Narendra Kumar Agnihotri

TL;DR: It is shown that, in addition to morphology and free energy, the number density of local maxima in the film profile can also be used to identify the early, late, and intermediate stages of spinodal phase separation.

Abstract: In this chapter, we will study the kinetics of dewetting, that is, the appearance and growth of dry (uncovered) portions on surfaces covered with liquids. This process is analogous to the process of phase separation, which has been discussed in previous chapters. The liquid cover breaks as a result of sustained local thinning due to the flow of liquid from thinner to thicker parts. This flow, which is the main operative mechanism for dewetting, can be achieved by a variety of mechanical means, for example, impact by a gas jet or dust particles. In some cases, this uphill liquid flow can also be spontaneous under the influence of chemical-potential gradients. In this case, dewetting occurs even if the system is free of any destabilizing mechanical input. This spontaneous dewetting is dependent on the thickness of the liquid cover. The thickness of the intervening film (see Figure 6.1) has to be small enough for thefilm surface to feel the attraction of molecules in the solid surface and get pulled (thin) toward the solid surface. Naturally, this thickness has to be less than the effective range of intermolecular interactions (∼100 nm).