Phase chirality and stereo-selective swelling of cholesteric elastomers
Cavendish Laboratory, University of Cambridge, Madingley Road, CB3 0HE, Cambridge, UK
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Cholesteric elastomers possess a macroscopic “phase chirality” as the director rotates in a helical fashion along an optical axis z and can be described by a chiral order parameter . This parameter can be tuned by changing the helix pitch p and the elastic properties of the network at formation. The cholesterics also possess a local nematic order, changing with temperature or during solvent swelling. In this paper, by measuring the power of optical rotation , we discover how these two parameters vary as functions of temperature or solvent adsorbed by the network. The main result is a finding of pronounced stereo-selectivity of cholesteric elastomers, demonstrating itself in the retention of the “correct” chirality component of a racemic solvent. It has been possible to quantify the amount of such stereo-separation, and the basic dynamics of the effect.
© EDP Sciences, Società Italiana di Fisica, and Springer-Verlag, 2003