A comparative study of the electrodeposition of polyaniline from a protic ionic liquid, an aprotic ionic liquid and neutral aqueous solution using anilinium nitrate

A novel approach has been developed for the electrochemical deposition of polyaniline in room temperature ionic liquids. Conventionally, the deposition has required a highly proton rich electrolyte to achieve polymerisation of aniline to polyaniline. Here we report on an alternative approach where we pre-protonated the aniline to form anilinium nitrate, which could then be dissolved in electrolyte media for deposition. Three electrolyte media consisting of a protic ionic liquid, a neutral aqueous solution, and an aprotic ionic liquid were trialled. Thick yet porous deposition was achieved in the protic ionic liquid, ethylammonium nitrate, while reasonable deposition was achieved using neutral aqueous media. The use of the aprotic ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (C(4)mpyrTFSI), only led to deposition of thin films.