SAMs may be defined as ordered molecular assemblies formed spontaneously by the adsorption of a surfactant with a specific affinity of its headgroup to a substrate Attraction to SAM area have increased over last 25 years although the studies started much earlier. Alkanethiol/gold systems which yield ordered, densely packed and stable SAMs are the mostly studied ones.
Fig. Schematical representation of a well-ordered alkyl phosphate SAM on Ta2O5.
The atomic structure and smoothness of substrate surface is very important in the quality of the SAM. There are several techniques to handle ultrasmooth metal oxide surfaces. Metal oxides with different surface structures have been used as substrates for formation of SAMs of organic films usually by immersing the substrates into the solutions of organic molecule. The binding of the SAMs to metal oxides do not seem so strong when compared to thiol/gold system, since SAMs on metal oxides are usually not resistant to solvent rinsing, especially to polar solvents such as ethanol. However several studies reported SAMs of carboxylic acids, alkyl/alkenephosphates, phosphonic acids on TiO2, Al2O3, Ta2O5, ZrO2 etc. The goal of our study is to prepare and characterize well ordered densely packed SAMs on metal oxide surfaces which are stable and reproducible.