This paper presents results on the development of superhydrophobic nanofiber surfaces for use inseparation of stable water in oil emulsions. Superhydrophobic surfaces are defined as having a watercontact angle exceeding 150°. The most hydrophobic polymer known is PTFE, with a water contactangle of approximately 120°. However, surface wetting properties of polymers can be enhanced bycreating roughness. A simple and inexpensive way to induce surface roughness is to use the technique ofelectrospinning to produce polymeric nanofiber mats. The roughness at the nanoscale of these surfacesenhances surface properties by lowering the surface energy and increases the water contact angle. Usingthe electrospinning technique, three different polymeric nanofiber mats were produced that weresuperhydrophobic : poly(vinylidenefluoride-hexafluoropropylene) (PVDF-HFP), polypropylene, andpoly(4-methyl-1-pentene). Since these surfaces have water contact angles above 150°, water dropletsroll across the surface as near spherical droplets. Experiments were carried out to determine how muchforce was required to move droplets along these surfaces. Due to the high contact angle, water dropletshave low contact area with the surface which reduces the force required to move the droplets along thesurface. It was determined that the force required to move drops along these hydrophobic surfaces wasless than the force of gravity. Since these nanofiber surfaces are porous, they can be used to remove lowconcentrations of water in oil.
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