Water-Repellent Stability of Superhydrophobic Materials under Hydrostatic Pressure

2014 ◽  
Vol 633-634 ◽  
pp. 764-768
Author(s):  
Jian Ye Huang ◽  
Feng Hui Wang
Keyword(s):  
Hydrostatic Pressure ◽  
Superhydrophobic Surface ◽  
Hierarchical Structures ◽  
Water Repellency ◽  
Total Reflection ◽  
Wetting Transition ◽  
Water Repellent ◽  
Lotus Leaf ◽  
Stability Of Water ◽  
Air Film

Keeping the water-repellent stability of superhydrophobic surface is necessary in application. Based on the total reflection of Cassie interface and vacuum technique, the superhydrophobic stability of the lotus leaf and an artificial material was investigated. The results show that during the Cassie-Wenzel transition, primary wetting transition occurs at a certain pressure that in accordance with theoretical prediction. However, when the air film is entrapped between microstructures, stability of water-repellency was greatly enhanced, and part of the wetting transition can be recovered when the pressure was released. Due to the micro-and nanoscale hierarchical structures, the lotus leaf shows better water-repellent stability and dewetting property than the artificial superhydrophobic surface when the hydrostatic pressure was applied and released.

Contrasting water adhesion strengths of hydrophobic surfaces engraved with hierarchical grooves: lotus leaf and rose petal effects

Nanoscale ◽  
2017 ◽  
Vol 9 (42) ◽  
pp. 16200-16204 ◽  
Author(s):  
Zhengqing Zhang ◽  
Man Yeong Ha ◽  
Joonkyung Jang
Keyword(s):  
Molecular Dynamics ◽  
Superhydrophobic Surface ◽  
Wetting Transition ◽  
Hydrophobic Surfaces ◽  
Lotus Leaf ◽  
Water Adhesion ◽  
Rose Petal

Molecular dynamics study on the (de)wetting transition of hierarchical grooves engraved on a superhydrophobic surface.

Fabrication of a Micro/Nano Integrated Roughened Structure Using Nanosphere Lithography (NSL)

2004 ◽  
Author(s):  
Abel L. Thangawng ◽  
Junghoon Lee
Keyword(s):  
Plasma Etching ◽  
Superhydrophobic Surface ◽  
Design Procedure ◽  
Nanosphere Lithography ◽  
Experimental Results ◽  
Water Repellent ◽  
Fabrication Technology ◽  
Lotus Leaf ◽  
Double Structure ◽  
On Chip

This paper presents a fabrication technology to create a double roughened PDMS structure for a superhydrophobic surface. The fabricated surface has many application potentials, including on-chip micro liquid processor and water repellent coating. Similar structure can be found in nature on a lotus leaf (Fig. 1.) Due to its superhydrophobic surface, lotus leaf repels water and in the process performs self-cleaning [1]. In this paper, we show the combination of Nanosphere Lithography (NSL), plasma etching, and molding technique to create the micro/nano integrated double structure using PDMS. Also described is the design procedure and experimental results for the double-structured superhydrophobic surface.

Design of Lotus-Leaf-Like Decoration Materials

2012 ◽  
Vol 450-451 ◽  
pp. 881-884
Author(s):  
Rui Hong Wu
Keyword(s):  
Raw Materials ◽  
Organization Structure ◽  
Water Repellency ◽  
Structure Stability ◽  
Water Repellent ◽  
Interior Decoration ◽  
Lotus Leaf ◽  
Wrinkle Resistance ◽  
Fine Fiber ◽  
Nano Coating

Lotus leaf structures shows shelf-cleaning properties of water-repellent, it’s convenient to clean, especially the interior decoration materials. Polyester sea-island ultra-fine fiber was chosen as raw materials, the crepe weave was used as the organization structure, and finally through water-repellent nano-coating finishing to form a Lotus leaf-like surface, then the water repellency, the anti-fouling performance and the anti-ultraviolet performance of lotus-leaf-like materials was tested and analyzed. The conclusions drawn are as follows: the water repellency, the anti-fouling performance and the anti-ultraviolet performance of lotus-leaf-like decoration materials was excellent, the UV transmission of the materials was only 2%, which was far below the International standard and at the same time the results shows that the materials had good wrinkle resistance property, it can improve the structure stability.

