Artificial superhydrophobic surfaces

Very similar results were also reported by Oner and McCarthy [63], who found that their 8x8 [un square pillar array surface (height 40 pm) was in flie Wenzel state when the pitch is 56 pm. For 8x8 pm square pillar array with pitches 32 pm, Oa is essentially constant at 174°. On the other hand, 0r is shown to decrease as the pitch decreases. The result is attributed to the increase in contact line length per unit area. Water pins at the edge of the pillar top, the smaller the pitch, the longer the contact line per unit area, the smaller the 0r. This interpretation is supported by studying the 0r values of pillar array surface with different pillar geometry. 

---

Furstner R, Barthlott W, Neinhuis C, Walzel P (2005) Wetting and self-cleaning properties of artificial superhydrophobic surfaces. Langmuir 21 956-961... 

In recent years, due to a plethora of potential applications of superhydro-phobicity in daily life, many elforts have been taken to fabricate artificial superhydrophobic surfaces. Depending on the application and material, different methods have been employed to create superhydrophobic smfaces [8], Most of these methods involve either creating a micro/ nano-structme on an inherently hydrophobic material [9,10] or treating a specific micro/nano-structure with a hydrophobic coating [11-14]. For instance, for metallic materials, roughened surfaces have to be coated with low surface energy materials. 

Artificial superhydrophobic surfaces have been introduced in the past decade and a variety of production methods (self-assembly, lithography, sol-gel) and materials (polymers, metals, Si, etc.) have been suggested. 

Bhushan, B., Jung,Y.C., Koch, K., 2009. SelKcleaning efficiency of artificial superhydrophobic surfaces. Langmuir 25, 3240. 

Bhushan, B.,Jung,Y.C., 2008. Wetting, adhesion and friction of superhydrophobic and hydrophilic leaves and fabricated micro/nanopatterned surfaces. J. Phys. Condens. Matter 20. Bhushan, B., Jung,Y.C., Koch, K., 2009. Self-cleaning efficiency of artificial superhydrophobic surfaces. Langmuir 25, 3240. 

The artificial design of superhydrophobic and seif-cleaning surfaces has become an extremely active area of fundamental and applied research. 

Bhushan, B., and Jung, Y. C. 2010. Natural and biomimetic artificial surfaces for superhydrophobicity, self-cleaning, low adhesion, and drag rednction. Prog. Mater. Sci. 56 1. 

---