Chirality Detection Using Nematic Liquid Crystal Droplets on Anisotropic Surfaces

Rudquist, Per; Dietrich, Clarissa F.; Mark, Andrew; Gießelmann, Frank

doi:10.1021/acs.langmuir.6b00382

Cited by 4 publications

(3 citation statements)

References 27 publications

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“…A recent report shows achiral 5CB can form helical chiral phase when doped with a trace amount chiral molecule. [71] In our study, C153 is a chiral molecule and its presence may help 5CB and 8CB for adopting chiral phase. Due to the asymmetric packing, a finite angle is maintained between two adjacent layers of LC molecules, giving rise to a long range chirality.…”

Section: Study Of Rotational Anisotropy Decay Of C153 In Lcsmentioning

confidence: 77%

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Probing of Reorganization Dynamics within the Different Phases of Themotropic Liquid Crystals

et al. 2018

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Solvent properties of two liquid crystalline solvents (LCs), 4‐n‐pentyl‐4/‐cyanobiphenyl (5CB) and 4‐n‐octyl‐4/‐cyanobiphenyl (8CB) are studied by exploiting their intrinsic fluorescence. Solvation dynamics of LCs in crystalline, liquid crystalline and liquid phases are observed by utilizing the dynamic Stokes shift in the time resolved emission spectrum (TRES) of an excited dye molecule coumarin 153 (C153) immersed within the LCs. With increasing temperature, transitions occur from crystalline to smectic/nematic and finally to liquid phase for these thermotropic LCs. At high temperature, liquid crystalline phases with substantial orientational orders are transformed to isotopic liquid phases. In this phase, peak positions of intrinsically fluorescent LCs are shifted towards the higher energy side with lowering its fluorescence quantum yields (φf) as compared to the emission peak positions and quantum yields of LCs in other anisotropic phases. Solvation dynamics study shows that the average solvation time of C153, immersed within the liquid phases of LCs, is about an order of magnitude faster as compared to that within a crystalline phase of the same substrate (5CB or 8CB). This observation is substantiating the fact that even within a complete crystalline phase a fluid like motion of the LC solvent molecules still exists. Average solvation time of C153 follows a descending order when we move from a complete crystalline phase to liquid crystalline phase to complete liquid phase.

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Section: Study Of Rotational Anisotropy Decay Of C153 In Lcsmentioning

confidence: 77%

“…However, 5CB and 8CB are achiral molecules and therefore formation of chiral nematic phase is not likely to happen here. A recent report shows achiral 5CB can form helical chiral phase when doped with a trace amount chiral molecule . In our study, C153 is a chiral molecule and its presence may help 5CB and 8CB for adopting chiral phase.…”

Section: Resultsmentioning

confidence: 99%

Probing of Reorganization Dynamics within the Different Phases of Themotropic Liquid Crystals

et al. 2018

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“…It is found that chiral dopants generate strong helicity in the nematic phase, and the strength of a dopant to generate a helical structure is called helical twisting power (HTP). Rudquist et al [63] found that 5CB molecules formed a helical structure when doped with chiral mandelic acid with hydroxy. Kishikawa et al [64] found that the substituents of a series of chiral succinimide derivative significantly affected the formation of a helical structure of 5CB, and the derivative with a terminal hydroxyl resulted in a larger HTP than the derivative with a terminal alkyl.…”

Section: Effect Of Polarity On Molecular Orientationmentioning

confidence: 99%

Molecular behaviors in thin film lubrication—Part one: Film formation for different polarities of molecules

et al. 2019

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There are three unsolved problems in thin film lubrication (TFL) since it was proposed 20 years ago, i.e., the determination of the type of molecules that can enter the contact region efficiently during sliding, the orientation of molecules in the contact region, and the effect of solid surfaces on the liquid molecular orientation in TFL. In order to answer the first two questions, an in situ measurement system comprising a self-designed Raman microscopy and relative optical interference intensity (ROII) system was set up to study the molecular behaviors. A variety of binary mixtures were used as lubricants in the test, and the concentration distribution profile and orientation of the additive molecules in TFL were characterized. The molecular behavior was determined via a combination of shearing, confinement, and surface adsorption. Furthermore, the difference in molecular polarity resulted in different competing effect of surface adsorption and intermolecular interaction, the influence of which on molecular behavior was discussed. Polar additive molecules interacted with the steel surface and exhibited an enrichment effect in the Hertz contact region when added into a nonpolar base oil. No enrichment effect was observed for nonpolar molecules that were added into the nonpolar base oil and polar molecules added into polar base oil. The enrichment of additive molecules enhanced the film-forming ability of the lubricant and resulted in a reduction in the friction coefficient of up to 61%. The orderly arrangement of the additive molecules was another reason for the friction-reducing. A binary multilayer model was proposed to illuminate the molecular behavior in the TFL, and the model was supported by contrary experiment results in elastohydrodynamic lubrication. This research may aid in understanding the nanoscale lubrication mechanism in TFL and the development of novel liquid lubricants.

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Can elastic constants and surface alignment be obtained from polarized microscopy images of nematic droplets? A Monte Carlo study

Chiccoli

Pasini

Zannoni

2018

Journal of Molecular Liquids

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Chirality Detection Using Nematic Liquid Crystal Droplets on Anisotropic Surfaces

Cited by 4 publications

References 27 publications

Probing of Reorganization Dynamics within the Different Phases of Themotropic Liquid Crystals

Probing of Reorganization Dynamics within the Different Phases of Themotropic Liquid Crystals

Molecular behaviors in thin film lubrication—Part one: Film formation for different polarities of molecules

Can elastic constants and surface alignment be obtained from polarized microscopy images of nematic droplets? A Monte Carlo study

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