Molecular complexity and the control of self-organising processes

Abstract

In this article we investigate the complexity of the molecular architectures of liquid crystals based on rod-like mesogens. Starting from simple monomeric systems founded on fluoroterphenyls, we first examine the effects of aromatic core structure on mesophase formation from the viewpoint of allowable polar interactions, and then we model these interactions as a function of terminal aliphatic chain length. By incorporating a functional group at the end of one, or both, of the aliphatic chains we study the effects caused by intermolecular interfacial interactions in lamellar phases, and in particular the formation of synclinic or anticlinic modifications. We then develop these ideas with respect to dimers, trimers, tetramers, etc. We show, for dendritic systems, that at a certain level of molecular complexity the local mesogenic interactions become irrelevant, and it is gross molecular shape that determines mesophase stability. The outcome of these studies is to link the complexity of the molecular interactions at the nanoscale level, which lead to the creation of the various liquid-crystalline polymorphs, with the formation of mesophases that are dependent on complex shape dependencies for mesoscopic supermolecular architectures.

Keywords:

• liquid crystal polymorphs
• liquid crystal modelling
• ferroelectric and antiferroelectric liquid crystals
• dimers
• trimers and tetramers
• polymer liquid crystals
• dendrimers
• supermolecular liquid crystals

Acknowledgements

We would like to thank the Leverhulme Trust, the Department of Trade and Industry, the Royal Society, the European Science Foundation, the University of Hull, Kingston Chemicals Ltd, Merck UK, Defence and Research Agency (DERA) and the Engineering and Physical Sciences Research Council (EPSRC) for financial support.