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

• A template-free reaction system (FeCl2/H2O2/thiophene) is adapted to prepare polythiophene microspheres.
• The microspheres show uniform size, good thermal stability, solubility and spherical shape.
• Well-dispersed polythiophene-containing waterborne epoxy coatings for Q235 steel are prepared.
• After 360 h of immersion, the impedance values remain at higher than 1 × 106 Ω cm2.
• The coatings have low corrosion current (2.297 × 10−8 A cm−2).

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.

Polythiophene microspheres with uniform size and low PDI were prepared by a facile, one-pot method. Owing to its uniform and small particle size, polythiophene microspheres can be well dispersed to be utilized in waterborne corrosion protection coatings. The results showed the polythiophene-containing waterborne coatings could offer high protection with impedance values remained at higher than 1 × 106 Ω cm2 after 360 h of immersion in 3.5 wt% NaCl aqueous solution. And the corresponding low corrosion current (2.297 × 10−8 A cm−2) showed much better protective effect than pure waterborne epoxy coatings.Figure optionsDownload as PowerPoint slide