An Atomic-Scale Investigation of Liquid Crystal Orientation in Polar and Nonpolar Solvents.

Liquid crystals (LCs) exhibit unique ordered environments at interfaces, enabling functionalities in optical devices and biosensors. Their ability to transmit molecular interactions over macroscopic distances is well-known, yet the atomic-scale behavior of LC interfaces with polar and nonpolar solvents remains unclear. This study employs atomistic molecular dynamics (MD) simulations to investigate the orientation and structure of 4-cyano-4'-pentylbiphenyl (5CB) in vacuum, water, ethanol, and methane. Polar solvents promote the smectic phase but disrupt the molecular organization at interfaces through strong interactions with the nitrile group. Tilting of the 5CB molecules can be explained by density distributions and order parameters. In contrast, nonpolar solvents such as methane preserve the native ordering of 5CB, resulting in compact and parallel molecular arrangements with an increase in structural stability. These insights into solvent-induced structural stability and molecular orientation are crucial for optimizing liquid-crystal-based technologies.