pH-Responsive zeolitic imidazole framework nanoparticles with high active inhibitor content for self-healing anticorrosion coatings

Zeolitic imidazole framework (ZIF) is an emerging class of functional materials with promising nanostructures and applications in biomedicine and materials science. Herein we present a dynamic protective coating system with self-healing anticorrosion function, based on pH-responsive ZIF nanoparticles. Due to the advantage of high content of corrosion inhibitor in the ZIF-7 nanoparticles and its nature of pH-sensitivity, the ZIF-7 nanoparticles could quickly respond to the surrounding acid environment and release the linker as healing agent, led to a new barrier on scratched metal surfaces. The embedding and homogeneous distribution of the ZIF-7 nanoparticles in polymer coating system improved the corrosion resistance of carbon steel in 0.1 M hydrochloric acid solution in comparison to the control samples, as determined by electrochemical impedance spectroscopy (EIS). The self-healing anticorrosion property of dynamic polymer system was characterized during a simulated corrosion process by scanning electrochemical microscopy (SECM). The concentration of the embedded ZIF-7 nanoparticles was varied (0.5 - 7 wt %) to ascertain the optimum conditions for anticorrosion performance. The important effect of particle size and shape of ZIF-7 nanoparticles is discussed as well. The ZIF-7 based on dynamic protective polymer systems can interact with and adapt to the surrounding acid environment, leading to a new healed barrier on metal surfaces with anticorrosion functions.