In situ-polymerized and nano-hybridized Ti3C2-MXene with PDA and Zn-MOF carrying phosphate/glutamate molecules; toward the development of pH-stimuli smart anti-corrosion coating

Abstract

A smart anti-corrosion epoxy coating (EPC) was designed on the basis of polydopamine (PDA), and zeolitic imidazolate framework8 (ZIF8) tailored MXene (Ti3C2) sheets, which were loaded with two different corrosion inhibitors, namely phosphate and glutamate ions. The utilization of these inhibitor-loaded hybrid carriers in EPC yielded self-healing properties and prolonged resistance against corrosion. First, characterization tests including FT-IR, Raman, XRD, XPS, BET, TGA, SEM, and HRTEM were performed to confirm the synthesis of the constructed containers. Then, the inhibition efficiency and mechanism of the container were investigated via ICP and electrochemical (EIS and polarization) analyses. The synthesized PM-ZP and PM-ZG containers loaded with phosphate and glutamate inhibitors were proven to have a promising efficiency in reducing the corrosion of the metal, as the inhibition efficiency in the polarization test was demonstrated to be 42.17 and 60.31 %, respectively. The impedance values in the EIS test regarding solution media showed a considerable increment in PM-ZP (6511.3 Ω.cm2@3h) and PM-ZG (5438.3 Ω.cm2@5h) compared to the unprotected steel (2081.0 Ω.cm2@24 h). The self-healing potential of the nanocomposite containing PM-ZP and PM-ZG samples was manifested through the EIS test, FE-SEM as well as EDX maps of coatings with artificially produced scratches. The intact coatings’ long-term barrier characteristics were also investigated with an EIS test and impedance values > 40 Ω.cm2 and log|Z|10mHz > 10.5 justified the high performance of epoxy composites containing PM-ZP and PM-ZG synthesized carrier after 90 days of immersion in aggressive media. Pull-off, salt spray, and cathodic disbonding tests revealed that coatings containing PM-ZP and PM-ZG carriers outperformed epoxy coatings without corrosion inhibitors.