INVITED: A Novel Encapsulation Design for Controlled Release Corrosion Inhibitors in Steel Reinforced Concrete

Smart technologies are an emerging trend in the field of corrosion science, particularly for the use of corrosion inhibitor release. Herein, the development of a novel smart microcapsule, containing sodium nitrite, with pH controlled release was synthesized by double emulsion method. The microcapsules were characterized for morphology by SEM, atomic composition by EDX analysis, and molecular structure by FT-IR. The encapsulation efficiency was measured by inductively coupled plasma optical emission spectroscopy to be 83%. The release of the corrosion inhibitors from the microcapsules was measured in different pH environments: simulated pore solution (12.6), carbonate buffer solution (9.1), and deionized water (6.8). It was found that the corrosion inhibitor release was greater in higher pH environments. The corrosion inhibitor efficiency of the microcapsules was evaluated with cyclic potentiodynamic polarization and electrochemical impedance spectroscopy. The microcapsules showed favorable performance at higher pH over extended periods of time, thus enhancing the corrosion protection of carbon steel rebar. Therefore, the smart microcapsules have proven to be a promising method for delivering corrosion inhibitors in reinforced concrete.