Regensburg 2007 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 7: POSTER: INTERNAL SYMPOSIUM Scattering Experiments
CPP 7.1: Poster
Montag, 26. März 2007, 16:00–18:00, Poster B
Electric field effects on alignment of lamellar structures in diblock copolymer thin films studied by neutron scattering — •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
Self-assembled block copolymers have attracted much attention in recent years for their potential use as nanostructure templates. In this context, it is of interest to control the order and orientation of block copolymer thin films by means of external electric fields. In order to gain additional understanding of the alignment process, we studied the effect of a weak electric field on a lamellar microphase structure oriented perpendicular to the electric field by neutron diffuse scattering in reflection geometry. It has been predicted that the electric field induces periodic structural undulations which lead to a disruption of the original structure and facilitate reorientation to set in. In our experiments on lamellar PS-PMMA block copolymers these field-induced undulations were not observed. Rather, already after preparation the films displayed a diffuse intensity interpreted as corresponding to a mosaic structure of domains with a typical correlation length of about 1-2 µm. This diffuse intensity increases after the application of the field, even if the field is too weak to induce alignment. The lateral length scale of the mosaicity remains unaffected by the electric field.