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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 50: Poster Session III

CPP 50.48: Poster

Dienstag, 17. März 2020, 14:00–16:00, P1C

Drying of shallow sessile droplets — •Swati Kaushik, Stefan Karpitschka, and Oliver Bäumchen — Max Planck Institute for Dynamics and Self-Organization (MPIDS), Am Fassberg 17, 37077 Göttingen, Germany

The evaporation of sessile droplets on solid surfaces is an everyday phenomenon. The quantitative description of the evaporation dynamics is not only of interest from a fundamental perspective, but also highly relevant for practical applications such as coating technologies and inkjet printing. Here, we investigate the evaporation dynamics of shallow sessile droplets of pure n-Tetradecane on functionalized Si-wafers. We use an optical interference microscopy technique to construct the droplet profile over the course of drying process along with the dynamic measurement of the contact angle θ . The contact radius and droplet volume are also quantified taking into account the spherical cap approximation. This technique allows for measuring contact angles with a precision of 0.1^∘. The droplet dynamics are studied for different substrate temperatures and surface functionalization during the early stages of evaporation where the drop stays pinned to the substrate. We find a good agreement of the experimental results with theoretical models for diffusion-based evaporation. In addition, it is found that the depinning time varies with the initial contact angle and substrate temperature. We also report an interesting linear dependency of the rate at which the contact angle changes, dθ/dt, on the inverse of the initial contact area in the limit of small contact angles.