Metastable Untwisted States in Cholesteric Elastomers

Abstract

The formation of untwisted states of cholesteric elastomers was forced by cooling from the isotropic to the liquid crystalline phase in the presence of mechanical strain. Evidence of the structural changes were provided by comparison of transmission spectra for polarized light with spectra calculated according to theory. At released strain, the states were found to have long lifetimes and to be metastable with respect to twisted states. Large energy barriers for the nucleation of disclinations, necessary for direct transitions between untwisted and twisted states, have to be considered.