Electrodeposition of polythiophene, polypyrrole and polyaniline by the cyclic potential sweep method

The cyclic potential sweep (CPS) technique was applied to deposition of electroactive polymers and tested on polythiophene (PT) and polypyrrole (PP), both in acetonitrile, and polyaniline (PANI) in sulfuric acid. The relationship between deposition charge Qi and the CPS parameters (number of cycles N, scan rate v and switching potential E?) has the simple form Qi ~ (N/v)n exp(aE?), with n =1 for PT and PP and n = 2 for PANI. The dependence on monomer concentration is analogously square for PANI and linear for PT; for PP, the dependence is linear only in the presence of water, which acts as a scavenger of electrogenerated protons. The growth mechanism is reflected by n (over a substrate of constant area for n = 1 and expanding linearly in time for n = 2). The CPS relationships are explained satisfactorily by chronoamperometric results.