Dresden 2009 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 13: POSTERS Polymer Physics
CPP 13.17: Poster
Tuesday, March 24, 2009, 14:00–16:30, P3
Polymer blends and diblock copolymer melts in external electric fields — •Ilja Gunkel1 and Semjon Stepanow2 — 1Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany — 2Martin-Luther-Universität Halle-Wittenberg, Institut für Physik, 06099 Halle, Germany
We generalize the statistical mechanical description of low molecular liquid systems in external electric fields in the E-ensemble at constant potential [1] to polymer blends and diblock copolymer melts. The anisotropic part of the segment polarizability results in a change of the polymer shape from a Gaussian coil to an ellipsoid. The effective binary interactions between the segments, which we have calculated to the quadratic order in the segment polarizabilities, are attractive in the ensemble at fixed potential, and result in an upward shift of the critical temperature in phase transitions in these systems. We have generalized the Flory-Huggins free energy for polymer blends in an electric field in both the E- and the E0-ensembles (constant charges). The collective structure factor for diblock copolymer melts is computed by taking into account the anisotropic parts of the segment polarizabilities as well as the effective binary interactions. We also computed the dielectric permittivity of the diblock copolymer melt in the vicinity of the order-disorder transition. The results of the statistical mechanical treatment of diblock copolymer melts are compared with the existing phenomenological approaches for these systems.
[1] S. Stepanow and T. Thurn-Albrecht, submitted, preprint http://arxiv.org/abs/0810.1881