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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 42: Polymer Physics IV

CPP 42.8: Vortrag

Freitag, 27. März 2009, 12:15–12:30, ZEU 160

Chain conformations in bidisperse blends of linear chains — •Michael Lang and Jens-Uwe Sommer — Leibniz Institut für Polymerforschung Dresden

Bidisperse polymer melts containing a small fraction of N-mers in a matrix of P-mers were studied using the bond fluctuation model. For mono-disperse melts (N=P) we find deviations from ideal chain conformations in melt similar to previous studies [e.g. J.P. Wittmer, P. Beckrich, H. Meyer, A. Cavallo, A. Johner, J. Baschnagel, PhysRevE 76, 011803 (2007)] including long range correlations of bond vector orientations. The excluded volume screening in a dense melt according to the random phase approximation is controlled by the scaling variable N^1/2/P. For the case N^1/2>P, the N-mers should follow again the excluded volume statistics and the ratio R²/N (R-extension of the N-mers) should scale as (P²/N)^α with α ≈ 1−2ν≈−0.176. Similar to experimental studies [Landry, Macromolecules 30, 7500 (1997)] we find an effective α ≈ −0.09 ± 0.01. Possible reasons for the observed deviation to the theoretical prediction are discussed.