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PO: Polymerphysik

PO 9: Poster: Copolymere und Polymermischungen

PO 9.8: Poster

Monday, March 17, 1997, 15:30–17:30, Gg

Junction Point Fluctuations in Ordered Poly(styrene)-Poly(isoprene)-Poly(styrene) Triblock Copolymers — •I. Alig¹, G. Floudas², A. Avgeropoulos³, and N. Hadjichristidis³ — ¹Deutsches Kunststoff-Institut, Schloßgartenstr. 6, D-64289 Darmstadt, Germany — ²Foundation for Research and Technology-Hellas (FORTH), P.O. Box 1527, 711 10 Heraklion, Crete, Greece — ³Dept. of Chemistry, University of Athens and FORTH

We report on the local and global dynamics of bulk PS-PI-PS triblock copolymers in the lamellar phase using dielectric spectroscopy and rheology. There are four dielectrically active processes in the triblock copolymers which starting from low temperatures, reflect: (i) the PI segmental dynamics, (ii) a suppressed, but yet measurable PI normal mode-like process associated with the junction point fluctuations at the interface, (iii) the PS-like segmental relaxation and (iv) a slower mode associated with the reorientation of the interface. From the dielectric strength of the second process an estimate of the mean-square fluctuations of the junction points is given (about 2-5nm) which is in good agreement with independent calculations of the interfacial width. Dielectric spectroscopy can, therefore, effectively be used as a dynamic probe of the interface in ordered triblock copolymers. Rheology provides a broad spectrum of modes reflecting the PI and PS local segmental dynamics, the dynamics of entangled PI chains and slower modes associated with the interface.