Encapsulation of dodecylamine corrosion inhibitor on silica nanoparticles

The use of nanocontainers or nanoreservoirs containing corrosion inhibitors as active corrosion protection systems is one of the issues of great interest in the corrosion protection scientific literature. The aim of this paper is to study the use of nanocontainers with dodecylamine encapsulated for active corrosion protection of carbon steel. To produce the nanocontainers the LbL deposition procedure was used where several polyelectrolytes (PEI and PSS) and inhibitor (dodecylamine) layers were alternatively deposited on SiO2 nanoparticles surface for obtaining a final structure of SiO2/PEI/PSS/dodecylamine/PSS/dodecylamine type. The tests for indirectly evaluating the amount of released inhibitor from nanocontainers was performed evaluating the corrosion resistance of carbon steel samples by electrochemical impedance (EIS) measurements in aerated 0.1 mol/L NaCl solution containing (1 wt.%) nanocontainers at different pH values (2.0, 6.2 and 9.0). The anticorrosive performance of an alkyd primer loaded with 10 wt.% of nanocontainers containing entrapped dodecylamine was tested on coated carbon steel panels with a provoked defect, by immersion of the coated samples in 0.01 mol/L NaCl, by EIS and scanning vibrating electrode technique (SVET). The results of EIS were treated and kinetics curves showed that for pH = 2 condition the release of inhibitor was more rapid and efficient in comparison to other pH conditions (9 and 6.2) where the release was slower allowing to prove the nanocontainers permeability properties for an external stimulus of pH change. The release of dodecylamine was directly monitored by a IR probe in situ. On the other hand, the self-healing effect of the alkyd primer coating doped with nanocontainers loaded with dodecylamine was demonstrated in situ by SVET and EIS measurements.