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Drying of colloidal suspensions in confined geometries
We investigate the concentration process of dilute colloidal suspensions up to dense states in two different confined geometries.
The first geometry corresponds to a confined droplet between two parallel plates. The second one, the "microevaporator", is a microfluidic format of a continuous pervaporation experiment.
These two confined geometries allow the use of simple models, and the analysis of drying of mixtures permits, a priori, to access both kinetic and thermodynamic informations (activity & mutual diffusivity).
We studied different "soft matter" systems in these two geometries : (i) tribloc copolymers (pluronics) ; (ii) monodisperse colloids (sulfate latex, 500nm), (iii) and charged dispersions of silica nanoparticles NPs (Ludox, 26nm). We will detail in each case some features of the drying process. Namely, we will show in these three systems, that it is possible (i) to access simply and quantitatively to phase diagrams of copolymers using the confined droplet method ; (ii) that we can form colloidal crystals using the microevaporation technique ; and (iii) Finally, we will show using microfocused SAXS experiments performed at ESRF, that the microevaporation of the charged NPs dispersion also leads to dense organized colloidal states. In these two last cases, we will also point out the crucial role played by the elestrostatic interactions on the concentration process.
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Contact : mathilde.reyssat[at]espci.fr