Berlin 2018 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 15: Postersession III
BP 15.18: Poster
Dienstag, 13. März 2018, 14:00–16:00, Poster B
End of Cooperativity: Chain Exchange Kinetics in Mixed Polymeric Micelles with Partially Crystalline Cores — •Nico König1,2, Lutz Willner1, Thomas Zinn3, Vitaliy Pipich4, and Reidar Lund2 — 1Jülich Centre for Neutron Science JCNS and Institute for Complex Systems ICS, Forschungszentrum Jülich GmbH, Jülich, Germany — 2Department of Chemistry, University of Oslo, Oslo, Norway — 3ESRF - The European Synchrotron, Grenoble, France — 4Jülich Centre for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Garching, Germany
Here we present a kinetic study on the chain exchange in mixed polymeric micelles containing partially crystalline cores. We are interested in understanding how cooperative phenomena such as crystallization and melting affect the dynamics of self-assembled systems. As a model system we use n-alkyl-PEO with a molecular weight of roughly 5kg/mol. In water these molecules form star-like micelles with a strongly segregated alkane core that partially crystallizes. This creates an additional energy barrier that needs to be overcome during chain expulsion. We employ time-resolved small-angle neutron scattering (TR-SANS) to track the exchange kinetics. We investigated mixtures of C28-PEO and C22-PEO and determined the respective melting enthalpies using differential scanning calorimetry (DSC) which was quantitatively compared to the kinetic data obtained from TR-SANS. We found that the core crystallization occurs cooperatively while the intermicellar chain exchange processes of C28-PEO and C22-PEO are virtually decoupled.