The Design of Superhydrophobic Surfaces

CNT Carbon nanotubes CVD Chemical vapor deposition DRIE Deep reactive ion etching EBL Electron beam hthography LbL Layer-by-layer self-assembly PANI Polyanihne PDMS Polydimethylsil oxane PS Polystyrene PVA poly(vinyl alcohol) 

Templating techniques rephcate a pattern or shape, allowing the inverse of the original pattern to be produced, for example, by either two- or three-dimensional printing, pressing or growing a structure against the voids of 

Colloidal lithography is another technique of interest, as the process incorporates the use of soluble particles as removable templates. Recent 

Inspired by the intriguing hierarchical structures formed on the lotus leaf, electrospinning is a highly versatile technique that allows the continuous fabrication of synthetic and natural polymers, nanoparticles, metals, and 

Self-assembly and layer-by-layer (LbL) assembly are convenient and economical methods to produce superhydrophobic surfaces. These methods 

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As we have shown, a combination of wetting and roughness provides many new and very special hydrodynamic properties of surfaces, which could be explored with the formalism discussed here. This should allow the local slip tensors to be determined by global measurements, such as the permeability of a textured channel as a function of the surface orientations or the hydrodynamic force exerted on the body approaching superhydrophobic plates. They may also guide the design of superhydrophobic surfaces for microfluidic lab-on-a-chip and other applications. 

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

The power of the tensor formalism and the concept of effective slippage have then been demonstrated by exact solutions for two other potential applications optimization of transverse flow and anal3Aical results for hydrodynamic resistance to the approach of two surfaces. These examples demonstrate that properly designed superhydrophobic surfaces could generate a very strong transverse flow and significantly reduce the so-called "viscous adhesion." Finally, we have discussed how superhydrophobic surfaces could amplify electro kinetic pumping in microfluidic devices. 

The wettability of a particular substrate/film depends both on the chemical composition and the surface structure. Thus, the preparation of superhydrophobic coatings requires low-surface-energy functional groups such as fluorinated groups [209] and an appropriate surface topography [210,211]. As has been depicted already in the previous applications, a thorough design of a polymer blend can fulfill both requirements. 

The lotus effect has inspired scientists to design superhydrophobic surfaces for applications such as self-cleaning windows and water-repellent clothing. To understand the lotus effect and other phenomena involving liquids and solids, we must understand intermoiecuiar forces, the forces that exist between molecules. Only by understanding the nature and strength of these forces can we understand how the composition and structure of a substance are related to its physical properties in the liquid or solid state. 

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