Photoinduced Formation of Superhydrophobic Surface on Which Contact Angle of a Water Droplet Exceeds 170° by Reversible Topographical Changes on a Diarylethene Microcrystalline Surface

Langmuir ◽  
2012 ◽  
Vol 28 (51) ◽  
pp. 17817-17824 ◽  
Author(s):  
Naoki Nishikawa ◽  
Hiroyuki Kiyohara ◽  
Shingo Sakiyama ◽  
Seiji Yamazoe ◽  
Hiroyuki Mayama ◽  
...  
Keyword(s):  
Contact Angle ◽  
Water Droplet ◽  
Superhydrophobic Surface

Effects of Ambient Air Relative Humidity and Surface Temperature on Water Droplet Spreading Dynamics

2018 ◽  
Author(s):  
M. Jadidi ◽  
M. A. Farzad ◽  
J. Y. Trepanier ◽  
A. Dolatabadi
Keyword(s):  
Contact Angle ◽  
Relative Humidity ◽  
Surface Temperature ◽  
Air Temperature ◽  
Water Droplet ◽  
Superhydrophobic Surface ◽  
High Speed ◽  
Ambient Air ◽  
Dew Point ◽  
Droplet Spreading

Water droplet impact on horizontal glass, aluminum, and superhydrophobic surfaces is experimentally investigated using high speed imaging. Experiments are performed at three different relative humidities (i.e. 10, 20 and 30%) and three surface temperatures (i.e. 20, 2 and −2°C) to ascertain their effects on droplet spreading and recoil behaviors. In this study, the droplet Weber number, Reynolds number, and the ambient air temperature are fixed at 16.2, 1687, and 23°C, respectively. The high-speed images of impact, spreading and recoil of the droplets as well as the temporal variations of droplet spreads are prepared. Results show that the ratio of surface temperature to dew point temperature (which depends on the air temperature and relative humidity) has a significant influence on droplet spreading, recoil, and contact angle. When this ratio is less than one, condensation and frost formation become important. Decreasing the mentioned ratio (it can be done by decreasing the surface temperature or increasing the relative humidity) causes the droplet spreading factor for hydrophilic surfaces to increase significantly. For superhydrophobic surface, decreasing this ratio (within the mentioned range) does not influence the maximum spreading. However, the recoiling phase is slowed down and the droplet detachment time form the superhydrophobic surface is increased noticeably. In addition, the equilibrium contact angle decreases as the mentioned ratio decreases.

A biomimetic surface with switchable contact angle and adhesion for transfer and storage of microdroplets

Nanoscale ◽  
2018 ◽  
Vol 10 (32) ◽  
pp. 15393-15401 ◽  
Author(s):  
Hanpeng Gao ◽  
Yan Liu ◽  
Shuyi Li ◽  
Guoyong Wang ◽  
Zhiwu Han ◽  
...  
Keyword(s):  
Contact Angle ◽  
Corrosion Resistance ◽  
Superhydrophobic Surface ◽  
Good Stability ◽  
Biomimetic Surface ◽  
And Storage

The as-prepared superhydrophobic surface has a switchable contact angle and adhesion with good stability and corrosion resistance.

scholarly journals Superhydrophobic textile: treatment in aqueous solutions of aluminum salts

2021 ◽  
Author(s):  
Eterina Endiiarova ◽  
Artem Osipov ◽  
Sergey Alexandrov ◽  
Alexander Shakhmin
Keyword(s):  
Contact Angle ◽  
Photoelectron Spectroscopy ◽  
Superhydrophobic Surface ◽  
Hydrophobic Surface ◽  
Solution Concentration ◽  
Textile Processing ◽  
X Ray ◽  
Textile Materials ◽  
Aluminum Salts ◽  
Processing Treatment

