Dresden 2003 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 20: POSTER A

CPP 20.11: Poster

Montag, 24. März 2003, 19:00–21:00, ZEU/250

Orientation of the Crystalline-Amorphous Superstructure of Poly(ethylene oxide) in a Strong Magnetic Field — •Tsvetelina Grigorova¹, Thomas Thurn-Albrecht¹, Sterios Pispas², and Nikos Hadjichristidis² — ¹Fakultät für Physik, Universität Freiburg, 79104 Freiburg, Germany — ²Department of Chemistry, University of Athens, 15784 Ilissia, Greece

For several semicrystalline polymers it has been shown that crystallization in a strong magnetic field leads to the formation of an oriented texture. Orientation is caused by the diamagnetic anisotropy of the crystallites in the sample. While the parameters controlling the extent of orientation have been identified in several cases, the exact mechanism leading to orientation is not completely understood. We present a study of magnetic field induced orientation in polyethyleneoxide, a polymer which was not studied in this context so far. This polymer offers the possibility to extend our study to semicrystalline block copolymers. X-ray scattering was used to analyze the orientation of the samples.

In agreement with results obtained previously for isotactic polystyrene, we find that the degree of orientation achieved by crystallization in a magnetic field is controlled by the temperature of crystallization T_c and a second temperature T_max, the maximum temperature to which the sample was heated during the melting process prior to crystallization. The temperature T_max also controls the number of nuclei via self seeding. Macroscopic orientation results only from crystallization starting from a high number of nuclei. Initial results from oriented crystallization of block copolymers will be also presented.