Molecular dynamics simulation on the shielding effect of aminopropyl trimethoxysilane film on corrosive media

Abstract Aminopropyl trimethoxysilane (APTMS) was used as a silane reagent, and oxygen and water were set as corrosion media, respectively. The mean square displacement (MSD) of oxygen and water molecules in silanized films with different cross-linking degrees (APTMS-OH-1, APTMS-OH-4, APTMS-OH-8, and APTMS-OH-12) were investigated by molecular dynamics simulation to characterize the corrosion inhibition effect of silanized films in different corrosion media. The results showed that compared with in air, the MSD of oxygen and water molecules in silane film was significantly reduced, which indicated that silane film could prevent the diffusion of corrosive medium, thus protecting material. Silane films with various crosslinking degrees have different shielding effects on oxygen and water molecules. The MSD of oxygen in silane films with different crosslinking degrees was: APTMS-OH-1>APTMS-OH-4>APTMS-OH-12>APTMS-OH-8, while the MSD of water in silane films with different crosslinking degrees was: APTMS-OH-1>APTMS-OH-4≈APTMS-OH-12>APTMS-OH-8. The MSD of both oxygen and water molecules was the lowest in silane films with a crosslinking degree of 8, which showed that silane films had the highest shielding effect.