Electropolymerization is a synthesis of polymer film on the surface of the metal using electrochemical process. This method is applied to prevent corrosion of the metal. In this research, the synthesis of polyaniline (PANI) on stainless steel using potentiostatic method (constant potential) was investigated. The studied parameters were applied potential, time synthesis, concentration of aniline monomer and type of supporting electrolyte. Cyclic voltammetry method was used to find out the range of applied potential for PANI synthesis. The result was shown that PANI film was occurred at potential between 0.8 and 1.2 V/SCE. The increase of applied potential and aniline monomer concentration was rapidly increased PANI film growth rate. The results of morphology and composition of the PANI film were revealed by Scanning Electron Microscopy (SEM) and Fourier transform infrared (FTIR), respectively, The film was homogeneous and same functional groups as synthesized PANI in other researches. The PANI film obtained from the synthesis in electrolytes solutions: sulfuric acid, oxalic acid and sodium dodecyl sulfate, could be increased the corrosion resistance of stainless steel in 0.5 M sulfuric acid solution. The optimum condition of PANI film synthesis that provided the best corrosion protection was found at the applied potential of 0.95 V/SCE in oxalic acid containing 0.1 M aniline monomer for 20 minutes. From the electrical properties test, the PANI films prepared in sulfuric acid and oxalic acid had the contact resistances 32 and 28.4 mΩ.cm², respectively. Particularly, the sodium dodecyl sulfate had the most contact resistance of 53.7 mΩ.cm².
