Nuclear magnetic resonance of pretransitional ordering of liquid crystals in well defined nano-geometries: the utility of the Landau–de Gennes formalism

Abstract

The Landau–de Gennes (LdG) formalism has had a significant impact in many areas of physics and perhaps arguably most of all in understanding liquid crystals. In this review, we treat the utility of the LdG formalism in studying the ordering of liquid crystal systems confined at the nanoscale. The LdG formalism describes surface-induced ordering phenomena above the second-order phase transition point and predicts the disappearance of the nematic–isotropic transition into a continual evolution of order under certain conditions. We focus this paper on how the LdG theory has been used to understand ordering in well-defined nanoscaled environments, such as cylinders and ellipsoidal droplets, using deuterium nuclear magnetic resonance (²H-NMR) to probe the evolution of order as it develops above the isotropic–nematic transitions and through the transition itself.

Keywords:

• liquid crystals
• nano-confined geometries
• paranematic phase
• surface-induced ordering
• polymer-dispersed liquid crystals
• nanoporous alumina membrane