Regensburg 2022 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 9: Thin Film Properties: Structure, Morphology and Composition (XRD, TEM, XPS, SIMS, RBS, AFM, ...) 3

DS 9.4: Vortrag

Dienstag, 6. September 2022, 10:15–10:30, H14

Phase behavior of dumbbell monolayers obtained via Langmuir-Blodgett-like Brownian dynamics simulations — •Anton Lüders, Rouven Stuckert, Ellen Zander, Alexander Wittemann, and Peter Nielaba — Universität Konstanz, Konstanz, Deutschland

We explore the structure formation and the phase behavior of thin films of dumbbell colloids. For this, we first determine empiric formulas for the microscopic diffusion coefficients of dumbbells using a bead-shell approach. These diffusion coefficients are used to perform two-dimensional Brownian dynamics (BD) simulations where the area fraction of the system is adjusted via movable barriers at the boundaries of the simulation box. The results of the simulations are compared to Langmuir-Blodgett experiments with dumbbell monolayers at the air/water interface. Using Voronoi diagrams and the Voronoi cell shape factor, the influence of the area fraction on the structure of the monolayers is investigated. The simulations and the experiments show - in excellent agreement with each other - that an increase of the area fraction leads to a higher percentage of domains containing particles with six nearest neighbors. Especially in dense systems, these domains can consist of aligned particles with uniform Voronoi cells. Thus, the increase of the area fraction enhances the order of the monolayers. The remarkable qualitative agreement of the simulations and the experiments indicates a versatile way of characterizing colloidal monolayers by BD simulations which opens up perspectives for application to a broad range of nanoparticle-based thin film coatings.