Enhanced corrosion protection of copper in saline environments using bio-nanocomposite coatings based on chitosan and chitosan Schiff base.

An in-depth study focuses on developing new environmentally friendly bio-nanocomposites, by incorporating SrTiO (STO) ceramic nanoparticles into matrices of chitosan and its derivatives, aiming to use them as protective coatings against corrosion. The various stages of this study include the cross-linking of chitosan, the synthesis of Schiff base chitosan, the cross-linking of Schiff base chitosan, and the preparation of nanocomposite coatings. The coatings' structure and composition were analyzed using different methods, including Fourier Transform Infrared Spectroscopy - Attenuated Total Reflectance (FTIR-ATR), X-ray Diffraction (XRD), Transmission Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (TEM-EDX), and Scanning Electron Microscopy (SEM). In addition, Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP) measurements were carried out to assess the inhibitory efficacy of chitosan crosslinked with epichlorohydrin (Cs-Ep), epichlorohydrin-crosslinked chitosan-salicylaldehyde Schiff base (CS-S-Ep) and CS-Ep-STO and CS-S-Ep-STO nanocomposite coatings, as well as the long-term protection durability of CS-S-Ep-STO. These techniques revealed a significant reduction in corrosion current density after chemical modification of chitosan and incorporation of SrTiO (STO) nanoparticles into CS-Ep and CS-S-Ep matrices, confirming a notable improvement in the inhibitory efficiency of these coatings against copper corrosion in a saline environment. Computational modeling methods like Density Functional Theory (DFT), Molecular Dynamics (MD), and Monte Carlo (MC) simulations reinforced these results by demonstrating efficient adsorption of CS-S-Ep-STO nanocomposites on metal surfaces through the interaction with heteroatoms present in the functional groups (-C=N-, -C-O-, -OH) and STO nanoparticles. The present study's findings provide key information for developing innovative protective coatings, highlighting the potential of chitosan-based nanocomposites and derivatives, particularly with SrTiO incorporation, in mitigating metal surface corrosion in aggressive environments.