Protection of zinc from corrosion by coverage with a hydrated cerium(III) oxide layer and ultrathin polymer films of a carboxylate self-assembled monolayer modified with alkyltriethoxysilanes

摘要

Ultrathin films of one- and two-dimensional polymers were prepared on a zinc electrode coated with a hydrated cerium(III) oxide Ce_2O_3 layer by modification of a 16-hydroxyhexadecanoate ion HO(CH_2)_(15)CO_2~- (HOC_(16)A~-) self-assembled monolayer (SAM) with alkyltriethoxysilanes. The protective efficiency, P of the film was determined by polarization measurements of the electrodes bare and covered with the polymer films in an oxygenated 0.5 M NaCl solution. The respective P values for the one-dimensional polymers of the HOC_(16)A~- SAM modified with octyltriethoxysilane C_8H_(17)Si(OC_2H_5)_3 (C_8TES) and octadecyltriethoxysilane C_(18)H_(37)Si(OC_2H_5)_3 (C_(18)TES) were 94.4 and 95.1%. The values for the two-dimensional polymers of the HOC_(16)A SAM modified with 1,2-bis(triethoxysilyl)ethane (C_2H_5)_3Si(CH_2)_2Si(C_2H_5)_3 plus C_8TES and C_(18)TES were 95.4 and 96.5%, respectively, indicating higher than those of the one-dimensional polymers. Structures of the polymer films were characterized by contact angle measurement with a drop of water and X-ray photoelectron and FTIR reflection spectroscopies.