Berlin 2018 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 3: Complex Fluids and Colloids I (joint session CPP/DY)

DY 3.11: Vortrag

Montag, 12. März 2018, 12:15–12:30, C 264

Ultrasoft colloids under pressure driven flow — •Deepika Deepika and Arash Nikoubashman — Institute of Physics, Johannes Gutenberg University, Staudingerweg 7, 55128 Mainz, Germany

Star-shaped polymers show a continuous change of properties from flexible linear chains to soft colloids, as the number of arms is increased. To investigate the effect of macromolecular architecture on the flow behavior, we employed computer simulations of single star polymers as well as of mixtures of star and linear polymers under dilute conditions. Hydrodynamic interactions were incorporated through the multi-particle collision dynamics (MPCD) technique, while a bead-spring model was used to describe the polymers. At rest, the polymers were distributed homogeneously in the slit channel, irrespective of the number of arms. Once flow was applied, however, we found that the stars migrated more and more towards the channel center as the number of arms increased and the polymers became more rigid. These findings are in contrast to previous findings for deformable vesicles, where the softer particles moved to the channel center. We surmise that the observed behavior for polymers is due to effective arm stretching and hydrodynamic repulsion with the channel walls. In the star-chain mixtures, we found a flow-induced separation between stars and chains, with the stars being in the center and the chains closer to the walls. The results from our study give valuable insights for designing microfluidic devices for separating particles based on their rigidity.