scholarly journals Superrepellency of underwater hierarchical structures on Salvinia leaf

2020 ◽  
Vol 117 (5) ◽  
pp. 2282-2287 ◽  
Author(s):  
Yaolei Xiang ◽  
Shenglin Huang ◽  
Tian-Yun Huang ◽  
Ao Dong ◽  
Di Cao ◽  
...  
Keyword(s):  
Extreme Environments ◽  
Hierarchical Structures ◽  
Complete Recovery ◽  
Superhydrophobic Surfaces ◽  
Water Repellent ◽  
Salvinia Molesta ◽  
Wenzel State ◽  
Water Filling ◽  
Lotus Leaves ◽  
Air Film

Biomimetic superhydrophobic surfaces display many excellent underwater functionalities, which attribute to the slippery air mattress trapped in the structures on the surface. However, the air mattress is easy to collapse due to various disturbances, leading to the fully wetted Wenzel state, while the water filling the microstructures is difficult to be repelled to completely recover the air mattress even on superhydrophobic surfaces like lotus leaves. Beyond superhydrophobicity, here we find that the floating fern, Salvinia molesta, has the superrepellent capability to efficiently replace the water in the microstructures with air and robustly recover the continuous air mattress. The hierarchical structures on the leaf surface are demonstrated to be crucial to the recovery. The interconnected wedge-shaped grooves between epidermal cells are key to the spontaneous spreading of air over the entire leaf governed by a gas wicking effect to form a thin air film, which provides a base for the later growth of the air mattress in thickness synchronously along the hairy structures. Inspired by nature, biomimetic artificial Salvinia surfaces are fabricated using 3D printing technology, which successfully achieves a complete recovery of a continuous air mattress to exactly imitate the superrepellent capability of Salvinia leaves. This finding will benefit the design principles of water-repellent materials and expand their underwater applications, especially in extreme environments.

Non-adhesive lotus and other hydrophobic materials

2008 ◽  
Vol 366 (1870) ◽  
pp. 1539-1556 ◽  
Author(s):  
David Quéré ◽  
Mathilde Reyssat
Keyword(s):  
Solid Surface ◽  
Room Temperature ◽  
Water Repellency ◽  
Short Review ◽  
Water Repellent ◽  
Practical Applications ◽  
Hydrophobic Materials ◽  
Volatile Liquid ◽  
Air Cushion ◽  
The Stability

Superhydrophobic materials recently attracted a lot of attention, owing to the potential practical applications of such surfaces—they literally repel water, which hardly sticks to them, bounces off after an impact and slips on them. In this short review, we describe how water repellency arises from the presence of hydrophobic microstructures at the solid surface. A drop deposited on such a substrate can float above the textures, mimicking at room temperature what happens on very hot plates; then, a vapour layer comes between the solid and the volatile liquid, as described long ago by Leidenfrost. We present several examples of superhydrophobic materials (either natural or synthetic), and stress more particularly the stability of the air cushion—the liquid could also penetrate the textures, inducing a very different wetting state, much more sticky, due to the possibility of pinning on the numerous defects. This description allows us to discuss (in quite a preliminary way) the optimal design to be given to a solid surface to make it robustly water repellent.

Controllable fabrication of lotus-leaf-like superhydrophobic surface on copper foil by self-assembly

2014 ◽  
Vol 116 (4) ◽  
pp. 1613-1620 ◽  
Author(s):  
Zhiqing Yuan ◽  
Xian Wang ◽  
Jiping Bin ◽  
Menglei Wang ◽  
Chaoyi Peng ◽  
...  
Keyword(s):  
Self Assembly ◽  
Superhydrophobic Surface ◽  
Copper Foil ◽  
Lotus Leaf ◽  
Controllable Fabrication

scholarly journals Superhydrophobicity in perfection: the outstanding properties of the lotus leaf

