Mechanical instability induced by complex liquid desiccation

The drying of sessile drops of a complex liquid can lead to various types of surface distortion and final shapes. Here we investigate the desiccation of drops for two different systems: colloidal particle suspensions and polymer solutions. During solvent loss, the non-volatile compounds accumulate near the vapor/drop interface and, depending on the experimental conditions, they can form a permeable rigid skin (a gelled or glassy skin) displaying a buckling instability. In some cases secondary instabilities also take place. Although the nature and the physicochemical properties of the two systems are quite different, the shape evolutions show a remarkable similarity. A good agreement is found with a description based on the comparison of the characteristics times involved in the problem. To cite this article: L. Pauchard, C. Allain, C. R. Physique 4 (2003).