Investigating the effect of silane modification of chitosan on the anticorrosion performance of epoxy primer coating using computational simulation technique

Abstract The anticorrosion performance of silane-modified chitosan/epoxy primer coatings was evaluated using quantum chemical computations and molecular dynamics simulation. The coating formulation was based on diglycidyl ether of bisphenol A (DGEBA) epoxy cured with 1,3- benzenediamine (BDA). Chitosan biopolymer nanoclusters were used as filler, and two different silane additives: tetraethoxysilane and (3- aminopropyl) trimethoxy silane were used as hydrophobic modifiers. Mild steel surface was theoretically constructed, and 3.5 wt. % NaCl solution was simulated to represent seawater (marine water) as corrodent. The objective was to gain insight into the molecular/atomistic level of the coating/metal interface to be able to design high performance anticorrosion epoxy nanocomposite primer coating for marine application. The quantum chemical parameters as well as interactions between the silane-modified chitosan/epoxy coatings and mild steel surface were appraised. Computational results showed that the obtained quantum chemical parameters for the silane-modified chitosan are related to high corrosion protective capability. The adsorption energies (Eads) of the silane-modified chitosan/epoxy coating were observed to be higher than the unsilanized chitosan/epoxy and plain epoxy coatings. This implies that the silane-modified chitosan/epoxy coating is potentially more corrosion-resistant than the unsilanized chitosan/epoxy and plain epoxy coatings.