Nanostructured polyaniline synthesized using interface polymerization and its redox activity in a wide pH range

Purely nanostructured polyaniline with the conductivity of 7.2 S cm−1 was synthesized via the quick addition of the oxidant of the solid ammonium peroxydisulfate into a cooled solution containing aniline and hydrochloric acid without any templates. The morphology of polyaniline is constructed of interwoven fibers with an average diameter of about 50 nm with lengths varying from 250 nm to 370 nm. In general, the conventional polyaniline completely lost its electric activity including conductivity and redox activity at pH 6; however, the polyaniline reported here shows two pairs of redox peaks on its cyclic voltammogram in 1.0 M NaCl solution with pH 7.0, which is similar to that of the conventional polyaniline in the more acidic solutions; and it still holds the redox activity until pH 9.0. The pH dependence of conductivity of polyaniline is also improved compared to that of the conventional polyaniline. The ESR measurements show that the deprotonated polyaniline still holds rather high unpaired spin densities. The 1H NMR spectra of polyaniline synthesized using interface polymerization are different those of the conventional polyaniline. The electrochemical behavior and spectra of polyaniline synthesized via the quick addition of an oxidant solution into a solution of aniline were reported and discussed.