Polydopamine-coated zeolitic imidazolate framework for enhanced anti-corrosion and self-healing capabilities of epoxy coating on magnesium alloy
Xiaomeng Yu, Yujiao Ma, Dan Xu, Jiao Li, Zhiyuan Feng, Yuejun Ouyang, Qiwen Yong, Zhihui Xie
Abstract
This study lies in the first-time incorporation of polydopamine (PDA)-modified zeolitic imidazolate framework-8 (ZIF-8) smart nanocapsules (ZIF-8@PDA) with epoxy resin , systematically improving the comprehensive performance of magnesium alloy coatings and proposing a novel anti-corrosion mechanism based on physical barrier and dual self-healing characteristics. The PDA coating formed on the ZIF-8 surface creates a uniform, dense, and relatively impermeable barrier layer, which enhances the stability of ZIF-8 within the coating matrix. Electrochemical impedance spectroscopy (EIS) tests demonstrate that while the overall electrochemical impedance of the pure epoxy coating decreases, the ZIF-8@PDA 1.0wt% /EP coating exhibits a significant increase in impedance between 10–12 h after being scratched, indicating remarkable self-healing capabilities. After 50 days of immersion in a 3.5 % NaCl solution, the low-frequency impedance value (|Z| 0.01 Hz ) of the pure epoxy coating rapidly declines to 0.15 MΩ·cm 2 , whereas the ZIF-8@PDA 1.0wt% /EP sample shows a much smaller decrease, maintaining an impedance of 50 MΩ·cm 2 , and the charge transfer resistance ( R ct ) of the ZIF-8@PDA 1.0wt% /EP coating is three orders of magnitude higher than that of pure EP coating, underscoring the exceptional corrosion inhibition performance. This study introduces a groundbreaking approach to developing smart epoxy coatings with superior corrosion resistance for magnesium alloys.