Synergistic interfacial engineering enabled by porous self-responsive interlayers for durable, high-adhesion metal coatings

Achieving durable bonding at polymer/metal interfaces under corrosive environments remains challenging due to mismatches in thermal expansion and interfacial polarity, which facilitate electrolyte infiltration and premature coating failure. A cooperative interfacial engineering strategy is presented to enhance both adhesion and corrosion resistance by constructing an ordered porous polydopamine (PDA) film using a P123/TMB soft-template system. The PDA interlayer increases surface energy through abundant functional groups, while its porous architecture provides structural interlocking with the polymer coating. Incorporation of benzotriazole (BTA) into PDA nanochannels enables pH-responsive release, forming protective complexes at damaged sites for active corrosion inhibition. Introduction of the PDA@BTA interlayer increases epoxy coating (EP) adhesion strength by 42.36%, and after 75 days of seawater immersion, |Z|₀.₀₁ Hz and charge-transfer resistance (R ct ) increase by 2503.4% and 591.4%, respectively, indicating long-term stability. First-principles calculations reveal that interfacial reinforcement arises from coordination between PDA and the metal and multiple weak interactions with the polymer, forming a robust interfacial network. This integrated design provides a pathway toward durable multifunctional corrosion-resistant systems.