Molecular forces caused by the confinement of thermal noise.
We have investigated spontaneous surface instabilities of very thin polymer films. Film stability and the wavelength of the dominating unstable mode were found to depend sensitively on the media adjacent to the film. Our experimental results cannot be explained by van der Waals interactions alone. To account for the presence of an additional destabilizing force, we propose that the geometrical confinement of thermally excited acoustic waves gives rise to a force that is strong enough to destabilize thin films. This thermoacoustic effect is of similar magnitude as van der Waals forces.
Morariu
Mihai D
MD
Department of Polymer Chemistry and Materials Science Center, University of Groningen, Nijenborgh 4, NL-9747 AG Groningen, The Netherlands.
Schäffer
Erik
E
Steiner
Ullrich
U