  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.
