Regensburg 2022 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 12: Poster 1

CPP 12.1: Poster

Montag, 5. September 2022, 18:00–20:00, P1

Janus particles: Challenges in the preparation process and analysis of their thermophoretic self-propulsion — •Franziska Jakob and Regine von Klitzing — Institute for Condensed Matter Physics, Technische Universität Darmstadt, D-64289 Darmstadt

Active colloidal particles with different functionalities at their opposite sides are named Janus particles - motivated by the Roman mythological god. One possible propulsion mechanism is thermophoretic self-propulsion. When laser light (λ = 532 nm) illuminates a gold-capped particle, a local temperature gradient is generated along the particle surface due to surface plasmon excitation of the gold cap. This gradient perturbs the equilibrium conditions of the surrounding medium and finally leads to particle self-propulsion.

This contribution focuses on various preparation processes of self-thermophoretic gold-polystyrene (Au-PS) microswimmers. The influence of the preparation technique on the gold cap size and the resulting self-thermophoretic behavior of the Janus particle will be presented. For this purpose, Janus particles are prepared either by metal sputtering, thermal evaporation, or by a combination of gel trapping technique and metal sputtering. With scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), the dimension of the gold cap was investigated. Dark-field microscopy (DFM) combined with a LabView program enables real-time tracking of the Janus particles. The study shows that the preparation method strongly affects the gold cap size of the Janus particles and thus influences their self-thermophoretic velocity.