Effect of self-doping groups in polyaniline chains on the electrochemical properties of full polyanilines self-assembled films

Full conjugated self-assembled multilayer films from the two polymers, partially doped polyaniline (PANI) as polycation and poly (o-aminobenzoic acid) (PCAN) or poly (aniline-2-sulfonic acid) (PSAN) as polyanion, were fabricated with the layer-by-layer (LBL) technique. The experiments revealed that the UV-Vis absorbance of LBL films increased linearly with the increase of dipping cycle number, which indicated that the amount of polyelectrolyte deposition on the surface of the films in every cycle was uniform. Because sulfonic groups in PSAN had higher electro-negativity than carboxylic groups in PCAN, the molecular chain s stretch and distance among chains were greater than that of PCAN. So the deposition amount of PANI-PSAN in every dipping cycle was less than that of PANI-PCAN in the same condition, which the absorbance of PANI-PSAN film was smaller than that of PANI-PCAN film in the same bilayer number. In conventional three-electrode CV test, the electrochemical properties of the two LBL films mainly depended on pure PANI because the conductibilities of both PCAN and PSAN were weaker than PANI. Compared with PANI-PSAN films, the electrochemical properties of PANI-PCAN films were better due to the effect of deposition.