Abstract Textile is currently a promising material. Obtaining hydrophobic surfaces on textiles significantly increases its value when used in various fields. In this work we carried out experiments on textile processing. Treatment of textile materials in solutions containing aluminum allows to obtain a superhydrophobic surface. KAl(SO4) and AlCl3 solutions were used. It was found that treatment in AlCl3 solution is more effective and allows to achieve a hydrophobic surface on textile with a contact angle of more than 150º. The hydrophobic surface retained its properties even after 30 days. Textile samples were investigated using X-Ray photoelectron spectroscopy (XPS). The X-Ray photoelectron spectroscopy results showed hydrophobicity in the treatment of textile materials is ensured by the formation of aluminum oxide on the surface. The dependence of the coarse calico contact angle on the AlCl3 solution concentration is determined. which demonstrates that when the concentration of AlCl3 solution increases (within the limits of variation considered), the contact angle also increases.

A Tool to Determine the Hydrophobicity of Insulators using Contact Angle of a Water Droplet

2021 ◽  
Author(s):  
Supun Amarathunga ◽  
Lochana Ranathunga ◽  
Prabath Lakmal ◽  
Dimuth Saranga ◽  
Rasara Samarasinghe ◽  
...  
Keyword(s):  
Contact Angle ◽  
Water Droplet

Numerical Study of a Small Droplet Movement in a Microchannel under Heat Source

2019 ◽  
Vol 894 ◽  
pp. 104-111
Author(s):  
Thanh Long Le ◽  
Jyh Chen Chen ◽  
Huy Bich Nguyen
Keyword(s):  
Contact Angle ◽  
Heat Source ◽  
Water Droplet ◽  
Stokes Equations ◽  
Numerical Study ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Initial Position ◽  
Immiscible Fluids ◽  
Two Phase

In this study, the numerical computation is used to investigate the transient movement of a water droplet in a microchannel. For tracking the evolution of the free interface between two immiscible fluids, we employed the finite element method with the two-phase level set technique to solve the Navier-Stokes equations coupled with the energy equation. Both the upper wall and the bottom wall of the microchannel are set to be an ambient temperature. 40mW heat source is placed at the distance of 1 mm from the initial position of a water droplet. When the heat source is turned on, a pair of asymmetric thermocapillary convection vortices is formed inside the droplet and the thermocapillary on the receding side is smaller than that on the advancing side. The temperature gradient inside the droplet increases quickly at the initial times and then decreases versus time. Therefore, the actuation velocity of the water droplet first increases significantly, and then decreases continuously. The dynamic contact angle is strongly affected by the oil flow motion and the net thermocapillary momentum inside the droplet. The advancing contact angle is always larger than the receding contact angle during actuation process.

scholarly journals Preparation of Superhydrophobic Steel Surfaces with Chemical Stability and Corrosion

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 398 ◽  
Author(s):  
Chongwei Du ◽  
Xiaoyan He ◽  
Feng Tian ◽  
Xiuqin Bai ◽  
Chengqing Yuan
Keyword(s):  
Contact Angle ◽  
Corrosion Resistance ◽  
Carbon Steel ◽  
Chemical Stability ◽  
Superhydrophobic Surface ◽  
Contact Angle Hysteresis ◽  
Water Contact ◽  
Simple Method ◽  
Q235 Carbon Steel ◽  
Steel Surfaces

Corrosion seriously limits the long-term application of Q235 carbon steel. Herein, a simple fabrication method was used to fabricate superhydrophobic surfaces on Q235 carbon steel for anticorrosion application. The combination of structure and the grafted low-surface-energy material contributed to the formation of superhydrophobic steel surfaces, which exhibited a water contact angle of 161.6° and a contact angle hysteresis of 0.8°. Meanwhile, the as-prepared superhydrophobic surface showed repellent toward different solutions with pH ranging from 1 to 14, presenting excellent chemical stability. Moreover, the acid corrosive liquid (HCl solution with pH of 1) maintained sphere-like shape on the as-prepared superhydrophobic surface at room temperature, indicating superior corrosion resistance. This work provides a simple method to fabricate superhydrophobic steel surfaces with chemical stability and corrosion resistance.

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