Innovative silver-based capping system for mesoporous silica nanocarriers able to exploit a two-fold anticorrosive mechanism in composite polymer coatings: tailoring benzotriazole release and capturing chloride ions

In this work, engineered stimuli-responsive mesoporous silica nanoparticles (MSN) were developed and exploited in polymer coatings as multifunctional carriers of a typical corrosion inhibitor, benzotriazole (BTA). In detail, a new capping system based on a BTA/silver coordination complex, able to dissolve in acid and alkaline conditions and to simultaneously tailor the BTA release and the capture of chloride ions, was properly designed and realized. Acrylic coatings embedding the engineered MSN were deposited onto iron rebar samples and tested for their protective capability in acid and alkaline environments. Results highlighted the high potential of the proposed system for the protection of metals, due to the synergistic effect of the mesoporous structure and the capping system, which guaranteed both the sequestration of Cl- ions and the on-demand release of the effective amount of anticorrosive agent able to ensure the enhanced protection of the substrate.