Polyaniline nanofibers: Syntheses, properties, and applications

Since the discovery that conjugated polymers can be made to conduct electricity through doping [1], a tremendous amount of research has been carried out in the field of conducting polymers [2,3]. Polyaniline (Figure 7.1) is an excellent example of a conjugated polymer that can be tailored for specific applications through the doping process [4]. Since its conducting properties were rediscovered in the early 1980s, polyaniline has been studied for many other potential applications including lightweight battery electrodes [5], electromagnetic shielding devices [6,7], and anticorrosion coatings [8,9]. Bulk polyaniline is now commercially available from several sources [10]. Polyaniline is electrically conductive in its emeraldine oxidation state when doped with a salt that protonates the imine nitrogens on the polymer backbone. Dopants can be added in any desired quantity until all imine nitrogens (half of the total nitrogens) are doped, simply by controlling the pH of the dopant acid solution.