pH-responsive ZIF-8 derived LDH nanocontainers with phosphate intercalation for dual active-passive corrosion protection in coatings

The integration of inhibitor-encapsulated nanocontainers within organic coatings offers a viable approach for achieving sustained corrosion mitigation and extended protective functionality. In this study, a ZIF-8@LDH-P (ZLP) nanocontainer was developed, consisting of Ni-Co layered double hydroxide (LDH) derived from zeolitic imidazolate framework-8 (ZIF-8) precursors and incorporating trisodium phosphate (TSP) as a corrosion inhibitor. The release of phosphate ions from ZLP exhibited pH-responsive behavior, enabling triggered inhibitor release under corrosive conditions. When uniformly dispersed in the polyvinyl butyral (PVB) resin matrix and coated on Q235 carbon steel, the PVB/ZLP composite coating demonstrated an enhancement of two orders of magnitude in low-frequency impedance modulus (|Z| 0.01 Hz ) relative to pure PVB. Furthermore, the PVB/ZLP coating exhibited long-term protective capabilities, ascribed to the cooperative effect of regulated phosphate ions release for active corrosion inhibition, chloride ion entrapment by LDH interlayers, and the prolonged diffusion pathways for corrosive agents enabled by the lamellar structure of LDH. This study offers novel design strategies for ZIF-derived LDH nanocontainer-based anti-corrosion coatings with inhibitor loading.