Dresden 2017 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 56: Hydrogels and Microgels I

CPP 56.8: Vortrag

Donnerstag, 23. März 2017, 12:30–12:45, ZEU 260

A mesoscale hydrodynamic simulation study of polymer dynamics in responsive microgels — •Ali Ghavami, Hideki Kobayashi, and Roland G. Winkler — Institute for Advanced Simulation, Forschungszentrum Juelich GmbH, 52425 Juelich, Germany

We analyze the internal polymer dynamics in microgel systems under different swelling conditions. A microgel particle consists of tetra-functionally crosslinked linear polymers in solution, which undergoes conformational changes in response to the external stimuli. Here, a broad range of microgel sizes, extending from hydrophobically collapsed to charged swollen particles, are considered and hydrodynamic interactions are accounted through multiparticle collision dynamics method.The polymer dynamics is analyzed in terms of the monomer mean square displacement and the intermediate scattering functions. For microgels in good solvent, the scattering function decays in a stretched-exponential manner, with a decay rate exhibiting a crossover from a collective diffusive-like dynamics at low wavenumbers to a hydrodynamic-dominated dynamics at larger wavenumbers. There is little difference between the intermediate scattering functions of microgels under good solvent conditions and strongly swollen gels, but strongly collapsed gels exhibit a faster decay at short times as the hydrodynamic interactions become screened. In addition, we present results for the dynamics of the crosslinks, which exhibit an unexpected, semiflexible polymer-like dynamics.