Mixed self-assembled monolayers of alkanethiolates on ultrasmooth gold do not exhibit contact-angle hysteresis.

We present the first study of mixed alkanethiolate SAMs on ultrasmooth gold surfaces. By eliminating surface roughness, it became possible, for the first time, to investigate wetting properties as a function of surface chemical composition. In three different surface compositions, it was found that contact-angle hysteresis apparently vanished. This suggests that surface chemical heterogeneity does not contribute to contact-angle hysteresis in mixed SAMs on ultrasmooth gold surfaces.