Specific detection of interactions between uncharged surfaces in different solvents: high-resolution imaging by chemical force microscopy

The detection of hydroxyl-groups by chemical force microscopy is investigated in two contrasting solvents: water and hexadecane. Gold-coated cantilevers were chemically modified in a defined way by self-assembly monolayers (SAMs) formed by mercapto-undecanol. The samples employed consisted of ultraflat gold surfaces terminated by hydroxyl- and methyl-groups. Both surface terminations were present on the sample surface in a well-defined pattern obtained by micro-contact printing (mu CP). High-resolution lateral force microscopy (LFM) was conducted in both solvents. These LFM measurements were complemented by measurements of the adhesion forces on the same substrates. In contrast to water, the empolyment of hexadecane, it enables specific detection of hydroxyl-groups and clear interpretation of the friction contrast.