A novel technique was used to investigate the protection of copper with three types of nano-capsules polyelectrolyte modified halloysite nanotubes (PHN) polyelectrolyte modified SiO2 nanoparticles (PSN) and polyelectrolyte nano-capsules (PNC) capable of holding benzotriazole as corrosion inhibitor within a polyelectrolyte matrix and discharging it into the solution in a controlled way The increasing rate of inhibitor release from the studied nano-capsules follows the sequence PNC>PHN>PSN In addition the effect of polyelectrolyte shells was studied by PSN nano-capsules fabricated through layer-by-layer (L-b-L) assembly of PAH/PSS PAH/PMA and PAH/PMA + PSS polyelectrolyte bilayers The results indicate that the release of inhibitor depends on the polyelectrolyte shell components and the quantity of the corrosion inhibitor The release rate follows the sequence of PAH/PSS + PMA > PAH/PSS > PAH/PMA Effect of variation of solution parameters (pH temperature and stirring) on the concentration of the released inhibitor and ability of these doped particles to maintain appropriate conditions for smart corrosion protection have been considered (C) 2010 Elsevier Ltd All rights reserved