Characterization of electrochemically synthesized p-toluene sulfonic acid doped polypyrrole by direct insertion probe pyrolysis mass spectrometry

A direct insertion probe pyrolysis mass spectrometry technique was used to perform a systematic thermal characterization of conducting polypyrrole doped with p-toluene sulfonic acid. The effect of dopant concentration on thermal stability and degradation products was investigated using undoped and dedoped polypyrrole samples. The data indicate that polymerization of pyrrole in the absence of dopant produces an aromatic structure, which transforms into the quinoid form at high dopant concentrations. Reduction, namely dedoping, yielded a decrease in the intensity of PTS based peaks and transformation from quinoid form to aromatic form. Intense toluene, SO2, and H2S peaks recorded at high temperatures indicated the decomposition of the dopant. This trend, decomposition at high temperatures instead of evaporation at low or moderate temperatures was associated with a strong (probably chemical) interaction between the dopant and the host polymer. (C) 2002 Elsevier Science B.V. All rights reserved.