title: Thinning and rupture of liquid films by moving slot jets.
abstract: We present systematic experiments of the rupture and dewetting of thin films of a nonvolatile polar liquid on partially wetting substrates due to a moving slot jet, which impinges at normal incidence. The relative motion was provided by a custom-built spin coater with a bidirectionally accessible axis of rotation that enabled us to measure film thickness profiles in situ as a function of substrate velocity using dual-wavelength interference microscopy. On partially wetting polymeric substrates, dry spots form in liquid films with a residual thickness well below 1 μm. We measured the density of dry spots as well as the density and size distribution of the residual droplets as a function of film thickness. In a certain parameter range, the droplet distributions exhibit pronounced anisotropy due to the effect of long-range shear stresses on the dewetting rim instability. We find robust power-law scaling relations over a large range of film thicknesses and a striking similarity to literature data obtained with ultrathin polymer melt layers on silicon substrates.
authors.affiliation: Mesoscopic Transport Phenomena Group, Department of Applied Physics, Eindhoven University of Technology , Den Dolech 2, 5612AZ Eindhoven, The Netherlands.
authors.forename: Christian W J
authors.initials: CW
authors.lastname: Berendsen
authors.forename: Jos C H
authors.initials: JC
authors.lastname: Zeegers
authors.forename: Anton A
authors.initials: AA
authors.lastname: Darhuber