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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 52: Wetting, Fluidics and Liquids at Interfaces and Surfaces III (joint session CPP/DY)

CPP 52.4: Talk

Thursday, March 30, 2023, 15:45–16:00, MER 02

Dilute suspensions of chemically active particles in thin liquid films — •Tilman Richter, Paolo Malgeretti, and Jens Harting — HELMHOLTZ-INSTITUT ERLANGEN-NÜRNBERG FÜR ERNEUERBARE ENERGIEN, Erlangen, Germany

Thin liquid films are important for many microfluidic applications such as printing or coating of e.g. printable electronics or photovoltaic cells as well as so called lab-on-a-chip devices. Also in catalysis at liquid interfaces thin film dynamics are important. It is well known that a thin film on a solid substrate can be unstable and droplet formation may arise.

The dynamics of thin liquid films and their instability has been the subject of intensive experimental, analytical, and numerical studies, the latter often based on the thin film equation. We propose a set of newly developed equations for the influence of chemical active colloids suspended in a thin liquid film based on the lubrication and Fick-Jackobs approximation. For this novel set of equations we perform a linear stability analysis (LSA) that reveals surprisingly interesting dynamics. We identify the subset of parameters for which the thin film becomes stable i.e. is not rupturing, as well as a variety of different dominating wave-modes. This allows us to control not only the stability but also the droplet size distribution after film rupture, as well as the time it takes for an initially flat film to rupture.

In order to assess the asymptotic state of the thin film, the LSA results are compared against numerical simulations using the Lattice Boltzmann method.