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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: POSTER: Polymer Physics

CPP 8.17: Poster

Montag, 26. März 2007, 16:00–18:00, Poster B

Fluctuation Effects in the Theory of Microphase Separation in Diblock Copolymers in the Presence of an Electric Field — •Ilja Gunkel, Semjon Stepanow, Thomas Thurn-Albrecht, and Steffen Trimper — Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle

We generalize the Fredrickson-Helfand theory of the microphase separation in symmetric diblock copolymer melts by taking into account the influence of a time-independent homogeneous electric field on the composition fluctuations within the self-consistent Hartree approximation. We predict that electric fields suppress composition fluctuations, and consequently weaken the first-order transition. In the presence of an electric field the critical temperature of the order-disorder transition is shifted towards its mean-field value.

We also compute the collective structure factor in the disordered phase, which becomes anisotropic in the presence of the electric field. Fluctuational modulations of the order parameter along the field direction are suppressed. The latter correlates with the parallel orientation of the lamellae in the ordered state.