Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 34: POSTERS Polymerphysics
CPP 34.35: Poster
Donnerstag, 28. Februar 2008, 17:00–19:30, Poster A
Are there cross-aggregates? In-situ NMR study of the t-butyllithium initiated butadiene polymerization — •Aizhen Niu1, J. Allgaier1, L. Willner1, J. Stellbrink1, D. Richter1, R. Hartmann2, and L. J. Fetters3 — 1IFF, Forschungszentrum Jülich, D-52425 Jülich — 2INB2, Forschungszentrum Jülich, D-52425 Jülich — 3Cornell University, Ithaca, NY 14853, USA
The anionic polymerization kinetics and mechanism are complicated by the aggregation phenomena of organolithium compounds. In our previous work, the kinetics and aggregation states were investigated under standard polymerization conditions by the combination of in situ small angle neutron scattering (SANS) and 1H NMR techniques. 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. We found that the existence of cross-aggregates formed from initiator and the polybutadienyllithium head groups can be the reason making the initiator become more reactive than in the pure self-aggregated state. In an attempt to understand the influence of cross-aggregattion plays in anionic polymerization, the investigation on cross-aggregation of an anionic polymerization were performed by high resolution 1H NMR and Li7 NMR. The cross-aggregation in the mixture of t-butyllithium and living chains, 3-Neopentylallyllithium and in the initiation stage of real polymerization were studied. It is clear that there are cross-aggregates and they play an important role in anionic polymerization.