Wettability of heterogeneous substrates

Incomplete organic monolayers grafted on silicon wafer are characterized by spectroscopic ellipsometry (SE) using the Bruggeman effective-medium approximation. The formation of the monolayer, as a condensed liquid (LC*) phase, is investigated. The time evolution of the surface fractions occupied by the different phases allows the determination of a reaction model and of the associated thermodynamic constants. Furthermore, the high spacial resolution spectroscopic ellipsometry (HRSE) is used to study the spreading of silicon oils on such heterogeneous substrates. A simple model is proposed, in agreement with the experimental results, showing that the inverse of the diffusion coefficient of the liquid molecules is proportional to concentration of the heterogeneities.