On the molecular origins of the ferroelectric splay nematic phase

TL;DR

This paper investigates the molecular mechanisms behind the formation of the ferroelectric splay nematic phase, highlighting how subtle molecular changes influence polar ordering and demonstrating the potential of molecular dynamics simulations for designing such materials.

Contribution

It reveals that small molecular structural modifications can promote polar nematic phases by enabling denser packing, and advocates for molecular dynamics simulations as a tool for material design.

Findings

Subtle molecular structure changes enable denser packing in polar nematic phases.

Reduction of excluded volume is key to the formation of the ferroelectric splay nematic phase.

Molecular dynamics simulations are effective for designing polar nematic materials.

Abstract

Nematic liquid crystals have been known for more than a century, but it was not until the 60s-70s that, with the development of room temperature nematics, they became widely used in applications. Polar nematic phases have been long-time predicted, but have only been experimentally realized recently. Synthesis of materials with nematic polar ordering at room temperature is certainly challenging and requires a deep understanding of its formation mechanisms, presently lacking. Here, we compare two materials of similar chemical structure and demonstrate that just a subtle change in the molecular structure enables denser packing of the molecules when they exhibit polar order, which shows that reduction of excluded volume is in the origin of the polar nematic phase. Additionally, we propose that molecular dynamics simulations are potent tools for molecular design in order to predict, identify and design materials showing the polar nematic phase and its precursor nematic phases.