Paper Number
IR16
Session
Interfacial Rheology
Title
Droplet evaporation on soft solid substrates
Presentation Date and Time
October 10, 2022 (Monday) 5:05
Track / Room
Track 5 / Sheraton 2
Authors
- Charitatos, Vasileios (University of Minnesota, Department of Chemical Engineering and Materials Science)
- Kumar, Satish (University of Minnesota, Department of Chemical Engineering and Materials Science)
Author and Affiliation Lines
Vasileios Charitatos and Satish Kumar
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455
Speaker / Presenter
Kumar, Satish
Keywords
theoretical methods; colloids; interfacial rheology
Text of Abstract
Droplet evaporation on soft solid substrates is relevant to applications such as fabrication of microlenses and controlled particle deposition. Here, we develop a lubrication-theory-based model to advance fundamental understanding of the important limiting case of a planar droplet evaporating on a linear viscoelastic solid. A set of partial differential equations describing the time evolution of the liquid–air and liquid–solid interfaces is derived and solved with a finite-difference method. A disjoining-pressure/precursor-film approach is used to describe contact-line motion, and the one sided model is used to describe solvent evaporation. Parametric studies are conducted to investigate the effect of solid properties (thickness, viscosity, shear modulus, wettability) and evaporation rate on droplet dynamics. Our results indicate that softer substrates speed up droplet evaporation due to prolonged pinning of the contact line. Results from our model are able to qualitatively reproduce some key trends observed in experiments. Due to its systematic formulation, our model can readily be extended to more complex situations of interest such as evaporation of particle-laden droplets on soft solid substrates.