Superhydrophobic coating plasma

For deposition of hydrophobic coatings, a mixture of CHVHe gases was used in the plasma. Superhydrophobic coatings were created with a Cp4/H2/He plasma. The deposited coatings were analyzed with PM-RAIRS, x-ray photoelectron spectroscopy, scanning electron microscopy (SEM, JEOL 6700 F - FESEM), atomicforce microscopy (AFM, Molecular Imaging SPM microscope with RHK controllers), ellipsometiy, and water contact angle measurements. 

Figure 8. PM-RAIRS andXPS (inset) of superhydrophobic coatings deposited with scanning CF4/H2/He plasma (rf power = 300 W). The number of plasma treatments is indicated in the figure. (9)...

Figure 1. Schematic for producing a superhydrophobic coating on device surfaces using oxygen plasma treatment, (a) The surface of the device is coated with a layer of fluoropolymer (Teflon), (b) Oxygen plasma treatment is used to roughen the surface of fluoropolymer. (c) A superhydrophobic surface is obtained after the oxygen plasma treatment.

Lee, J.-H., Lee, S.H., Kim, D., Park,Y.S., 2013a. The structural and surface properties of carbon nanotube synthesized by microwave plasma chemical vapor deposition method for superhydrophobic coating.Thin Solid Films 546, 94. 

Cellulose based ultrafine fibers with superhydrophobicity have been prepared. Park et al. [115] electrospim cellulose triacetate fibers using methylene chloride/ethanol as the solvent system and further converted the fiber mat to be superhydrophobic by plasma treatment. Another method using sol-gel coating to converting cellulose acetate fiber mats fi om superhydrophilicity to superhydrophobicity was done by Ding et al. [116]. The resultant superhydrophobic fiber mats are useful for many potential applications such as self-cleaning materials and contamination prevention, due to their poor wettability. 

Here we describe two simple fabrication processes to modify the surface of the device to achieve a very high water contact angle. In the first approach, the device was first coated with a thin film of hydrophobic materials, fluoropolymer in this case, and then oxygen plasma was used to create superhydrophobic surfaces. However, only in some cases, the chemical properties of the hydrophobic materials could be altered by the oxygen plasma treatment [19]. Therefore, a second technique has been developed where the nanostructures can be created on the device surfaces by a nanoimprint process [20]. Both of these approaches are compatible with the micro-fabrication process. 

In summary, we have developed two techniques to impart superhydrophobic property to the surfaces of devices. In the first approach, oxygen plasma treatment was used to roughen the Teflon coating whose surface water contact angle could be tuned form 120° to 168° by varying the oxygen plasma treatment time. However, the application of the oxygen plasma process is limited to fluoropolymers. In the second approach, nanoimprint process was used to create nanostructures on the... 

Gleason and coworkers have demonstrated that the surface coating of carbon nanotubes (CNTs) by hot filament CVD of tetrafluoroethylene and by plasma enhanced CVD of MMA provide surface-modified CNTs having a stable/ superhydrophobic surface and good compatibility with PMMA, respectively [91, 92]. The superhydrophobic CNT indicated superior water repellency, whereby essentially spherical and micrometer-sized water droplets were suspended on top of the nanotube forest. The multiwall-CNT/PMMA nanocomposites were dispersed into PMMA via melt mixing. The orientation of CNT in the blend was achieved by melt drawing. The dispersed CNT in the blend indicated a significant effect on mechanical properties of the blend even at a 1% concentration of CNT. 

Liu et al. (2012) have recently proposed a sol-gel coating formed by silica containers doped with octadecylamine (ODA) and coated with dopamine-ODA, while tetraethoxysilane was used as cross-linker for the coating network. The developed coating has shown that, after removal of the surface hydrophobic layer (ODA) with O2 plasma, the system becomes first hydrophilic (due to the suppression of the surface hydro-phobic layer) but with time and high relative environmental humidity the coating again becomes superhydrophobic due to release of encapsulated ODA, as measured by contact angle measurements (shown in... 

Tsuruta, S., Morimoto, K., Hirotsu,T., Suzuki, H., 2006. Superhydrophobic phenomena on three-dimensional surface structures coated with plasma polymtt.Jpn. J. Appl. Phys. Part 1 Regular Papers and Short Notes and Review Papers 45, 8502. 

Stability attributed to the presence of long and thin nanohairs on the fibers (Shin et al., 2012). In another example, inherent microstructure of cellulose paper was enhanced by plasma-assisted nanostructuring to create a surface that once coated with a thin fluorocarbon film was superhydrophobic (Balu et al., 2008).The nanotopography was varied with plasma treatment, yielding a surface in either the Wenzel or Cassie—Baxter states. 

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