Polyelectrolyte coatings on hematite nanoparticles impregnated with corrosion inhibitor benzotriazole

Hematite nanoparticles (α-Fe2O3) were encapsulated with polymers for application as nanocontainers that can release entrapped corrosion inhibitor in response to pH changes in the environmental medium. Positively charged rod-like particles were coated by sequential adsorption of poly(acrylic acid) (PAA) and poly(diallyldimethylammonium chloride) (PDADMAC) using layer-by-layer assembly technique. Hydrodynamic thickness and electrical properties of the coating were determined by electric light scattering method before and after loading with corrosion inhibitor benzotriazole (BTA). The electro-optical determinations were complemented measuring the electrophoretic mobility of the polymer coated particles. Higher loading of positively charged BTA in the coatings was achieved when they were terminated with negatively charged PAA layer. Inclusion of like charged PDADMAC into a pure PAA coating was found to decrease the content of entrapped BTA, but the loading capacity of thus prepared nanocontainers remains high enough for corrosion protection of metallic substrates.