Berlin 2015 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 47: Microswimmers, Active Liquids I (joint CPP/BP/DY)
BP 47.6: Vortrag
Donnerstag, 19. März 2015, 17:30–17:45, PC 203
Formation, compression and surface melting of colloidal clusters by active particles — •Felix Kümmel1, Parmida Shabestari1, and Clemens Bechinger1,2 — 12. Physikalisches Institut, Universität Stuttgart, D-70569 Stuttgart, Germany — 2Max-Planck-Institut für Intelligente Systeme, D-70569 Stuttgart, Germany
Artificial active swimmers, i.e. Janus particles, suspended in a critical binary mixture, are capable of a self-diffusiophoretic motion upon illumination [1][2]. In previous experiments, the dynamics of such swimmers close to walls and periodic arrays of rigid obstacles has been investigated [1]. Here, we experimentally examine the structural changes in a mixture of passive and a small number of active colloidal particles of equal diameters in a two-dimensional system. With increasing passive particle area fraction, we observe the formation of clusters with passive particles in the interior and active particles at their boundaries. Further increase of the passive area fraction leads to the merging and compression of such clusters and eventually to local melting of crystalline regions by enclosed microswimmers. Our results demonstrate that the addition of only a small amount of active particles largely changes the structure and the dynamics of colloidal suspensions.
[1] VOLPE G, BUTTINONI I, VOGT D, KÜMMERER H J AND BECHINGER C 2011 MICROSWIMMERS IN PATTERNED ENVIRONMENTS SOFT MATTER 7, 8810 (2011) [2] B. TEN HAGEN, F. KÜMMEL, R. WITTKOWSKI, D. TAKAGI, H. LÖWEN, AND C. BECHINGER, NATURE COMMUNICATIONS 5 (2014)