Enhancement corrosion resistance of (γ-glycidyloxypropyl)-silsesquioxane-titanium dioxide films and its validation by gas molecule diffusion coefficients using molecular dynamics (MD) simulation

Based on silsesquioxanes (SSO) derived from the hydrolytic condensation of (γ-glycidyloxypropyl)trimethoxysilane (GPMS) and titanium tetrabutoxide (TTB), hybrid films on aluminum alloy (AA), film-GPMS-SSO (f-GS) and f-GS-TTB_i% (f-GSTT_5%-25%, i = 5, 10, 15, 20 and 25 wt%), were prepared and tested by electrochemical measurements with typical potentiodynamic polarization curves. The I_corr values of the samples were significantly lower, comparing with the I_corr values of the f-GS, AA and f-GS modified tetraethoxysilane (TEOS) in the previous study, which implies that the TTB_5%-25% (TiO2) additions in the coatings indeed enhance the electrochemical corrosion resistance. Correlations between the film structures and anticorrosion properties were discussed. To validate the corresponding anticorrosion experiment results, different 3D-amorphous cubic unit cells were employed as models to investigate the self-diffusion coefficient (SDC) for SO₂, NO₂ and H₂O molecules by molecular dynamics (MD) simulation. All of the SDCs calculated for SO₂, NO₂ and H₂O diffusing in f-GSTT_5%-25% cells were less than the SDCs in f-GS. These results validated the corresponding anticorrosion experiment results.