Corrosion protective properties of poly (4-(2-Thienyl) benzenamine) coating doped by dodecyl benzene sulphonate

• Poly (4-(2-theinyl)benzenamine (PTBA) was electrochemically coated on steel electrode.
• PTBA thin films with compact morphology are tightly adhered to the surface of the electrode.
• Corrosion inhibiting properties of PTBA is significantly higher than that of PANI.
• Doping of the PTBA by hydrophobic large anions enhances anticorrosion properties greatly.

Poly (4-(2-Thienyl) benzenamine) (PTBA) and corresponding homopolymers doped with sodium dodecyl benzene sulfonate (SDBS) and dedoped polymer coatings on steel surface have been synthesized by galvanostatic method. The anticorrosion performances of PTBA and its homopolymers coatings were investigated in 3.5 wt% NaCl solution by the potentiodynamic polarization technique, Tafel test and electrochemical impedance spectroscopy (EIS). The PTBA was found to exhibit enhanced corrosion protection effect on stainless steel electrode in comparison with poly aniline (PANI) and poly thiophene (PTh) homopolymers. The corrosion rate of SDBS doped PTBA-coated steel was found ∼193 times lower than that of bare steel. Corrosion potential for uncoated steel increases (−0.506 mV versus Ag/AgCl/Cl−(sat.)) to +40 mV for SDBS doped PTBA-coated steel electrodes. The results of this study clearly indicate that the PTBA doped by SDBS has an outstanding potential to protect the steel against corrosion in a chloride ion environment.