Designing of Layered Double Hydroxides (LDHs)–Conductive Polymer Composites for Epoxy-Based Anticorrosive Coatings

The development of epoxy-polyamide-based anticorrosive coating is done with the incorporation of LDH–conductive polymer composites. The zinc–aluminum LDH and magnesium–aluminum LDH were developed by precipitation method. The synthesized LDH is surface treated with amino silane, and it helps for smooth grafting of conductive polymers on the surface of LDH. The polyaniline (PANI), polyorthoanisidine (POA), and PANI-POA copolymer are studied as grafting material on the Zn–Al and Mg–Al LDH, respectively, by chemical oxidation method for the polymerization. The synthesized LDH–conductive polymer composites are characterized by FTIR and XRD analysis for the confirmation of successful synthesis and further incorporated into an epoxy-polyamide matrix at 4% (w/w) concentration. The coating is applied on the mild steel surface. The addition of LDH–conductive polymer composite increases the coating's pencil hardness and scratch resistance. The corrosion resistance properties of the coating are evaluated by salt spray analysis; by the synergistic effect of LDH and conductive polymers, the coating based on such composites shows better corrosion resistance than plain epoxy coatings. Zn–Al-POA composites show the best mechanical properties and corrosion resistance performance among all studied formulations.