Effect of acids on in situ polyaniline film formation

The chemical oxidation of aniline with ammonium persulfate (APS) to form polyaniline (PANI) films has been studied in different aqueous acid media such as sulfuric, nitric, phosphoric and acetic acids. A comparison was made between the yields of PANI film deposition during the polymerization from these media with the corresponding one obtained previously from aqueous HCl solution. The degradation of the formed PANI films at the beginning of polymerization obtained at the higher concentrations of HCl is absent when the other acids under consideration were used. The effect of acid concentration on the yield and growth rate of the PANI film was studied. The variation in the yield and growth rate of the polymer films at different acid concentrations was explained on the basis of the electrostatic repulsion and the screening effects. (C) 2004 Society of Chemical Industry.