Formation of labyrinthine drying patterns in 2D model porous media
| When |
Dec 08, 2017
from 10:45 to 12:00 |
|---|---|
| Where | room 116 |
| Attendees |
Pascal Panizza |
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The evaporation of liquid dispersions is important in civil engineering as salt weathering damages the built environment and in material science for the design of novel smart materials at the micro- and nano-scale. Yet, this issue has remained elusive notably because of complex couplings between the formation of solid deposits and the various transport phenomena that occur during drying. To address this problem, we investigate drying of colloidal suspensions or surfactant solutions confined in 2D porous model media allowing us to overcome optical limitation inherent to bulk systems. We observe the formation of thin solid films that connect adjacent posts to form a maze. Our experiments show that the formation dynamics of these out of equilibrium patterns is controlled by a regular succession of Haines jumps. Identifying the elementary mechanisms yielding the formation of the deposits at the pore scale, we establish a pore-network model that well captures the final topology and formation dynamics of the observed labyrinthine structures. Using simple arguments, we predict the topological changes in the drying pattern at the pore scale as a function of the relevant geometrical parameters (sample thickness and contact angle that the liquid makes with the substrate). Our experiments confirm our theoretical predictions.