Münster 1999 – wissenschaftliches Programm

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CP: Chemische Physik

CP 24: Dynamik molekularer Systeme

CP 24.5: Vortrag

Donnerstag, 25. März 1999, 12:15–12:30, Phy

Effect of Chemical Constraints on Chain Dynamics in Polybutadiene Containing Blockcopolymers as Observed by Double Quantum NMR Spectroscopy — •Thilo Dollase, Robert Graf, Andreas Heuer, and H.W. Spiess — Max-Planck-Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz

Recently, high resolution double quantum NMR spectroscopy on protons in the solid state has been applied to reveal main chain ordering and dynamics in polybutadiene (PB) [1]. >From these experiments dynamic order parameters have been determined. Resulting data has successfully been attributed to the reptation model of polymer motion. Extending these studies, we present results obtained for diblock copolymers that contain PB with either one or two chemically fixed chain ends. For this purpose we analyzed poly(styrene-b-butadiene) (PS-b-PB) and end-capped zwitterionic +PS-b-PB- [2] at temperatures below the glass transition of the PS block. PS-b-PB represents a class of systems incorporating one fixed chain end whereas the zwitterionic species serves as a model system with both PB chain ends fixed. PS-b-PB of variable chain lengths has been investigated in order to elucidate not only the influence of the fixing points but also of entanglements on chain dynamics in the PB melt.

[1] R. Graf, A. Heuer, H. W. Spiess, Phys. Rev. Lett., 1998, 80, 5738

[2] V. Schädler, J. Spickermann, H.-J. Räder, U. Wiesner, Macromolecules, 1996, 29, 4685