Zn-Al layered double hydroxides as chloride nanotraps in active protective coatings

Abstract

Zn–Al layered double hydroxides (LDHs) intercalated with nitrate anions are suggested as chloride nano-traps for organic polymeric coatings. The addition of such nanotraps to a polymer layer drasticallyreduces the permeability of corrosive chloride anions through the protective coatings. In solution,Zn(2)–Al–NO3LDHs are responsive to the concentration of chlorides and the release of nitrates is accom-panied by entrapment of chlorides, with the process governed by ion-exchange equilibrium. In particular,a coating modified with LDH–NO3was found to exhibit significantly lower permeability to chlorideswhen compared to both unmodified and LDH–Cl-containing coatings, which proves the applicability ofLDHs in delaying coating degradation and corrosion initiation.