Dresden 2006 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 27: POSTER Polymer Physics and Materials
CPP 27.22: Poster
Donnerstag, 30. März 2006, 17:00–19:00, P2
Manipulation of the smectic layer spacing in liquid crystal elastomer films by mechanical stress — •Victor Aksenov1, Jürgen Bläsing1, Ralf Stannarius1, Martin Rössle2, and Rudolf Zentel2 — 1Otto-von-Guericke-Universität Magdeburg, Inst. für Experimentalphysik — 2Johannes-Gutenberg-Universität Mainz, Inst. für Organische Chemie
Liquid crystal elastomers (LCEs) are rubbers with anisotropic elastic moduli. For deformations in the plane of smectic layers, they behave like two-dimensional isotropic rubbers, with elastic moduli close to those of conventional rubber materials. For deformations perpendicular to the layers, the elastic moduli can be two orders of magnitude higher than for conventional rubbers, comparable to the smectic layer compression modulus. It was observed earlier that deformations of SmA LCE parallel to the smectic layers do not change the sample thickness, this corresponds to a Poisson ratio close to 1 parallel to smectic layers, and zero perpendicular to it [1]. In our material, the measured Poisson ratio is close to 1/2. Simultaneous optical reflectometry and small angle X-ray scattering reveal that in-plane deformations of the LCE sample cause changes of the smectic layer spacing [2]. SmA and SmC* phases show similar elastic behaviour, comparable to isotropic rubber. A layer compression up to 30 % was achieved mechanically. Such an effect has been observed for the first time in smectic LCE.
[1] E. Nishikawa and H. Finkelmann, Macromol. Chem. Phys. 200, 312 (1999). [2] V. Aksenov et al., Liq. Cryst. 32, 805 (2005).