Regensburg 2010 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 34: Poster: Elastomers and Gels
CPP 34.5: Poster
Mittwoch, 24. März 2010, 17:30–19:00, Poster C
Electromechanical properties and structural changes of smectic C* liquid crystal elastomers under shear — •Periklis Papadopoulos1, Patrick Heinze2, Wilhelm Kossack1, Friedrich Kremer1, and Heino Finkelmann2 — 1Universität Leipzig, Institut für Experimentelle Physik I — 2Albert-Ludwigs-Universität Freiburg, Institut für Makromolekulare Chemie
Liquid crystal elastomers combine the electrical and optical properties of liquid crystals with the mechanical ones of polymer networks. In smectic C systems, doping with chiral mesogen induces the formation of domains with permanent electric dipole moment, which exhibit piezoelectric properties. During the simultaneous crosslinking and orientation of the mesogen in a magnetic field a polydomain morphology is obtained, where the piezoelectric effects are averaged out on a macroscopic length scale. The application of shear breaks the symmetry and induces the formation of monodomain structure. In this study the structural changes during stepwise shear are compared with the measurements of the direct piezoelectric effect. It is shown that the piezoelectric coefficient reaches its maximum at a certain shear angle that corresponds to the completion of polydomain to monodomain transformation. The complex coefficient shows a strong dependence on temperature, especially near the smectic to isotropic transition, but also on the static mechanical stress and frequency. The effects are discussed with respect to system non-linearity.