Influence of oxidation state, pH, and counterion on the conductivity of polyaniline

Abstract

The resistivity of electrochemically synthesized polyaniline films was measured with the films submerged in electrolyte. The resistivity was found to depend on the redox state of the film, the pH of the solution and, to a lesser extent, on the type of anion present. The resistivity at a given pH is low but only inside a narrow potential window. The width of this window decreases with increasing pH and vanishes at pH 6. The walls of the potential window correlate roughly with the formal potentials of the redox processes as determined by cyclic voltammetry. It has been shown that the resistivity of polyaniline depends on its moisture content. For the wet polymer a small degree of protonation is apparently sufficient to cause a decrease in resistivity of more than 6 orders of magnitude. This behavior may be rationalized by assuming that, in the presence of water, the charge transport mechanism involves proton exchange reactions as well as intermolecular electron transport.

Polyaniline Conducting Electroactive Polymers Thermal and Environmental Stability Studies

“…The conductivity of polyaniline, unlike all other conducting polymers depends on two variables, namely the degree of oxidation (electrochemical doping) and the degree of protonation (acid doping) of the material 28 . To a lesser extent, it is also dependent on the type of anion present 29 . However, It has been found that the nature of anion can have an important effect on the properties and molecular structure of the polymer 30 .…”

Characterization of Electrochromic Properties of Polyaniline Thin Films Electropolymerized in H<sub>2</sub>SO<sub>4</sub> Solution

“…The conductivity of PANI films mainly depends on the oxidation state, pH of the electrolyte and the type of dopant used for protonation [11]. PANI exhibits reverse electrochromic performance; it is able to switch from a transparent yellow state to a green one, according to reduction and oxidation processes [12].…”

Polysaccarides-based gels and solid-state electronic devices with memresistive properties: Synergy between polyaniline electrochemistry and biology

“…Concentrations of acetic acid higher than 30% w/w were not considered, because they induced over-oxidation of PANI and chitosan depolymerization, as the gel softening showed, according to literature. 31,32 Thus, we can conclude that chitosan-gel, although it has a good biocompatibility, is not able to preserve the PANI conductivity without adding of strong acid.…”