2011 ◽  
Vol 2 ◽  
pp. 152-161 ◽  
Author(s):  
Hans J Ensikat ◽  
Petra Ditsche-Kuru ◽  
Christoph Neinhuis ◽  
Wilhelm Barthlott
Keyword(s):  
Chemical Composition ◽  
Water Repellency ◽  
Contact Angles ◽  
Dense Layer ◽  
Lotus Effect ◽  
Nano Structure ◽  
Lotus Leaf ◽  
Water Drops ◽  
The Impact ◽  
Unique Chemical

Lotus leaves have become an icon for superhydrophobicity and self-cleaning surfaces, and have led to the concept of the ‘Lotus effect’. Although many other plants have superhydrophobic surfaces with almost similar contact angles, the lotus shows better stability and perfection of its water repellency. Here, we compare the relevant properties such as the micro- and nano-structure, the chemical composition of the waxes and the mechanical properties of lotus with its competitors. It soon becomes obvious that the upper epidermis of the lotus leaf has developed some unrivaled optimizations. The extraordinary shape and the density of the papillae are the basis for the extremely reduced contact area between surface and water drops. The exceptional dense layer of very small epicuticular wax tubules is a result of their unique chemical composition. The mechanical robustness of the papillae and the wax tubules reduce damage and are the basis for the perfection and durability of the water repellency. A reason for the optimization, particularly of the upper side of the lotus leaf, can be deduced from the fact that the stomata are located in the upper epidermis. Here, the impact of rain and contamination is higher than on the lower epidermis. The lotus plant has successfully developed an excellent protection for this delicate epistomatic surface of its leaves.

Performance Study of Nano-TiO2 Modified Fabric

2012 ◽  
Vol 549 ◽  
pp. 733-736
Author(s):  
Xiao Mian Chen ◽  
Jing Jing Shi ◽  
Hong Sha Su ◽  
Chun Ting Lin ◽  
En Long Yang
Keyword(s):  
Titanium Dioxide ◽  
Catalytic Activity ◽  
Catalytic Properties ◽  
Antibacterial Property ◽  
Wear Behavior ◽  
Water Repellency ◽  
Innovative Technology ◽  
Water Repellent ◽  
High Catalytic Activity ◽  
Performance Study

The catalytic properties of nano-TiO2 modified fabric suits the demand for self-cleaning in recent years. In this paper, advanced and innovative technology were used to synthesize water sol of titanium dioxide photocatalyst with high catalytic activity for fabric finishing. The wear behavior, antibacterial property and water repellency of treated and untreated fabric were tested. Results indicate that finishing and washing of the titanium dioxide had no effect on wear behavior; finished and washed fabric has a certain antibacterial and water repellent properties.

scholarly journals Water repellency of clay, sand and organic soils in Finland

2008 ◽  
Vol 16 (3) ◽  
pp. 267 ◽  
Author(s):  
K. RASA ◽  
R. HORN ◽  
M. RÄTY
Keyword(s):  
Preferential Flow ◽  
Management Practice ◽  
Soil Surface ◽  
Water Repellency ◽  
Organic Soil ◽  
Water Infiltration ◽  
Organic Soils ◽  
Water Repellent ◽  
Moisture Regime ◽  
Wetting Process

Water repellency (WR) delays soil wetting process, increases preferential flow and may give rise to surface runoff and consequent erosion. WR is commonly recognized in the soils of warm and temperate climates. To explore the occurrence of WR in soils in Finland, soil R index was studied on 12 sites of different soil types. The effects of soil management practice, vegetation age, soil moisture and drying temperature on WR were studied by a mini-infiltrometer with samples from depths of 0-5 and 5-10 cm. All studied sites exhibited WR (R index >1.95) at the time of sampling. WR increased as follows: sand (R = 1.8-5.0) < clay (R = 2.4-10.3) < organic (R = 7.9-undefined). At clay and sand, WR was generally higher at the soil surface and at the older sites (14 yr.), where organic matter is accumulated. Below 41 vol. % water content these mineral soils were water repellent whereas organic soil exhibited WR even at saturation. These results show that soil WR also reduces water infiltration at the prevalent field moisture regime in the soils of boreal climate. The ageing of vegetation increases WR and on the other hand, cultivation reduces or hinders the development of WR.;

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