Investigating the Mechanisms of Rupture and Dewetting of Quiescent Thin Films

Controlling and predicting rupture and dewetting of quiescent thin water films, hundreds of microns thick, was studied experimentally. Wax, polycarbonate, steel and aluminium surfaces were immersed in water; the water level was lowered to form thin films above the surfaces. Spontaneous film rupture only occurred on wax, a low-energy surface. Films ruptured at the edges of the other—high-energy—surfaces. Increased surface roughness decreased chances of rupture and dewetting in the film. Introducing large wax or steel protrusions (on the order of millimetres) on smooth surfaces showed films rupturing above the protrusions and adhering to them; further thinning caused rupture and dewetting away from the protrusions. Entrapped air bubbles, injected through the surface and into the film, ruptured as they breached the film surface to form stable holes in the film if it was sufficiently thin. Entrapped air was the best means of rupturing films on all surfaces.MAS