This thesis concerns the drying of thin aqueous solution in a cosmetic context, the stability and texture of such film being crucial for cosmetic applications. We study the drying of cosmetic thin films of initial thickness between 20 and 100 microns, mainly made from organic polymers soluble in water and an anti-microbial preservative. The initial viscoelastic properties of these formulations are analyzed before plating, using a temperature-controlled rheometer. Films are deposited on various substrates in a controlled atmosphere, drying is followed in situ by means of a gravimetric analytical balance. We examine the influence of various physico-chemical parameters that govern the film/skin interface during drying such as humidity, temperature, film composition, nature of the support, etc. During the drying, we have observed the swelling of the films at large times that we have interpreted as a slow evolution of the residual polymeric matrix. We have also observed the formation of craters while drying leading to a texturation of the surface. We have shown using a simple diffusion model that such structure was caused by a demixtion transition governed by the preservative agent. Finally it lead to the development of a more complete model of drying for thin films that accounts for the different physical mechanism at the heart of the dynamics.
