Dewetting of an Evaporating Thin Liquid Film: Heterogeneous Nucleation and Surface Instability

Film rupture as the initial stage of dewetting is investigated for a volatile, spin-coated nonwetting film. During structure formation in the liquid film the film thickness is continuously reduced via evaporation. The dynamical character of the experiment allows the study of hole formation caused by distinct rupture mechanisms occurring at different film thicknesses. Both heterogeneous nucleation for thick films as well as spinodal dewetting for film thickness below 10 nm have been observed. The balance between both processes can be shifted by controlling the ambient humidity. The structures resulting from film rupture are quantified with respect to their different geometrical properties. For the first time we find that spinodal dewetting is caused by destabilizing polar interactions.