Thiophene (Th), 3-hexylthiophene (3HT) and their nanocomposites with TiO 2 were electropolymerized on Al1050 electrode by chronoamperometic technique. Different concentrations of Th and 3HT homopolymers and their nanocomposites with TiO 2 (2% in total content) were characterized by attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), energy dispersion Xray analysis (EDX) and electrochemical impedance spectroscopy (EIS). The capacitive behaviours of modified electrodes were calculated from Nyquist, Bode-magnitude, Bodephase and Admittance plots. The optimum conditions of capacitive behaviours of homopolymers (PTh and P3HT) and their nanocomposite films of PTh/TiO 2 and P(3HT/TiO 2 ) were electrocoated on an Al1050 electrode by chronoamperometric technique. The anti-corrosion tests for homopolymers and nanocomposite films were examined in 3.5% NaCl solution. The EIS and Tafel extrapolation results were comparatively studied. In all cases, polymer and nanocomposite films have protective behavior of Al1050 against corrosion. P(3HTh)/TiO 2 nanocomposite films gave the highest protection effeciency (PE) = 98% because the amount of defects was much lower than that for the P(3HTh), PTh and PTh/TiO 2 films.

In this study, 3-octylthiophene (3OT) and its nanocomposites with TiO 2 (3OT/TiO 2 ) were electrochemically synthesized in different initial monomer concentrations (50, 75, 100, and 150 mM) in 0.1 M tetraethylammonium tetrafluoroborate (TEABF 4 )/acetonitrile (CH 3 CN) on a glassy carbon electrode (GCE). The best modified electrodes, which were taken from the optimum conditions of redox behaviors, were also electropolymerized in 0.5 M oxalic acid/acetonitrile (CH 3 CN) solution on Al1050 electrode. The modified Al1050 electrodes were characterized by optical microscope, FTIR-ATR, SEM-EDX, and EIS. The optimum conditions of the electrocoated P(3OT)/Al1050 and P(3OT)/TiO 2 nanocomposites on Al1050 electrode were investigated for corrosion performances against 3.5% NaCl solution. The corrosion tests were performed by EIS and Tafel extrapolation plots together with the equivalent circuit model of R s (Q c (R c (Q p R ct ))). P(3OT)/TiO 2 nanocomposite films showed higher protection efficiency (PE ¼ 89%) than P(3OT) films (PE ¼ 81%). The P(3OT)/TiO 2 nanocomposite films coated on Al1050 electrodes may be used in industrial applications of corrosion protection against salt water.