Wormlike Acid-Doped Polyaniline: Controllable Electrical Properties and Theoretical Investigation

Polyaniline doped with hydrochloride acid was prepared via a chemical oxidative polymerization between APS oxidant and aniline monomer in hydrochloric acid solution with different concentrations. The diameter of each PANI wormlike nanorod is fairly uniform, and the diameter of PANI nanorod decreases with increase in concentration of HCl. For the degradation stage of the polymeric backbone, the rate of degradation increases with decrease in the HCl concentration, which means the samples synthesized in higher HCl concentration possess the more stable structures. The highest conductivity of 1.04 S/cm is achieved when HCl concentration is 1.0 mol/L, which generated uniformly branched knobbles with good dispersion and higher aspect ratio. The variation tendency of complex permittivity keeps coordinate with the conductivity. First-principles calculations verified that N(E) of PANIs in the protonated states are larger than that of the unprotonated PANI, which means that the conductivity is promoted by the interaction between PANI and doping hydrochloric acid through protonation. Furthermore, the N(E) of protonated PANIs increases as the ratio of protonic acid increases, which means that the increase of protonic acid ratio is conducive to the enhancement of the electronic conductivity of PANI.