Control of polyaniline electroactivity by ion size exclusion

By using an electrolytic salt solution of two anionic species differing by their ionic radius or their molecular size, it is possible to accurately control the concentration of anionic doping agent without modification of the electrolyte conductivity. The conducting polymer film is electrosynthesized on the electrode in a solution containing small ions. Once de-doped, the film keeps the memory of the size of the doping anion and can be only re-doped by comparable or smaller anions. After the synthesis, the film is transferred to another electrolyte containing heteropolyanions ensuring the conductivity and a variable concentration of small ions acting as dopants. Measurement of the electroactivity of the polyaniline film is made by linear sweep voltammetry in classical electrochemical conditions.