Regensburg 2007 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 7: POSTER: INTERNAL SYMPOSIUM Scattering Experiments

CPP 7.20: Poster

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

Scaling behavior of the reorientation kinetics and changes in the phase behavior of block copolymers exposed to electric fields — •Heiko G. Schoberth¹, Kristin Schmidt¹, Thomas M. Weiss², Agur Sevink³, Andrei V. Zvelindovsky⁴, Alexander Böker¹, and Georg Krausch¹ — ¹Lehrstuhl für Physikalische Chemie II, Universität Bayreuth, D-95440 Bayreuth, Germany — ²European Synchrotron Radiation Facility (ESRF), F-38043 Grenoble, France — ³Leiden Institute of Chemistry, Universiteit Leiden, The Netherlands — ⁴Department of Physics, Astronomy & Mathematics, University of Central Lancashire, Preston PR1 2HE, United Kingdom

We have followed the reorientation kinetics of various block copolymer solutions exposed to an external electric DC field by time-resolved synchrotron small-angle X-ray scattering (SAXS). The characteristic time constants follow a power law indicating that the reorientation is driven by a decrease in electrostatic energy. Moreover, the observed exponent suggests an activated process in line with the expectations for a nucleation and growth process. When properly scaled, the data collapse onto a single master curve spanning several orders of magnitude both in reduced time and in reduced energy. The power law dependence of the rate of reorientation derived from computer simulations based on dynamic density functional theory (MesoDyn) agrees well with the experimental observations. In addition, we observe an influence of the electric field on the order disorder temperature and phase separation in our block copolymer solutions. For further investigations we study this effect by birefringence and SAXS.