An intelligent coating doped with inhibitor-encapsulated nanocontainers for corrosion protection of pipeline steel

- An intelligent coating is developed by doping BTA-encapsulated nanocontainers in an epoxy.
- The nanocontainers are distributed uniformly in the coating matrix.
- The encapsulated inhibitors self-release in response to the changes of solution pH.
- The intelligent coating effectively inhibits steel corrosion for a long-term immersion.

In this work, an intelligent coating was developed based on encapsulation of benzotriazole (BTA) inhibitors in prepared SiO2 nanoparticle based polyelectrolyte nanocontainers, and self-releasing of the inhibitors for corrosion inhibition to a pipeline steel in a chloride solution. Various morphological, compositional and structural characterizations demonstrate that the inhibitors BTA are effectively encapsulated in the nanocontainers, and the weight percentage of the loaded inhibitors is about 6.7 wt% in the nanocontainers. The nanocontainers can be dispersed uniformly in an industry-used epoxy coating under the testing condition, and do not change the coating properties, as shown by the identical glass-transitional temperature of the coatings containing various contents of nanocontainers. The encapsulated BTA can self-release for corrosion inhibition in response to changes of solution pH, as characterized by UV-vis spectroscopy. For the steel coated with the intelligent coating, the corrosion inhibition is time dependent upon self-releasing of the encapsulated inhibitors from the nanocontainers. With the increasing content of the nanocontainers in the coating, both the coating resistance and the corrosion resistance of the steel increase. The released inhibitors inhibit the steel corrosion by forming a layer of inhibitor-adsorptive film, which is detected on the steel surface after 30 days of immersion in the solution by elemental and structural characterizations.