Macromolecules39, 8163 (2006)

Variation of the Network Anisotropy of Cholesteric Side Chain Elastomers

Christian Bourgerette1, Bin Chen2, Heino Finkelmann2, Michel Mitov1, Jürgen Schmidtke3, Werner Stille3

1Centre d'Elaboration de Matériaux et d'Etudes Structurales, CNRS, BP 94347, 31055 Toulouse Cedex 4, France

2Institut für Makromolekulare Chemie, Albert-Ludwigs-Universität, Stefan-Meier-Str. 31, 79104 Freiburg, Germany

3Physikalisches Institut, Albert-Ludwigs-Universität, Hermann-Herder-Str. 3, 79104 Freiburg, Germany


A series of cholesteric side chain elastomers with odd and even numbers of atoms along the spacer chain was prepared. Varying the content of odd and even spacer groups resulted in anisotropic main chain conformations changing from prolate to oblate. The conformation anisotropy was characterized by temperature dependent measurements of the sample dimensions. The transmission spectra for polarized light of the elastomer films were recorded under uniaxial mechanical stress, applied perpendicular to the helical axis of the cholesteric liquid crystal. With increasing strain a blue shift of the selective reflection due to a contraction of the helix along its axis was observed. In the case of a non-vanishing conformation anisotropy in addition a distortion of the regular helical structure was indicated by changes in the transmission spectra for linearly polarized light. This distortion was found to be much weaker than predicted by theory.