Influence of microwave irradiation on various properties of nanopolythiophene and their anticorrosive nanocomposite coatings

Abstract

Nano conducting polymer (CP) dispersed polymer hydrophobic coatings are considered to be a new generation coating system. They have promising applications in the area of anticorrosive coatings and have proved to be an effective alternative to the toxic phosphate–chromate based coatings. In view of this, for the first time, we report here the effect of microwave (MW) irradiation on various properties of polythiophene (PTh) and compare with conventionally polymerised nano PTh (cPTh). The effect of MW irradiation on the morphology, size, solubility and electrical properties are investigated with the help of TEM, SEM, CV and four probe conductivity measurements. The synthesis has been carried out in aqueous medium, as it is green, renewable, environmentally friendly and free from harmful VOCs. The nano PTh dispersed epoxy-polyamide (PA) nanocomposite coatings are developed on carbon steel (CS). The mPTh–epoxy-PA shows superior flexibility, gloss, adhesion, impact and scratch resistance properties than those of the cPTh–epoxy-PA nanocomposite coatings. The salt spray test and potentiodynamic polarization (PDP) studies on these coatings reveal that the mPTh–epoxy-PA nanocomposite coatings show superior anticorrosive properties (E_corr/I_corr: −0.30301 V/3.1587 × 10⁻⁹ A cm⁻²) than cPTh–epoxy-PA (−0.32138 V/1.1003 × 10⁻⁸ A cm⁻²) and epoxy-PA (−0.45505 V/9.3862 × 10⁻⁷ A cm⁻²) coatings. The morphology of corroded and uncorroded coatings are analysed by SEM/EDAX. The promising physico-mechanical properties and corrosion protection performance of mPTh–epoxy-PA nanocomposite coatings highlighted the potential of MW techniques for the synthesis of CPs.