(682b) Aligned and Oriented Polyaniline Nanofibers

A novel technique to fabricate aligned and oriented nanofibers of polyaniline and its derivatives is reported. The well-ordered and aligned nanostructures are demonstrated through scanning electron microscopy with the diameters of the tips ranging from 20 to 40nm. The aligned nanofibers can be grown onto a very wide variety of substrates including PET, PMMA, polystyrene, PDMS, Teflon, paper, glass, ITO, and Si wafer in a wide variety of sizes. The surfaces coated by aligned polyaniline nanofibers show the property of superhydrophilicity with water contact angle less than 5 degrees. However, after exposure to CF4 plasma, these same surfaces exhibit a dramatic change to superhydrophobicity and water contact angle higher than 175°. We also successfully functionalize the chemical structures of aligned polyaniline nanofibers without destroying the nanostructures. The chemical functionalized method provides us the ability to write directly hydrophobic patterns on the superhydrophilic surfaces. The resulting film show dual responsive surface of superhydrophilicity and hydrophobicity. The method reported here provides a facile, inexpensive technique for forming the architecture of the large arrays of the aligned nanofibers for uses of surfaces of controlled response. This also provides a wide range of applications, e.g., anti-fog surfaces and self-cleaning surfaces, fast responding, chemical sensors, biosensors, DNA stretching, field-emission display, etc.