Enhancement of Active Anti-Corrosion Properties of Waterborne Epoxy Resin by Mussel Bionic Modified Halloysite Nanotube

Halloysite nanotube (HNT) is often used as a microcapsule loaded with corrosion inhibitors due to its cavity structure. However, the strong van der Waals forces between halloysite nanotubes can cause aggregation in organic coatings. Therefore, in this study, a new type of modified halloysite nano-filler (PDA@T-AHNT) was synthesized by a step-by-step method using the characteristics of self-polymerization of dopamine under an alkaline environment to achieve surface coating of halloysite nanotubes by polydopamine (PDA) to improve the dispersion of halloysite nanotubes in waterborne epoxy resin. UV-Vis was used to characterize the pH-responsive release properties of the modified nanofillers. Composite coatings were formed by adding PDA@T-AHNT into the water-based epoxy resin. FE-SEM was used to observe the morphology of the coatings, and EIS was used to test the electrochemical behavior of the coatings soaked in 3.5 wt% NaCl for 60 days to characterize the corrosion resistance of the coatings. The final results show that the 3 wt% PDA@T-AHNT composite coating (EPP-3) has the best corrosion resistance with a low-frequency impedance of 2.81 * 106 Ohm.cm2 after 60 days of immersion, which is much higher than the 1.45 * 106 Ohm.cm2of the pure epoxy resin coating (WEP). In conclusion, the results of this study demonstrated the application potential of PDA@T-AHNT nano-filler in corrosion protection of steel, especially in metal corrosion protection under acidic environment.