On the importance of nucleation solutions for the rupture of thin liquid films

The process of dewetting of a thin liquid film is usually described using a long wave approximation yielding a single evolution equation for the film thickness. This equation incorporates an additional pressure term—the disjoining pressure—accounting for the effective interaction of the thin film with the substrate. We use the equation to study the evolution of unstable thin films examining the thickness ranges for linear instability and metastability for flat films, the families of stationary periodic and localized solutions and their linear stability. From this we conclude that within the linearly unstable thickness range exists a well defined subrange where finite perturbations are crucial for the time evolution and the resulting structures. In the remainder of the linearly unstable thickness range the resulting structures are controlled by the fastest flat film mode as was assumed up to now for all the linearly unstable thickness range. The results are shown for a disjoining pressure derived by coupling hydrodynamics to the diffuse interface model and for disjoining pressures combining destabilizing [stabilizing] polar short-range interaction with stabilizing [destabilizing] apolar long-range interaction. Finally, the implications for spinodal decomposition of a binary mixture are discussed.