Pyrolysis–gas chromatography/mass spectrometry applied to the identification of different states of polyaniline

Abstract

Pyrolysis-gas chromatography/mass spectrometry (Py-CG/MS) has been applied to study and compare the composition of two electrochemically synthesized polyaniline (PANI) forms: fully reduced leucoemeraldine (LE) and intermediately oxidized emeraldine (EM). The different PANI forms were electrochemically synthesized using cyclic voltammetry. They were dedoped by stirring for 24 h in ammoniacal solutions. Leucoemeraldine and emeraldine pyrograms presented differences in the relative intensity of their fragment signals. Emeraldine pyrograms presented a higher relative intensity of the signals associated to oxidized fragments (i.e. quinone imine) than leucoemeraldine pyrograms. On the other hand, polymer samples synthesized under different anodic potentials showed small differences, consistent with a higher degree of crosslinking at higher anodic potentials. The results obtained indicate that Py-GC/MS may be used for identification among different oxidation states in aryl amine polymers.