Thermal analysis of polyaniline. Part I. Thermal degradation of HCl-doped emeraldine base.

Abstract Hydrochloric acid-doped emeraldine base has been subjected to programmed thermal degradation under high vacuum conditions. The temperature profiles of the degradation processes have been mapped using thermogravimetry (TG) in conjunction with thermal volatilization analysis (TVA). Product distributions have been ascertained using the fractionating capability of the TVA system in conjunction with ancillary techniques of analysis such as infrared (IR) and proton nuclear magnetic resonance (NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS). At low temperatures ( c . 200 °C) HCl gas is evolved. At higher temperatures the polymer is subject to complex and overlapping processes involving chain scissions, ring fusions and fragmentations, and heterocycle production. These observations are rationalized through the construction of a family of plausible reaction mechanisms which are consistent with our measured product distributions.