Regensburg 2010 – wissenschaftliches Programm

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SYMR: Symposium Nuclear Magnetic Resonance: from Applications in Condensed-Matter Physics to New Frontiers

SYMR 2: Poster: Nuclear Magnetic Resonance - Frontiers and Applications

SYMR 2.8: Poster

Montag, 22. März 2010, 16:30–18:00, Poster C

Miniemulsion Polymerization Reactions Observed by Time-Resolved Xe-129 NMRR — •Mathis Düwel, Nicolas Vogel, Clemens Weiss, Katharina Landfester, Hans W. Spiess und Kerstin Münnemann — Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

In the last years, Xe-129 NMR has found many applications in material science and medicine because of two useful properties of Xenon atoms in NMR: their sensitivity to their environment due to their highly polarizable electron cloud, even without the need for covalent bonds, and the ability of being hyperpolarized. Here, Xe-129 NMR is used in the online monitoring of polymerization reactions. The method allows for the online monitoring of polymerization by reporting quantitatively the composition of the reaction mixture by the chemical shift of hyperpolarized Xe. The hyperpolarized gas is brought into contact with the reaction mixture in an NMR tube in a 7 T-NMR spectrometer by the use of hydrophobic hollow-fibre membranes, allowing for the molecular dissolution of the hyperpolarized Xe into the miniemulsion. Repeated Xe-129 NMR measurements show the time-resolved polymerization process. The depolarized Xe is continuously replaced by the gas flow from the hyperpolarizer. Kinetic data for different reaction conditions (e.g., different initiators) has been determined from the chemical shift of the dissolved Xenon, allowing for the comparison with calorimetric data.