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

Zn–Al layered double hydroxides (LDHs) intercalated with nitrate anions are suggested as chloride nanotraps for organic polymeric coatings. The addition of such nanotraps to a polymer layer drastically reduces the permeability of corrosive chloride anions through the protective coatings. In solution, Zn(2)–Al–NO3 LDHs are responsive to the concentration of chlorides and the release of nitrates is accompanied by entrapment of chlorides, with the process governed by ion-exchange equilibrium. In particular, a coating modified with LDH–NO3 was found to exhibit significantly lower permeability to chlorides when compared to both unmodified and LDH–Cl-containing coatings, which proves the applicability of LDHs in delaying coating degradation and corrosion initiation.