Benzotriazole loading in confined ZIF-8@mSiO2 nanospaces for waterborne anticorrosion coatings

Abstract

Zinc (Zn) plating is widely used for steel protection but suffers from limited long-term anticorrosion performance, and it often relies on toxic corrosion inhibitors that are increasingly restricted by environmental regulations. We report a sustainable waterborne polyurethane (WPU) coating embedded with benzotriazole (BTA)-loaded zeolitic imidazolate framework-8 (ZIF-8) nanoparticles coated with mesoporous silica (BTA-ZIF-8@mSiO₂). BTA was introduced via linker exchange, achieving strong Zn-BTA coordination, while the silica shell enhanced nanoparticle dispersion, film uniformity, and BTA loading (5.6% → 11%). This core–shell system delivers dual protection: rapid barrier action from a compact silica-modified film and sustained corrosion inhibition from controlled BTA release. Electrochemical impedance spectroscopy (EIS) showed an impedance |Z|_0.01Hz of 2.43 × 10⁵ Ω cm² and a phase angle of 70° after 21 days, indicating a sustained barrier performance over the immersion period. This strategy demonstrates the potential of MOF-silica architectures to enable environmentally friendly, high-performance waterborne coatings for durable steel corrosion control.