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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 13: Poster: Crystallization and Self Assembly
CPP 13.8: Poster
Monday, March 22, 2010, 16:30–18:00, Poster C
Influence of Electric Fields on the Phase Behavior of Concentrated Block Copolymer Solutions — •Heiko G. Schoberth1,2, Christian W. Pester1, Kristin Schmidt3, Kerstin A. Schindler1,2, and Alexander Böker1 — 1Lehrstuhl für Makromolekulare Materialien und Oberflächen and DWI an der RWTH Aachen e.V., RWTH Aachen University, 52056 Aachen, Germany — 2Lehrstuhl für Physikalische Chemie II, Universität Bayreuth, 95440 Bayreuth, Germany — 3Materials Research Laboratory, University of California, Santa Barbara, USA
We investigate the influence of the electric field on the phase behavior of diblock copolymers in concentrated solutions using synchrotron small-angle X-ray scattering (synchrotron SAXS). When heating the solutions through the order-disorder transition temperature TODT, we find a significant decrease in TODT with increasing electric-field strength. In addition we found a temperature regime in which it is possible to switch between the disordered and phase separated state at constant temperature upon application of a moderate electric field.
Furthermore we can also induce an order-order-transition. We synthesized different block copolymers with compositions close to the predicted phase boundaries. Due to the lower free energy of aligned anisotropic microdomain structures parallel to the electric field, we can induce a transition from the metastable hexagonally perforated lamellae to the lamellae phase under strong electric fields. In addition for an isotropic cubic gyroid phase, which cannot be aligned, a transition to aligned cylinders is found.