Understanding the unusual transitional behaviour of liquid crystal dimers

The transitional properties of liquid crystal dimers within a homologous series differ significantly depending on whether the spacer joining the two mesogenic groups contains an even or an odd number of atoms. In order to obtain a physical understanding of this unusual behaviour we have developed a simple model in which the component molecules can adopt just two conformations, one linear and the other bent. An analysis of the model within the molecular field approximation reveals that it is able to provide us with a good understanding of the behaviour of liquid crystal dimers. In addition it predicts the existence of a nematic-nematic transition.