Insertion of liquid crystal molecules into hydrocarbon monolayers

Abstract

Atomistic molecular dynamics simulations were carried out to investigate the molecular mechanisms of vertical surface alignment of liquid crystals. We study the insertion of nCB (4-Cyano-4'-n-biphenyl) molecules with n = 0,…,6 into a bent-core liquid crystal monolayer that was recently found to provide good vertical alignment for liquid crystals. The results suggest a complex-free energy landscape for the liquid crystal within the layer. The preferred insertion direction of the nCB molecules (core or tail first) varies with n, which can be explained by entropic considerations. The role of the dipole moments was found to be negligible. As vertical alignment is the leading form of present day liquid crystal displays (LCD), these results will help guide improvement of the LCD technology, as well as lend insight into the more general problem of insertion of biological and other molecules into lipid and surfactant layers.

Designing Biological Microsensors with Chiral Nematic Liquid Crystal Droplets

“…This was additionally demonstrated for nonchiral materials, such as the surfactants and fatty acids we use in this work, where the final equilibrium pitch of the fingerprint texture differs from the measured pitch using a chiral dopant alone: in their work, by using a long-pitch CLC, the fingerprint spacing when using air as the homeotropic anchoring substrate differed from when a nonchiral surfactant (such as SDS and tetraethylene glycol monooctyl ether, a nonionic surfactant) was used to induce homeotropic anchoring . While their work was typically performed with amphiphile concentrations well above the CMC, it gives us a clue that one of the main determining factors is the interaction of the tails with the LC changing the twisting of the CLC due to the insertion of the hydrocarbon tails into the LC material: , since our LC materials are effectively oils, the hydrocarbon tails will preferentially insert themselves into the oil phase to minimize energy. We would expect that identical tails should produce similar distortions in the LC interface, part of the reason we chose to study lauric acid and SDS, but we found this not to be the case.…”

Thermotropic Liquid Crystal-Assisted Chemical and Biological Sensors

“…Recently, complete fully atomistic models of capsids such as of HIV-1 and Hepatitis-B viruses were developed [ 134 , 135 , 136 ], which may facilitate much more accurate modeling of interaction events at biosensor/capsid interfaces. MD simulations were also employed in revealing the details of the organization of LC molecules in thin films at interfaces [ 137 , 138 , 139 ] (See Figure 24 ) and were used in predicting their stability and rupture mechanisms [ 140 ]. When simulations results agree well with real experimental observations, the MD serves as a “computational microscope” [ 141 ] that allows visualization of objects that often no other tool can.…”

Determination of Concentrations of Surface-Active Materials in Aqueous Solutions at Different pH Values Using Liquid Crystals

“…It is possible, that in our case the aliphatic chains of the surfactant molecules penetrate [13,14] into the LC at the LC/water interface as depicted in Fig. 10.…”