PYROLYSIS OF BF₄⁻ DOPED POLYPYRROLE BY DIRECT INSERTION PROBE PYROLYSIS MASS SPECTROMETRY

Abstract

A systematic structural and thermal characterization of conducting polypyrrole doped with BF₄ ⁻ was performed using a direct insertion probe pyrolysis mass spectrometry technique. The effect of dopant concentration on the structure and stability was investigated not only by analyzing samples with different doping levels, but also analyzing the dedoped polypyrrole sample. To get a better understanding, the changes in structure and stability upon overoxidation and thermal aging were also studied. During pyrolysis, mainly three thermal decomposition stages were observed. The first stage below 100°C was associated with evolution of adsorbed water, the solvent acetonitrile, tetrabutylammonium ion, and unreacted pyrrole. The dopant peaks such as BF₃, BF₂, and BF were recorded at moderate temperatures around 250°C, whereas, polypyrrole peaks showed up in the last stage above which is 300°C. It has been observed that at high BF₄ ⁻ concentrations aromatic structure was enhanced contrary to what was observed for p-toluene sulfonic acid doped polypyrrole in our previous studies.

Keywords:

• Polypyrrole
• BF₄ ⁻ as dopant
• Thermal degradation
• Mass spectrometry

ACKNOWLEDGMENT

This work is partially supported by TUBITAK Research Fund TBAG-1691.