Ionic liquid-induced formation of polyaniline nanostructures during the chemical polymerization of aniline in an acidic aqueous medium

Nanostructured polyanilines (PANIs) with a variety of morphologies were synthesized in acidic aqueous solutions with an added ionic liquid, 1-butyl-3-methylimidazolium chloride. The influence of various reaction conditions, i.e., the molar ratio of aniline to ionic liquid and initial aniline concentration, on the morphology and properties of the synthesized PANIs were investigated. The morphologies of the PANIs, as studied by scanning electron microscopy (SEM), range from nanowires to complex three-dimensional structures and were influenced particularly by the molar ratio of aniline to ionic liquid. The chemical structure and molecular-weight characteristics, as determined by Fourier-transform infrared spectroscopy (FTIR), UV–Vis spectroscopy and size-exclusion chromatography (SEC), were not affected by the reaction conditions, indicating that the aniline polymerization mechanism did not change in the presence of the ionic liquid, which acted as a soft template. The conductivities of the prepared PANI samples, as measured by impedance spectroscopy, were of the order of 10−2 S/cm.