AFM topography and friction studies of hydrogen-bonded bilayers of functionalized alkanethiols

Atomic Force Microscope (AFM) assisted nanografting was exploited to construct-in a liquid-well-defined nanoscale patches of amino- and carboxyl-terminated alkanethiols in a SAM matrix on an atomically flat gold (Au(111)) surface. By means of AFM the nanografted patches of these thiols were studied in detail by a combination of height and quantitative lateral friction measurements. The functionalized thiols form well-ordered self-assembled bilayers, with uniformly oriented and packed molecules, consisting of a first layer adsorbed to the gold surface via thiol-gold bonds, and a second layer stably bound to the first via COOH-HOOC or NH(2)-H(2)N intermolecular hydrogen bonds.