Berlin 2005 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 5: SYMPOSIUM: Dynamics of multi-component fluids POSTER
CPP 5.28: Poster
Freitag, 4. März 2005, 17:15–19:00, Poster TU D
Electric field induced structural deformations in lamellar block copolymers — •X. Jiang1, T. Thurn-Albrecht1, T. Gutberlet2, and M. Gupta2 — 1Department of Physics, Martin-Luther-University Halle-Wittenberg, 06120 Halle, Germany — 2Laboratory for Neutron Scattering, ETHZ&PSI, CH-5232 Villigen PSI, Switzerland
Phase separation in block copolymers is restricted to molecular length scales, as a result self-assembled nanoscopic structures of different symmetries are formed in these materials. For thin films electric fields turned out to be an especially effective tool to control the orientation and order of these materials, though the details of the alignment process are not yet completely understood.
Using the time-of-flight (TOF) mode on the AMOR neutron reflectometer at the Paul-Scherrer-Institute, we studied the influence of an electric field on poly(styrene-block-methylmethacrylate) with a lamellar microstructure misaligned with respect to the electric field, in the specular and off-specular scattering regions. Even in films aligned parallel to the substrate thermally excited structural fluctuations - undulations with small amplitudes exist. A weak electric field leads to a more perfect alignment of the lamellae perpendicular to the field, which we understand as a consequence of defect suppression by the field. In addition the amplitude of the above mentioned undulations is increased by effect of the field. As expected this effect can eventually lead to a disruption and a partial alignment of the lamellar structure.