Excellent impermeability, electronic insulation, thermal stability, and high surface area of hexagonal boron nitride nanosheets (h-BNNS) promise immense potential for corrosion inhibition when coated on the metal substrate. However, the interfacial incompatibility of h-BNNS with polymeric coating matrix has been a major challenge to utilize h-BNNS for metal protection against corrosive environments. In the present work, surface-functionalities-enriched h-BNNS prepared by alkali hydroxides molten salt-induced exfoliation of h-BN powder is used for in-situ growth of polyaniline-emeraldine salt (PANI-ES) by oxidative polymerization of aniline to prepare the h-BNNS-PANI-ES nanocomposites. The excellent compatibility of nitrogen functionalities of h-BNNS-PANI-ES nanocomposites with highly polar epoxy matrix strengthened the coating by enhancement of elastic modulus and hardness. The thoroughly dispersed h-BNNS-PANI-ES nanocomposites into epoxy coating notably enhanced the corrosion inhibition properties in an accelerated corrosive environment (3.5 % saline water). The electrochemical measurements showed eleven-fold rise in total impedance by h-BNNS-PANI-ES nanocomposites compared to PANI-ES-based epoxy coating, highlighting the role of h-BNNS as a structural barrier to protect the underlying mild steel substrate against corrosion. Moreover, mild steel coated with h-BNNS-PANI-ES nanocomposites remained intact even after ten days of exposure to salty fog, demonstrating the potential of such coatings for industrial applications.

Polyaniline-wrapped h-boron nitride nanosheets as anticorrosive filler in epoxy coatings for substantially enhanced protection of mild steel