A facile and template-free method for preparation of polythiophene microspheres and their dispersion for waterborne corrosion protection coatings

A facile, template-free method to prepare polythiophene microspheres with uniform size and well spherical shape is successfully performed, using anhydrous FeCl2 as catalyst and H2O2 as oxidant by a one-pot chemical oxidation polymerization. The structure and morphology of polythiophene nanoparticles is characterized by IR, SEM and TEM. Polythiophene nanostructures exhibit good morphology of microspheres with a very narrow particle size distribution. By fine tuning the reaction conditions, different sizes and nanostructured polythiophene can be obtained. The corrosion protection property of polythiophene microspheres-containing coatings on mild steel is investigated by electrochemical impedance spectroscopy (EIS) technique in 3.5 wt% NaCl aqueous solution. The results indicated that the waterborne polythiophene microspheres-containing coatings (polythiophene content, 0.6 wt%) could offer high protection because the impedance values remained at higher than 1 × 106 Ω cm2 after 360 h. All the results are compared with these of the pure waterborne epoxy coatings on mild steel.