Dresden 2017 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster: Polymer Networks and Dynamics

CPP 17.7: Poster

Montag, 20. März 2017, 18:30–21:00, P1C

Thermal, collective and self-diffusion of linear and cross-linked PMMA — •Bastian Pur¹, Werner Köhler¹, Martin Schneider², Klaus Huber², Alexei F. Privalov³, and Max Schäfer³ — ¹Physikalisches Institut, Universität Bayreuth, 95440 Bayreuth, Germany — ²Physikalische Chemie, Universität Paderborn, 33098 Paderborn, Germany — ³Institut für Festkörperphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany

Present theories for polymer thermophoresis discuss two theoretical models: draining coil (Rouse) and nondraining coil (Zimm). In order to discriminate between these models we have startet a comparative investigation of linear chain polymers and cross-linked polymers (microgels). The linear polymer samples are poly(methyl-methacrylate) (PMMA) and the microgel samples are PMMA cross-linked with different amounts of ethylenglycole-di-methacrylate (EGMA). In either case toluene is used as solvent. By means of a transient holographic grating technique we obtained the Fickian diffusion coefficient D, the thermal diffusion coefficient D_T and the Soret coefficient S_T as functions of the polymer concentration c. Using NMR diffusometry in ultrahigh static magnetic field gradients we have determined the self-diffusion coefficient D_s. For c → 0 the thermophoretic mobilities of the linear polymers and the microgels with 3.5% EGMA are identical within experimental accuracy. The concentration dependence of D_T is, however, different, with a more pronounced slowing down of the microgel. Against our assumption, D_s of the microgel shows an even stronger concentration dependence, indicating different fricition mechanisms.