We have measured the contact angle of microsized and nanosized alkane droplets partially wetting a model substrate using true noncontact atomic force microscopy. The large range of droplet sizes accessible using this technique allowed us to determine the contact line curvature dependence of the contact angle with unprecedented accuracy. Whereas previous studies aimed at explaining such a dependence by a line tension effect, our results and calculations on a model system exclude such an effect and point to an extreme sensitivity to weak substrate heterogeneities confirmed by numerical simulations.

The Seebeck coefficients of the non-aqueous electrolytes tetrabutylammonium nitrate, tetraoctylphosphonium bromide and tetradodecylammonium nitrate in 1-octanol, 1-dodecanol and ethylene-glycol are measured in a temperature range from T =30 to T = 45 • C. The Seebeck coefficient is generally of the order of a few hundreds of microvolts per Kelvin for aqueous solution of inorganic ions. Here we report huge values of 7 mV/K at 0.1M concentration for tetrabutylammonium nitrate in 1-dodecanol. These striking results open the question of unexpectedly large kosmotrope or "structure making effects" of tetraalkylammonium ions on the structure of alcohols.