From Hygrophilic to Superhygrophobic: Theoretical Conditions for Making High-Contact-Angle Surfaces from Low-Contact-Angle Materials

Langmuir ◽  
2008 ◽  
Vol 24 (14) ◽  
pp. 7573-7579 ◽  
Author(s):  
Abraham Marmur
Keyword(s):  
Contact Angle ◽  
High Contact Angle

Special Wetting Behaviors on Canna Leaf and its Dependence with Microstructures

2013 ◽  
Vol 779-780 ◽  
pp. 64-67
Author(s):  
Xiao Hua Yang ◽  
Jian Hua Xiao ◽  
Jun Fei Ou
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Lotus Leaf ◽  
Micro Scale ◽  
High Adhesion ◽  
Rose Petal ◽  
High Contact Angle ◽  
Wetting Behaviors ◽  
The Rose ◽  
Rose Petal Effect

Like lotus leaf and rose petal, the canna leaf also has excellent super hydrophobicity.The purpose of this paper is to systematically study the super hydrophilicity of canna leaf. Using SEM to observe the morphology of the canna leaf, and analytical balance to measure the adhensive force between water droplet and the leaf . This paper shows that the first type of the canna leaf which has co-exsitence of the nanocrumb and micro-scale convex cells has the high contact angle and low contact angle hysteresis similar to lotus leaf. The another type on the leaf has high contact angle but high adhesion in a certain extent like the rose petal effect, whose microstructure unitarily simple has the micro convex cells, do not distributed anything of nanoscale.

Friction on snow and ice

1953 ◽  
Vol 217 (1131) ◽  
pp. 462-478 ◽  
Keyword(s):  
Experimental Study ◽  
Contact Angle ◽  
Frictional Heating ◽  
Static Friction ◽  
Synthetic Polymers ◽  
Low Friction ◽  
Sliding Speed ◽  
High Contact Angle ◽  
Relative Hardness ◽  
Snow And Ice

An experimental study has been made of the friction of real ski and of smaller models sliding on snow and ice at various temperatures. On cold snow the static friction is high. When the sliding speed is appreciable the friction falls to a low value, and experiments support the view, put forward earlier, that this low friction is due to a localized surface melting produced by frictional heating. Measurements are made on a variety of surfaces including metals, synthetic polymers and waxes. The contact angle which water makes with the surface is important, and there is evidence that this can decrease during sliding. In general, the solids with a high contact angle give a lower friction. The behaviour is also influenced by the relative hardness of ice and of the ski surface at the temperature of sliding. Polytetrafluoroethylene gives a very low friction on snow and ice under all conditions.

CELL CULTURES ON A SUPER WATER-REPELLENT ALKYLKETENE DIMER SURFACE

2006 ◽  
Vol 05 (06) ◽  
pp. 871-876
Author(s):  
HU YAN ◽  
HATSUKI SHIGA ◽  
ETSURO ITO ◽  
KAORU TSUJII
Keyword(s):  
Contact Angle ◽  
Morphological Change ◽  
Cell Cultures ◽  
Experimental Results ◽  
Water Repellent ◽  
Biological Cells ◽  
Special Surface ◽  
Astrocyte Differentiation ◽  
High Contact Angle

The fractal alkylketene dimer (AKD) surface is an artificial super water-repellent one with a high contact angle of 174°, therefore, may provide special surface circumstances for studies of biological cells such as cell cultures. The experimental results indicated that the distribution of F-actin in the astrocytes cultured on the fractal AKD-coated dishes showed the stellate shape, while that in the astrocytes cultured on the poly-L-lysine-coated coverslips showed the formation of long alignment. The morphological change of astrocytes is induced by the fractal AKD surface, and the result suggests that astrocyte differentiation is stimulated by the fractal AKD surface.

scholarly journals DEVELOPMENT OF THE COMPOSITION OF ANTI-SPECIFIC COATING

2019 ◽  
Vol 4 (5) ◽  
pp. 23-27
Author(s):  
В. Логанина ◽  
Valentina Loganina ◽  
С. Кислицына ◽  
Svetlana Kislicyna ◽  
К. Сергеева ◽  
...  
Keyword(s):  
Contact Angle ◽  
Sharp Increase ◽  
Acrylic Resin ◽  
Silicone Resin ◽  
Binder System ◽  
Hydrophobic Properties ◽  
Chlorinated Polyethylene ◽  
Viscosity Increase ◽  
The Matrix ◽  
High Contact Angle

The information about the composition of the anti-icing coating is provided. The use of acrylic resin A-01 and DEGALAN®, highly chlorinated polyethylene resin HCPE and silicone resin SILRES® MSE 100 as a binder is considered. The regularities of changes in viscosity of the composition depending on volume content of the filler – Aerosil brand R 972 are revealed. It is found that the viscosity increase is insignificant when filling in the range 0<φ<0.012. With further filling (φ>0,012) there is a significant change in the ratio of the volume and membranous phases of the matrix, there is a sharp increase in the viscosity of the composition. The optimal volumetric composition of the filler is established for each type of the resin. It is revealed that the interaction in the filler-filler system prevails over the interaction in the filler-binder system. In assessing the hydrophobic properties, it is found that the coatings have a high contact angle (more than 150°), and the roll-off angle does not exceed 10°, which confirms the presence of superhydrophobicity and assumes anti-icing properties of the coatings. The adhesion of the coating to the substrate estimated by the lattice incision method on the mortar and metal substrates is 1 point. Smooth and clear cuts without chipping and cracking are marked at 4x magnification

