Doped polyaniline in Brønsted acid ionic liquid 1-butyl-3-methylimidazolium bis[trifluoromethyl(sulfonyl)]imide/bis[trifluoromethyl(sulfonyl)]imide



We report the preparation and characterization of doped polyaniline (PANI) in an ionic liquid 1-butyl-3-methylimidazolium bis[trifluoromethyl(sulfonyl)]imide (BMImTFSI) medium. Aniline monomer was chemically polymerized via oxidation with KMnO4 in an ionic liquid BMImTFSI solution containing a monoprotic Brønsted acid bis[trifluoromethyl(sulfonyl)]imide (HTFSI). HTFSI is the source of proton that doped PANI. The identity of PANI as the reaction product was confirmed with both ultraviolet–visible and Fourier transform infrared spectra. Unlike syntheses in aqueous media, the doped PANI did not readily precipitate from the ionic liquid; a transparent and stable green solution-like liquid dispersion was obtained (dispersion is used to refer the product hereafter). PANI precipitated when dedoped with organic bases such as triethylamine. The PANI precipitate can be redoped by HCl and the so-doped PANI has conductivity of about 2.0 × 10−2 S/cm. The liquid dispersion of doped PANI in the ionic liquid can be diluted by many organic solvents or other ionic liquids to diluted “solutions.” © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013