A novel smart pH-responsive nanocomposite based on cerium-polyphenol -amine self-assembly for anticorrosion waterborne epoxy coatings

To overcome the limited protective performance of waterborne epoxy (WEP) coatings, a novel scalable cerium-polyphenol-amine ternary system (Ce-TA-PEI, CTP) was synthesized via a simple dynamic supramolecular self-assembly strategy. The material effectively anchored corrosion-inhibiting cerium ions within its network through cerium-phenolic coordination, achieving an exceptionally high cerium loading capacity of 20.3 wt%. The polyphenol–amine crosslinked network of the CTP nanocontainer can form chemical bonds with the epoxy matrix, ensuring good interfacial compatibility and significantly reducing the intrinsic defects of the coating. Consequently, the dry and wet adhesion strengths of the coating increased to 3.13 MPa and 2.99 MPa, respectively. After 60 days of immersion in 3.5 wt% NaCl solution, the | Z | 0.01Hz value of CTP2/WEP remained as high as 1.21 × 10 9  Ω·cm 2 , more than an order of magnitude greater than that of pure WEP (1.05 × 10 8  Ω·cm 2 ). In addition, UV–Vis analysis confirmed that CTP is pH-responsive and can sustain continuous cerium release for up to 144 h. This behavior arises from changes in coordination strength between cerium ions and phenolic hydroxyl groups, together with variations in electrostatic interactions within the CTP framework under different pH conditions, which promote rapid cerium release in acidic environments. When incorporated into WEP coatings, this “smart” nanocontainer responded dynamically to localized acidic corrosion at coating defects. It not only enhanced the physical barrier properties of the coating but also imparted active self-healing functionality. This work therefore provides a new strategy for advancing environmentally friendly WEP coatings toward broad engineering applications.