Inhibitor loaded functional HNTs modified coatings towards corrosion protection in reinforced concrete environment

In this work, the corrosion inhibitor sodium D-gluconate (SD) was successfully loaded into halloysite nanotubes (HNTs). After that, SD-HNTs-A3@CS/SA smart nanocontainers, achieving controlled release properties of inhibitors, were prepared by the layer-by-layer (LbL) self-assembly method. The BET analysis found that the pore size inside the halloysite nanotubes increased after etching by 3 mol/L H 2 SO 4 . According to the TG results, the loading capacity of corrosion inhibitors increased to three times of the original HNTs. The pH-responsive properties of nanocontainers could be demonstrated by UV–Vis spectroscopy under acidic/basic conditions. Furthermore, SD-HNTs-A3@CS/SA nanoparticles were embedded in epoxy resin to fabricate a smart composite coating . When the SD-HNTs-A3@CS/SA content was 2 %, the composite coating exhibited superior anti-corrosion performance towards steel corrosion in concrete simulation solution (containing 3.5 wt% NaCl), with its impedance at 0.01 Hz maintaining 6.4 × 10 6  Ω·cm 2 even after 18d of corrosion immersion. In addition, the anti-corrosion mechanism of SD for steel matrix was investigated by molecular modeling methods. These findings provide new insights into the preparation of smart coatings, expecting a wide range of applications in the corrosion protection of steel and other metals in reinforced concrete environments.