Berlin 2015 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 33: P5: Microswimmers, Active Liquids

CPP 33.2: Poster

Tuesday, March 17, 2015, 14:00–16:00, Poster C

Self-propulsion of Janus particles near a polymer functionalized surface — •Mojdeh Heidari and Regine von Klitzing — Stranski Laboratorium für Physikalische und Theoritische Chemie, Inst. für Chemie TU Berlin, Straße des 17. Juni, 10623 Berlin, Germany

Active colloidal suspensions are consisting of particles with dimensions ranging from hundreds of nanometer to tens of micrometer. These particles are able to move autonomously under out-of-equilibrium conditions by converting the energy of their environment into directed motion. So far, the motion of microswimmers has been investigated close to a glass slide, whereas the interactions between particles and the substrate are often neglected. However, these interactions are expected to play a significant role in the motion of microswimmers.

In this study we explore the motion of Janus-type microswimmers close to a glass slide which is functionalized with thermoresponsive PNIPAM brushes. Janus particles are polystyrene microbeads half coated with Au and undergo self-propulsion by taking advantage of thermophoretic effect under laser illumination. The remarkable advantage of such Janus particles is that their self-propelled motion can be switched on and off on demand by adjusting laser intensity. Structural properties of polymer brush layer on the substrate such as roughness, thickness and grafting density has been varied and the respective influence of such variations on the motion of microswimmers has been addressed.