Eur. Phys. J. E 7, 31-34 (2002)
DOI: 10.1140/epje/i200101169
Solvent evaporation of spin cast films: "crust" effects
P.G. de GennesCollège de France, 11 place M. Berthelot, 75231 Paris Cedex 05, France pgg@espci.fr
(Received 13 November 2001)
Abstract
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
