Monitoring the buckling threshold of drying colloidal droplets using water-ethanol mixtures.
We visualize the drying of droplets of colloids suspended in a mixture of two miscible solvents, namely water and ethanol. After a period of isotropic shrinkage, droplets suddenly buckle like elastic shells. For a fixed colloid solid fraction, the buckling threshold evolves as a function of ethanol content, due to changes of the solvent mixture physical properties, such as viscosity and evaporation rate. A simplified model predicting the qualitative behavior of the buckling threshold as a function of the initial ethanol mass fraction has been developed that fits well experimental results.
UMR CNRS 8612, Université Paris Sud, Châtenay-Malabry, France.
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Marty
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Tsapis