Polyelectrolyte-coated nanoporous carbon nanoparticles as pH-sensitive nanocontainers for controlled release of corrosion inhibitors.

Nanoporous carbon spheres with varying pore size distributions were created using a modified Stöber technique. The study examined how altering the carbonization heating rate affected the pore size and microstructure of the synthesized particles. The synthesized nanoporous carbons were considered as smart carriers for loading 2-mercaptobenzothiazole (MBT), and were encapsulated by coating with two different pairs of polyelectrolyte layers, PEI/PeAA and CS/PeAA. The characteristics of the synthesized and encapsulated samples were investigated by nitrogen adsorption, scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy. The total loading of MBT on nanoporous carbons with different pore size distributions was investigated via thermogravimetric analysis (TGA). The MBT release of the encapsulated samples under different pH conditions was assessed via UV‒Vis spectroscopy. Characterization of the pore size indicated that as the carbonization heating rate was increased from 5 to 10 and then to 15 °C/min, the pore diameter grew from 2.25 nm to 3.86 nm and 5.14 nm, respectively. The maximum loading capacity was achieved by the mean pore size distribution of 3.86 nm. Both of the applied polyelectrolyte shells exhibit favorable performance and provide controlled release under acidic and basic conditions. Nanoporous carbon with a suitable pore size distribution is a promising candidate for use as a smart carrier of corrosion inhibitors. Additionally, chitosan could be considered as an effective alternative to existing polyelectrolytes for creating smart anticorrosion particles.