In‐depth investigation of incremental layer build‐up from dried deposited droplets

Abstract

AbstractThis study presents an approach to closely investigate the process of incremental layer build‐up from convectively dried sessile droplets. In a droplet‐by‐droplet manner, three layers of sodium benzoate solution droplets are consecutively applied on a glass substrate and successively dried in a laboratory‐scale drying chamber. The morphology of the simplified layer structure that incrementally forms from the individual deposits is analyzed via white‐light interferometry, after every addition of a new droplet. Furthermore, complementary X‐ray micro‐tomography measurements of the deposits were carried out to monitor inner structure development. Recurring steps and phenomena throughout the experimental build‐up process were identified and could be characterized through these methods. Moreover, these phenomena could be linked to specific combinations of droplet positioning and drying conditions. Finally, the overall influence of convective drying parameters as well as droplet properties on the layer formation process was investigated with regard to morphology and porosity.