Sol-gel coating prepared using pH-responsive hollow porous organosilica nanocontainers encapsulating 2-mercaptobenzothiazole for enhanced corrosion resistance of aluminum alloy

The design of hollow porous organosilica nanocontainers (HPON) loaded with corrosion inhibitors offers innovative strategies to enhance the anticorrosive capabilities of sol-gel-derived anticorrosion coatings. In this study, intelligent pH-responsive nanocontainers, termed MBT@HPON, were fabricated using a selective silica etching method, followed by the encapsulation of 2-mercaptobenzothiazole (MBT) through π-π stacking interactions with the organosilica framework. The release kinetics of MBT from the nanocontainers demonstrated that acidic environments reduced the π-π stacking interaction, thereby imparting an acid-responsive release characteristic to the nanocontainers. The total release of MBT reached 69.6% within 24 h at pH = 3, compared to only 14.6% at pH = 7. These nanocontainers were embedded into a silica nanoparticle/methyltrimethoxysilane composite sol-gel coating, creating an intelligent coating system with active and enhanced corrosion protection on 1060 aluminum alloy. Electrochemical impedance spectroscopy analysis indicated that a 0.5 wt% doping content of MBT@HPON exhibited significantly improved electrochemical impedance for the sol-gel coating, with |Z | _f=0.01Hz exceeding 4 × 10⁷ Ω·cm² after 28 d of 3.5 wt% NaCl solution immersion, significantly higher than the pure composite coating. This superior anticorrosive performance can be attributed to the outstanding compatibility between the organosilica shell and the MTMS/silica-based sol-gel coating, along with the active corrosion inhibition from the release of MBT. This work offers valuable insights into the simple construction of sol-gel coatings with enhanced corrosion resistance based on hollow porous organosilica nanocontainers.

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