Dresden 2006 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 12: POSTER Colloids, Nanoparticles and Self-Organizing Systems
CPP 12.13: Poster
Dienstag, 28. März 2006, 17:00–19:00, P3
Electric fields effects in thin films of symmetric diblock copolymers — •Xiuli Jiang1, Thomas Gutberlet2, Mukul Gupta2, Thomas Geue2, and Thomas Thurn-Albrecht1 — 1Department of Physics, Martin-Luther-University, Halle, Germany — 2Laboratory for Neutron Scattering, ETH Zürich & PSI, Villigen, Switzerland
Due to their potential use as nanostructure templates, it is of significant interest to control the orientation and order of the microstructure of block copolymers by means of external fields. Using neutron reflectivity, diffuse scattering and small angle scattering we analysed the microstructure of a lamellar diblock copolymer under competing influences of interfacial interactions and an electric field standing perpendicular to the surface of the film. While the electric field tends to align the lamellar normal to the substrate, interfacial interactions favour an alignment parallel to the film. In this situation a field, too weak to overcome the interfacial interactions which is typically limited to a range of about lamellar periods, leads to a reduction of the defects at the boundaries between domains of different orientations, and in consequence to a complete alignment of the microphase structure parallel to the substrate. Otherwise, due to the confinement the torque exerted by the electric field leads only to a small increase of the mosaicity of the sample, which is reflected by a considerable increase in the diffuse scattering signal. Finally a field of several ten kV/mm is necessary to align the central part of the film with boundary layers parallel to the interfaces remaining even at these high fields.