High contact angle hysteresis of superhydrophobic surfaces: Hydrophobic defects

2009 ◽  
Vol 95 (6) ◽  
pp. 064102 ◽  
Author(s):  
Feng-Ming Chang ◽  
Siang-Jie Hong ◽  
Yu-Jane Sheng ◽  
Heng-Kwong Tsao
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Superhydrophobic Surfaces ◽  
High Contact Angle

scholarly journals Fabrication of Robust Superhydrophobic Bamboo Based on ZnO Nanosheet Networks with Improved Water-, UV-, and Fire-Resistant Properties

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Jingpeng Li ◽  
Qingfeng Sun ◽  
Qiufang Yao ◽  
Jin Wang ◽  
Shenjie Han ◽  
...  
Keyword(s):  
Contact Angle ◽  
Acid Rain ◽  
Modern Society ◽  
Simulated Acid Rain ◽  
High Contact Angle

Bamboo with water-resistant, UV-resistant, and fire-resistant properties was desirable in modern society. In this paper, the original bamboo was firstly treated with ZnO sol and then hydrothermally the ZnO nanosheet networks grow onto the bamboo surface and subsequently modified with fluoroalkyl silane (FAS-17). The FAS-17 treated bamboo substrate exhibited not only robust superhydrophobicity with a high contact angle of 161° but also stable repellency towards simulated acid rain (pH = 3) with a contact angle of 152°. Except for its robust superhydrophobicity, such a bamboo also presents superior water-resistant, UV-resistant, and fire-resistant properties.

Bubble Nucleation on Nanoscopically Smooth Hydrophobic Islands

2008 ◽  
Author(s):  
Youngsuk Nam ◽  
Y. Sungtaek Ju
Keyword(s):  
Contact Angle ◽  
Theoretical Prediction ◽  
Gas Phase ◽  
Indirect Evidence ◽  
Hydrophobic Surface ◽  
Bubble Nucleation ◽  
Dissolved Gas ◽  
Nucleation Barrier ◽  
Long Lifetime ◽  
High Contact Angle

We report our study of an interfacial gas phase formed between a smooth hydrophobic surface and water using pool boiling experiments. Nanoscopically smooth hydrophobic islands of 10 ∼ 100 μm in width are fabricated on a hydrophilic silicon substrate using photolithography. We observe sustained bubble nucleation at superheat as low as 9 °C. The amount of dissolved gas in water does not have a significant effect on bubble nucleation. By comparing the measured minimum superheat for the onset of bubble nucleation with theoretical prediction, we provide indirect evidence for the presence of an interfacial gas phase with widths on the order of 1 μm and contact angle &gt;160°. This high contact angle, which has been postulated to be the reason for the long lifetime of nanobubbles, drastically decreases the nucleation barrier, even on nanoscopically smooth hydrophobic surfaces.

Microfabrication Technologies Based on Electro-Dispensing

2011 ◽  
Author(s):  
Jacqueline Nichols ◽  
Brandon Born ◽  
Emily L. Landry ◽  
Jonathan F. Holzman
Keyword(s):  
Contact Angle ◽  
New Technologies ◽  
Polymer Processing ◽  
Contact Angles ◽  
Beam Focusing ◽  
High Contact Angle ◽  
Electromagnetic Models ◽  
On Chip ◽  
Microfabrication Technology

A microfabrication technology with real-time polymer processing control is introduced in this work. The technique is titled electro-dispensing, as it employs a metal micro-dispensing tip that is biased with a user-defined voltage. The in-situ voltage directs an electric field through the underlying dispensed polymer structure. Polymer droplets are dispensed directly onto a chip with precise (pL) volumes, and the in-situ micro-dispensing tip voltage is varied to adjust the polymer droplet morphology during the microfabrication process. The technique is carried out within a glycerol ambient filler solution, to create an initial high contact angle (160°) on the polymer microdroplets, and voltage tunability is applied to control the microdroplet shapes. Ultraviolet curing is subsequently employed to solidify the micro-spheroid structures on the desired locations across the chip. The electro-dispensing process is demonstrated in this work for numerous microdroplets, with a variety of polymer morphologies and diameters down to 150 μm. The capabilities of the electro-dispensing process are also demonstrated in this work for a specific application relating to integrated photonic circuitry. Polymer microdroplets in the past have been limited to use as lenses for vertical beam focusing (through the plane of the chip), because of their exceedingly low contact angles on solid surfaces. In this work, polymer micro-droplets are introduced for lateral beam focusing and retroreflection (above and parallel to the plane of the chip). These new technologies for on-chip optical beam dispersion management are brought about by the capabilities of electro-dispensing: the use of an ambient filler allows the dispensing process to create high-contact-angle near-spherical microdroplets; the electro-dispensing process then allows this droplet to be tuned for its specific role within the integrated photonic chip (e.g. as a spherical element for in-plane focusing or an elliptical element for in-plane retroreflection). Ray-based analyses and electromagnetic models are used to characterize the optical responses of the micro-spheroid structures, and the results are compared to experimental measurements with on-chip laser beam control.

Sign in / Sign up

Export Citation Format

Share Document