Oxidative stability of polyaniline

Standard globular and nanotubular polyaniline were exposed to strong oxidants, such as hydrogen peroxide or ammonium peroxydisulfate, in acidic, neutral, and alkaline aqueous media for 10 or 60 days. Even in the mixture of 30% hydrogen peroxide and concentrated sulfuric acid, polyaniline was not completely destroyed and left >30 wt.% residue. In 1 m ammonium peroxydisulfate dissolved in various media, only marginal changes in mass of polyaniline were observed, except for concentrated sulfuric acid where the residue was ≈10 wt.%. A partial dissolution of globular polyaniline in acid was responsible for this result. The changes in the molecular structure have been assessed by UV-visible, FTIR, and Raman spectroscopies. The oxidation stability of nanotubular polyaniline was better compared with the common globular form. After the exposure to oxidants in acidic media, the conductivity was reduced but not completely.