BPCPPDYSOE21 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
DY: Fachverband Dynamik und Statistische Physik
DY 17: Complex Fluids - organized by Christine M. Papadakis (Technical University of Munich, Garching) (joint session CPP/DY)
DY 17.1: Hauptvortrag
Dienstag, 23. März 2021, 09:00–09:40, CPPb
Polymer Micelles with Crystalline Cores: confinement effects, molecular exchange kinetics and mechanical response — Nico Koenig1, Lutz Willner2, and •Reidar Lund1 — 1Department of Chemistry, University of Oslo, Postboks 1033 Blindern, 0315 Oslo, Norway. — 2Jülich Centre for Neutron Science JCNS and Institute for Complex Systems ICS,
Partially crystalline, self-assembling systems with multiple components are omnipresent in nature with living cells as a prominent example. Here we study micelles formed by self-assembly of a series of well-defined n-alkyl-(polyethylene oxide) (Cn-PEO) polymers in aqueous solutions [1]. Using small-angle X-ray/neutron scattering (SAXS/SANS), densiometry and differential scanning calorimetry (DSC), we show that the n-alkane exhibit a first-order phase transition in the micellar cores, but with reduced melting points accurately described by the Gibbs-Thomson equation [2]. The effect of core crystallinity on the molecular exchange kinetics is investigated using time-resolved SANS (TR-SANS) [3-9]. We show that the melting transition is cooperative in the confined micellar core, whereas the exchange process is decoupled and unimeric in nature. [9] Telechelic polymers based on Cn-PEO-Cn forms clustered micelles and hydrogels composed of interconnected micelles at higher concentrations.[10] The results show that, contrary to regular micelles, the kinetics occurs in a multistep process involving a novel collision-induced single-molecule exchange mechanism.[11] Morever exchange kinetics directly controls the mechanical response of hydrogels through the bond life time [12]