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arXiv · 2311.04728

Molecular Rotors for In Situ Viscosity Mapping during Evaporation of Confined Fluid Mixtures

Florence Gibouin·Dharshana Nalatamby·Pierre Lidon·Yaocihuatl Medina-Gonzalez
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Abstract

Numerous formulation processes of materials involve a drying step, during which evaporation of a solvent from a multi-component liquid mixture, often confined in a thin film or in a droplet, lead to concentration and assembly of non volatile compounds. While the basic phenomena ruling evaporation dynamics are known, a precise modeling of practical situations is hindered by the lack of tools for local and time-resolved mapping of concentration fields in such confined systems. In this article, the use of Fluorescence Lifetime Imaging Microscopy and of Fluorescent Molecular Rotors is introduced as a versatile, in-situ and quantitative method to map viscosity and concentration fields in confined, evaporating liquids. More precisely, the cases of drying of a suspended liquid film and of a sessile droplet of mixtures of fructose and water is investigated. Measured viscosity and concentration fields allow to characterize drying dynamics, in agreement with simple modeling of the evaporation process.

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Florence Gibouin, Dharshana Nalatamby, Pierre Lidon, Yaocihuatl Medina-Gonzalez. 2023-11-08. Molecular Rotors for In Situ Viscosity Mapping during Evaporation of Confined Fluid Mixtures. https://doi.org/10.1021/acsami.3c16808

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