Understanding Atomic-Scale Behavior of Liquid Crystals at Aqueous Interfaces

Area of Science:

• Materials Science
• Physical Chemistry
• Computational Chemistry

Background:

• Liquid crystals (LCs) offer unique interfacial properties for advanced applications like biosensors.
• Understanding LC-water and LC-air interfaces is crucial but limited.
• Molecular events at LC interfaces propagate over long distances.

Purpose of the Study:

• Investigate the molecular organization of 4-cyano-4'-pentylbiphenyl (5CB) at vacuum and aqueous interfaces.
• Examine how hybrid interfaces influence 5CB structure and ordering.
• Clarify the role of the nitrile group in interfacial interactions.

Main Methods:

• Large-scale atomistic molecular dynamics (MD) simulations.
• Hybrid boundary conditions simulating confinement between vacuum and water.
• 2D potential of mean force (PMF) calculations and polarization density analysis.

Main Results:

• 5CB demonstrated homeotropic anchoring at vacuum interfaces and planar alignment at aqueous interfaces.
• The polar nitrile group of 5CB remained hydrated, influencing water molecule orientation.
• Anchoring strength showed oscillatory decay at vacuum and semilinear decay at aqueous interfaces.

Conclusions:

• Simulations accurately predict 5CB interfacial behavior, consistent with experimental observations.
• The study provides fundamental insights into LC-fluid interactions at interfaces.
• Findings advance the design of LC-based devices utilizing interfacial phenomena.