Conducting poly(o-anisidine) nanofibre dispersed epoxy-siloxane composite coatings: synthesis, characterization and corrosion protective performance

Conducting polymers (CPs) exhibited a promising ability of corrosion inhibition and find application in the formulation of new generation smart anti-corrosive coating materials. CPs not only act as an active barrier for corrosive ions but also provide protection to the metal substrate through the redox mechanism. In view of this, the present article reports the synthesis, structural, physico-chemical, physico-mechanical characterization and corrosion protective performance of tartaric acid (TA) and functionalized protonic acid-dodecyl benzenesulphonic acid (DBSA) doped poly(o-anisidine) nanoparticles (TA-DBSA-POA) and these nanoparticles dispersed epoxy-siloxane (ES) nanocomposite coatings (TA-DBSA-POA-ES) on carbon steel (CS). The structure, size and morphology of TA-DBSA-POA nanoparticles and those of coatings were investigated by FT-IR, XRD, TEM and SEM analysis. The conductivity of TA-DBSA-POA nanoparticles (2.09 S cm(-1)), and TA-DBSA-POA-ES nanocomposites (5.02 x 10(-3) S cm(-1)) as well as their thermal stability were investigated with the help of the four-probe method and the TGA technique. The physico-mechanical properties of these coatings were evaluated using standard laboratory methods. To the best of our knowledge, the corrosion protective performance of these coatings was investigated for the first time in our laboratory, using the salt spray test (SST), potentiodynamic polarization (PDP), and electron impedance spectroscopy (EIS) techniques at varying concentrations of NaCl viz. 3.5 wt%, 5.0 wt% and 7.0 wt% NaCl. SEM-EDAX and Raman studies revealed the presence of a passive ferric oxide layer. These studies revealed that nanocomposite coatings show far superior thermal stability, physico-mechanical and corrosion protective performance than plain ES and other such CP reinforced epoxy coating systems.