Dresden 2006 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 13: POSTER New Experimental Techniques
CPP 13.14: Poster
Tuesday, March 28, 2006, 17:00–19:00, P3
In situ study on the mechanisms of living polymerization via small angle neutron scattering and 1H NMR — •Aizhen Niu1, Joerg Stellbrink1, Juergen Allgaier1, Lutz willner1, Dieter Richter1, Bernd W. Koenig2, Roland P. May3, and L. J. Fetters4 — 1Institute fur Festkorperforschng, Forschungszentrum, Jülich GmbH, 52425 Jülich, Germany — 2IBI-2, Forschungszentrum, Jülich GmbH, 52425 Jülich, Germany — 3Institute Lau-Langevin, F-38042, Grenoble, Cedex 9, France — 4School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14583-5201
In this work for the first time a combined 1H-NMR and small angle neutron scattering in situ study of the anionic polymerization was performed. Both initiation and propagation phases were explored. This combined technique allows the structural and kinetic characteristics to be accessed and cross compared. The smaller aggregates contain most of the reacted monomer. Their structure changes from high functionality wormlike chains at early stages of the reaction to star-like aggregates where the crossover occurs at a degree of polymerization of 40. It is clear that the measurement of kinetic orders is not a tool that can be used to assay aggregation states as has long been assumed. The period when initiation and propagation occurred simultaneously was found to consist of three regimes where the initiation rate increased with time, the aggregation states of the living chains are decreasing with increasing rate.