Characterization and corrosion of polypyrrole/sodium dodecylbenzene sulfonate electropolymerised on aluminum alloy 1100

In this study films of polypyrrole/sodium dodecylbenzene sulfonate (PPy/SDBS) were electropolymerised on the surface of platinum to determine their chemical and physical characteristics and on AA 1100 alloy to evaluate their performance in terms of corrosion protection of the alloy in chloride solutions. The characterization of the films was performed by scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and conductivity measurements. The XRD and FT-IR analysis of the PPy/SDBS films showed that the SDBS confers a higher degree of order to the PPy deposits, this effect being evident from the relatively high value obtained for the electrical conductivity of the films. Moreover, the films presented environmental stability with conductivity values remaining stable even after 60 days of air exposure. The thermal analysis showed that the PPy/SDBS film is amorphous and degrades without melting. The corrosion protection of the films produced on the AA 1100 surface was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in 0.05 mol L−1 NaCl and 0.05 mol L−1 HCl solutions. The potentiodynamic polarization curves of the PPy/SDBS coatings produced on the AA 1100 surface evidenced a shift of the corrosion potential to more positive values and a decrease of the corrosion current density, indicating an improve on the corrosion resistance.