Since being experimentally discovered in 2017 the ferroelectric nematic phase has proven to be the hottest topic in the field of liquid crystals because of its real application potential. This review summarises the compounds which exhibit this fascinating phase and describes the structural differences between them from a chemist's perspective.

Abstract

The discovery of a new polar nematic phase; the ferroelectric nematic, has generated a great deal of excitement in the field of liquid crystals. To date there have been around 150 materials reported exhibiting the ferroelectric nematic phase, in general, following three key archetypal structures with these compounds known as RM734, DIO and UUQU-4N. In this review, the relationship between the molecular structure and the stability of the ferroelectric nematic, N_F, phase will be described from a chemist's perspective. This will look to highlight the wide variety of functionalities which have been incorporated into these archetypal structures and how these changes influence the transition temperatures of the mesophases present. The N_F phase appears to be stabilised particularly by reducing the length of terminal alkyl chains present and adding fluorines laterally along the length of the molecular backbone. This review will look to introduce the background of the ferroelectric nematic phase before then showing the molecular structures of a range of materials which exhibit the phase, describing their structure–property relationships and therefore giving an up–to–date account of the literature for this fascinating new mesophase.