Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

Abstract

The terms superhydrophobicity and superhydrophilicity were introduced not very long ago, in 1996 and 2000, respectively.The former is used to describe exceptionally weak and the latter used to indicate strong interactions of materials and IntroductionAfter more than two centuries of research, capillarity and wetting phenomena still remain popular topics of investigation in many modern surface chemistry laboratories. Curiosity and fascination with rain droplets splashing in a puddle, water droplets decorating flowers, leaves of plants and fruits after rain or watering and colorful soap bubbles shaped at the end of wheat straw have never been stronger and go beyond scientific laboratories. Colorful images of liquid droplets and puddles, illustrating their behavior on a variety of surfaces, thrive in professional journals, popular magazines and Internet. However, terms such as wetting, spreading and contact angle are still puzzling to the layman and beginner researcher. To facilitate

Direct Measurements of Adhesion Forces for Water Droplets in Contact with Smooth and Patterned Polymers

“…[1][2][3] In addition, many engineering inventions rely on liquid-solid interactions, including inkjet printing, 4 biosurfactant transport in agricultural soil, 5 froth flotation of particles 6,7 and many other applications. [8][9][10][11] By grasping the mechanism that governs liquid-solid interactions, solid surfaces can be designed and fabricated to meet demands in industrial applications, such as slippery superhydrophobic surfaces for self-cleaning, 12,13 anti-icing, [14][15][16] drag reduction 13 and enhanced condensation, 17 sticky superhydrophobic surfaces for liquid capturing, [18][19][20] superhydrophobic fabric for water and dirt resistance, 21 superhydrophilic surfaces for boiling 22 and water collection 23 and other surfaces. 24 Adhesion force measurement is an effective way to quantify the interactions between liquid and solid surfaces.…”

“…8,9,[37][38][39] Li et al 40 studied the correlation between water adhesion to patterned surfaces made of micropillars and micropores and receding contact angles. They directly observed the dynamics of the receding contact line and analyzed local contact angles on single micropillars.…”

Superlyophilic Interfaces and Their Applications

“…[137] For example, by creating a SHPL coating consisting of TiO 2 and SiO 2 , a general and cost-effective strategy was developed for electrostatic powder coating on insulating substrates. Water droplets can spread completely and join together to form continuous ultra-thin water film that is temporarily conductive, thus electrostatic powder coatings can be successfully operated.…”

Fabrication of superhydrophobic zirconium surface with a facile electrodeposition process

“…Such effect is named superhydrophobicity, wherein the surface water (advancing) contact angle (CA) is larger than 150°and the sliding angle (SA) is smaller than 10°. 3,4 A rough surface microstructure and a low surface energy composition, [3][4][5][6] on the whole, are indispensable for the creation of superhydrophobicity. Until now, general means for fabrication of superhydrophobic surface include sol-gel processing, 7,8 anodic oxidation, 9,10 spray deposition, 11 chemical etching, [12][13][14][15][16] electrospinning 17,18 and so on.…”