Eur. Phys. J. E 7, 31-34 (2002)
Solvent evaporation of spin cast films: "crust" effectsP.G. de Gennes
Collège de France, 11 place M. Berthelot, 75231 Paris Cedex 05, France email@example.com
(Received 13 November 2001)
When a glassy polymer film is formed by evaporation, the region near the free surface is polymer rich and becomes glassy first, as noticed long ago by Scriven et al. We discuss the thickness of this "crust" and the time interval where it is present -before freezing of the whole film. We argue that the crust is under mechanical tension, and should form some cracks. This may be the source of the roughness observed on the final, dry films, when the solvent vapor pressure is high (and leads to thin crusts).
66.10.-x - Diffusion and ionic conduction in liquids.
68.60.-p - Physical properties of thin films, nonelectronic.
83.80.Rs - Polymer solutions.
82.70.-y - Disperse systems; complex fluids.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002