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

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.

The authors acknowledge financial support from the Universidad de Buenos Aires (UBACYT 2004–2007 X105), the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, PIP 02287) and the Agencia Nacional de Promoción Científica y Tecnológica (grant N° 06-12467) from Argentina. L.L. is indebted to the Universidad de Buenos Aires for an R.H. Tallman fellowship which supported his stay in Spain. F.V.M. is a member of the Carrera del Investigador Científico of CONICET.

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