Thermal analysis of chemically synthesized polyaniline and effects of thermal aging on conductivity

TLDR: In this paper, the HCl-doped polyaniline showed three major weight losses at around 100, 200, and 500°C which are assigned to removal of H2O and HCl, and decomposition of the polymer, respectively.

Abstract: Thermal characteristics of chemically synthesized polyaniline with various dopants have been studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy, gel-permeation chromatography (GPC), and chemical titration. The HCl-doped polyaniline shows three major weight losses at around 100, 200, and 500°C which are assigned to removal of H2O and HCl, and decomposition of the polymer, respectively. Thermal aging of the HCl-doped polyaniline performed at 100, 150, and 200°C for various periods of time results in a decrease in conductivity. After the thermal treatments, the polymer can be re-doped with HCl to partially recover the conductivity. However, both the conductivity and the doping level cannot be restored to the level of the original materials owing probably to changes in morphology, crosslinking, or other chemical reactions.