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

Abstract

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. [S0031-9007(98)05676-2]

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

“…S p B 0 and S ap \ 0 are the polar and apolar components of the total spreading coefficient, S = S ap +S p . Experimental systems corresponding to this case are for instance water on graphite [21] and on most polar substrates like PMMA, corneal epithelium, PVC or polystyrene [31,39]. Introducing the dimensionless parameters.…”

“…They occur in the range of metastable and linearly unstable film thicknesses, respectively, [2,5,7,8,12,13,[19][20][21]. To distinguish the two mechanisms different procedures have been proposed.…”

“…On the other hand, ordered and disordered arrangements of holes are taken as caused by surface instability and nucleation, respectively [12,19,21]. The analysis instruments used to determine the order of a pattern range from the pair correlation function for the set of points formed by the hole centers [21] to Minkowski measures that give higher order characteristics of the same set of points [12].…”

Morphology changes in the evolution of liquid two-layer films

“…The main focus lies thereby on front instabilities of moving contact lines 1,2,3 or on instabilities of the free liquid-gas interface of a flat film 4,5,6 .…”

Nanopatterns induced by pulsed laser irradiation on the surface of an Fe-Al alloy and their magnetic properties

“…The smoothly curved shape of the surface and the internal roughness of the periodic nanostructure suggest that the formation is attributed to the dewetting process. 24 Figures 3(b) and 3(c) show diffraction patterns along the [110] direction given by arrows b and c, respectively, given in Fig. 3(a).…”