Phosphonic acid derivatives used in self assembled layers against metal corrosion

The preparation of self assembled molecular (SAM) layers needs molecules with a small hydrophilic and a big hydrophobic molecular parts. Special molecules were chosen where the head group was in all cases phosphonic group, but there were significant differences in the other molecular part. In one case a medium sized carbon chain with a single double bound, in the second case a long alkyl chain with fluoro atoms, and in the third case a polymer molecular part represented the hydrophobic molecular section. Our work was focused on the preparation and characterization of their SAM layers they formed on solid surfaces under the different conditions. The molecular films were deposited from organic solvents on different metal surfaces covered by oxide layer. In the case of the layer with double bounds, polymerization of the molecules on the surface with UV light was applied. The modified surfaces were characterized by the wettability and their anti-corrosion activity was determined in linear polarization experiments. According to the numerical results the wettability of the surfaces differed significantly, i.e., we successfully modify the solid surface with the coatings. The anticorrosion activity of the coated surfaces depends on the molecules used for layer deposition. The samples with fluoro-alkyl chains gave the best results, not only their contact angles were very high but their anti-corrosion effectiveness was the best.