pH-responsive intelligent anticorrosion protection: catechol-driven organic–inorganic hybridization with TiO2 and encapsulation by ZIF-90

A challenge in metal protection is developing anti-corrosion materials that possess both high adsorption capacity and intelligent responsiveness. To overcome the limitations of traditional corrosion inhibitors, a novel pH-responsive corrosion inhibitor (PDT@ZIF-90) was developed through a multi-step strategy. Specifically, the catechol-modified polymer–TiO2 hybrid (PDT) was synthesized through Schiff base reactions, which demonstrated dense adsorption on Q235 carbon steel through Fe–N/O coordination. Subsequent ZIF-90-mediated in situ encapsulation enabled precise payload integration of the PDT corrosion inhibitor. UV-vis characterization confirmed that the PDT@ZIF-90 composite system enables pH-triggered intelligent release of the active corrosion inhibitor component under acidic conditions (pH < 6). Electrochemical tests revealed a 95.2% inhibition efficiency for 200 ppm PDT@ZIF-90 in 3.5 wt% NaCl. This dual-functional strategy offers a scalable paradigm for self-adaptive anticorrosion materials suitable for Q235 carbon steel in marine and energy infrastructure applications.