Electrospinning and Superhydrophobic Materials

Many processes are affected by the interaction of liquids with surfaces. These interactions depend on the solid-liquid, solid-vapour, and liquid-vapour surface tensions, as well as the surface structure or roughness. A liquid in intimate contact with a rough surface will generally be better adhered than the same liquid on a smooth surface due to the increase in the contact area. Rough superhydrophobic surfaces with low surface energy, however, support the liquid on the peaks of the roughness, with minimal contact area, and as a consequence the liquid is easily removed. In this work durable micron sized polyurethane fibres were produced byelectrospinning. The surface of these fibre mats was microscopically rough, and nano-scale features were added to the fibre surface by electrospinning with nanoparticles, or through a fluorinated alkyl silane, sol-gel coating process. The sol-gel treatment produced a rough hydrophobic coating on the electrospun fibres. From contact angle measurements, it was found that these methods increased the water contact angle, however, a truly superhydrophobic surface with small tilt angle was only achieved when a thicker sol-gel coating was deposited on the electrospun fibre mats.