Efficient self-healing coatings embedded with polydopamine modified BTA@DMSNs for corrosion protection

Dendritic mesoporous silica nanoparticles (DMSNs) were successfully prepared with a specific surface area of 608.8 m 2 /g and an average pore size of 24.2 nm, providing a strong support for the successful loading of benzotriazole (BTA). BTA@DMSNs were prepared using the vacuum impregnation method. A pH-responsive polydopamine (PDA) outer layer was self-polymerized on the surface to obtain BTA@DMSNs/PDA microcapsules. The pH-responsive BTA@DMSNs/PDA microcapsules were prepared with the high BTA content of 20.1 wt%. Mean diameter of microcapsules was 210 ± 25 nm. The release profiles under different pH conditions confirmed the pH-responsive behavior of BTA/DMSNs@PDA microcapsules. The coatings with 1 wt% BTA@DMSNs/PDA microcapsules exhibited optimal anti-corrosion and self-healing performance. The |Z| 0.01Hz of EP/1 wt%/BTA/DMSNs@PDA remained the highest among all coatings even after being immersed in 3.5 wt% NaCl solution for 50 d through the EIS measurement. It only had a slight change from 3.8 × 10 10  Ω·cm 2 to 6.8 × 10 9  Ω·cm 2 , which was 80 times that of the EP for 50 d, indicating that the coatings had excellent long-term anti-corrosion effect and good shielding performance. Furthermore, the |Z| 0.01Hz of the artificially cross-scratched coatings that were immersed for 30 d remained at 6.9 × 10 4  Ω·cm 2 , which was one order of magnitude higher than EP (6.3 × 10 3  Ω·cm 2 ), and the surface of coatings remained intact, showing that the scratched coatings had outstanding self-healing performance.