Chemical modification of alkanethiol monolayers for protecting iron against corrosion

Monolayers of alkanethiols CnH2n+1SH (CnT) adsorbed on an iron surface were prepared and characterized by polarization and impedance measurements in an aerated 0.5 M NaCl solution, contact angle measurement with a drop of water, and X-ray photo-electron spectroscopy. The protective efficiency P-K Of a C18T monolayer against iron corrosion in 0.5 M NaCl was 76.3%. Chemical modification of an 11-mercapto-1-undecanol HO(CH2)(11)SH (MUO) monolayer adsorbed on iron with octyltriethoxysilane C8H17Si(OC2H5)(3) (C8TES) was carried out to form a linear polymer film. The P-K value of the C8TES-modified MUO monolayer was 88.0% because the cathodic process of iron corrosion in the NaCl solution was suppressed by blocking diffusion of molecular oxygen. (C) 1997 Elsevier Science Ltd.