic lift, anti-adhesion, water harvesting, water-floating and staying dry. Biomimetics, to learn from nature, has been used for centuries to create new innovative devices. With the use of "nanotools", it is possible to design hierarchical surface structures with exceptional functional properties. In this paper, an overview of interesting surface properties with biomimetic potential, strategies for nanomanipulation of surfaces, potential industrial applications and the potential of using atomistic modelling to optimise surface structuring are discussed.

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“…The channel surface wettability considered includes the contact angle θ channel equal to 70 • , 45 • , 110 • , and 140 • , respectively, corresponding to Case 3-6 shown in Table 1. The associated sliding angle α channel for the channel surface is also considered and obtained from a correlation between the contact angle and the sliding angle widely adopted in the previous studies [33,34], as shown below:…”

Section: Effect Of the Channel Surface Wettabilitymentioning

confidence: 99%

Water Transport and Removal in PEMFC Gas Flow Channel with Various Water Droplet Locations and Channel Surface Wettability

et al. 2018

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Abstract:Water transport and removal in the proton exchange membrane fuel cell (PEMFC) is critically important to fuel cell performance, stability, and durability. Water emerging locations on the membrane-electrode assembly (MEA) surface and the channel surface wettability significantly influence the water transport and removal in PEMFC. In most simulations of water transport and removal in the PEMFC flow channel, liquid water is usually introduced at the center of the MEA surface, which is fortuitous, since water droplet can emerge randomly on the MEA surface in PEMFC. In addition, the commonly used no-slip wall boundary condition greatly confines the water sliding features on hydrophobic MEA/channel surfaces, degrading the simulation accuracy. In this study, water droplet is introduced with various locations along the channel width direction on the MEA surface, and water transport and removal is investigated numerically using an improved model incorporating the sliding flow property by using the shear wall boundary condition. It is found that the water droplet can be driven to the channel sidewall by aerodynamics when the initial water location deviates from the MEA center to a certain amount, forming the water corner flow in the flow channel. The channel surface wettability on the water transport is also studied and is shown to have a significant impact on the water corner flow in the flow channel.

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Sliding of Water Droplets on Microstructured Hydrophobic Surfaces

Cited by 161 publications

References 24 publications

Study of dynamic hydrophobicity of micro-structured hydrophobic surfaces and lotus leaves

Study of dynamic hydrophobicity of micro-structured hydrophobic surfaces and lotus leaves

Surface Nanoengineering Inspired by Evolution

Water Transport and Removal in PEMFC Gas Flow Channel with Various Water Droplet Locations and Channel Surface Wettability

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