Dual-functional ZIF-8 as a curing promoter and nanocontainer for responsive inhibitor release in enhanced protection of bronze artifacts

A smart anti-corrosion coating featuring ZIF-8 nanocontainers was developed for bronze artifact conservation. • ZIF-8 serves a dual function: accelerating epoxy resin curing and enabling pH-responsive release of benzotriazole. • The optimized coating (2.0 wt% filler) exhibits superior barrier properties and enhanced corrosion resistance. • Active self-healing is triggered by damage, where released inhibitor forms a Cu-N coordination film to inhibit corrosion. The effective conservation of bronze artifacts is hindered by the shortcomings of conventional protective coatings. These materials typically cannot self-repairing after damage, allowing corrosion to progress, and often require high curing temperatures that may damage the bronze artifacts. To address these issues, this study develops a multifunctional epoxy coating based on zeolitic imidazolate framework-8 (ZIF-8). ZIF-8 plays a dual role in this system: as a curing accelerator, its tertiary amine groups catalyze the epoxy curing reaction, significantly reducing the activation energy from 130.74 kJ·mol −1 to 59.06 kJ·mol −1 ; and as a pH-responsive nanocontainer, it encapsulates the corrosion inhibitor benzotriazole (BTA) and releases BTA intelligently upon coating damage and corrosion-induced acidic microenvironment-triggered, enabling active self-repairing. Experimental results show that with a BTA loading of 8 mol% and a filler content of 2.0 wt%, the coating exhibits optimal long-term anti-corrosion performance during a 50-day immersion test. After scratching, the low-frequency impedance modulus of the coating recovers rapidly within 2 h and peaks between 8 and 12 h, confirming its fast self-repairing capability. Raman spectroscopy and theoretical calculations reveal that the repairing mechanism stems from the formation of a stable protective film via Cu N coordination between released BTA and the bronze substrate. This work provides an intelligent protection strategy for bronze artifacts, integrating 70 °C curing with active self-repairing functionality. Download: Download high-res image (128KB) Download: Download full-size image