Spectroscopic, transport, and morphological studies of polyaniline doped with inorganic acids

A conducting polymer, polyaniline, was synthesized by chemical polymerization using different inorganic acids, such as HCl, H 2 SO 4 , HClO 4 , HNO 3 , and H 3 PO 4 , as protonic acid media. The synthesized polymers were characterized using UV‐visible and FT‐IR spectroscopy. A granular type of morphology was observed under SEM for HCl, HNO 3 , and H 3 PO 4 doped polyanilines. However, HClO 4 doped polyaniline shows the folded lamellar structure derived from the fibers. The thermal stability of these polymers was investigated with the help of thermogravimetric (TG/SDTA) analysis. The formation of a greater fraction of the conducting emeraldine salt phase is observed in HClO 4 as a protonic acid media. The thermal stability of H 3 PO 4 doped material is found to be better as compared with other acids. An increase in conductivity with an increase in temperature was observed in all the samples except for HClO 4 doped polyaniline. Polym. Eng. Sci. 44:1676–1681, 2004. © 2004 Society of Plastics Engineers.