Column undulation instability in a discotic liquid crystal

Abstract

We present the first observation of an undulation instability of the columns in a tubular discotic liquid crystal when submitted to a dilation normal to the columns. This effect is very similar to the layer undulation in smectic materials. From the instability threshold and from the undulation wavelength, we derive a value, anomalously large, of the column curvature elastic constant, very close to the value obtained from observation of the column buckling under longitudinal compression. The static or dynamic origin of such a large curvature elastic constant is not understood Presentation de la premiere observation d'une instabilite d'ondulation des colonnes dans un cristal discotique tubulaire lorsqu'il est soumis a une dilatation normale aux colonnes. Deduction d'une valeur anormalement elevee de la constante elastique de courbure des colonnes a partir du seuil d'instabilite et de la longueur d'onde des ondulations