On the alignment of thermotropic nematic and smectic liquid crystals on lecithin coated surfaces

Hiltrop, K.; Hasse, Jörg; Stegemeyer, H.

doi:10.1002/bbpc.19940980213

Cited by 24 publications

(11 citation statements)

References 19 publications

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“…The anchoring behavior of 5CB and 5PCH on lecithin monolayers formed by the Langmuir-Blodgett technique was reported in the literature. 31 On densely packed lecithin monolayers, 5CB showed homeotropic anchoring, while 5PCH showed tilted anchoring, which agrees with our results. The exible and bulky 5PCH requires higher anchoring energy to achieve homeotropic anchoring than rigid 5CB.…”

Section: Resultssupporting

confidence: 91%

Bile acid–surfactant interactions at the liquid crystal/aqueous interface

Liang

Cheng

et al. 2014

Soft Matter

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The interaction between bile acids and surfactants at interfaces plays an important role in fat digestion. In this paper, we study the competitive adsorption of cholic acid (CA) at the sodium dodecyl sulfate (SDS)-laden liquid crystal (LC)/aqueous interface formed with cyanobiphenyl (nCB, n = 5-8) and the mixture of 5CB with 4-(4-pentylcyclohexyl)benzonitrile (5PCH). We find that the critical concentration of CA required to displace SDS from the interface linearly decreases from 160 μM to 16 μM by reducing the alkyl chain length of nCB from n = 8 to n = 5 and from 16 μM to 1.5 μM by increasing the 5PCH concentration from 0 wt% to 19 wt% in the 5PCH-5CB binary mixture. Our results clearly demonstrate that the sensitivity of 5PCH-5CB mixtures for monitoring the interaction between CA and SDS at the LC/aqueous interface can be increased by one order of magnitude, compared to 5CB.

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Section: Resultssupporting

confidence: 91%

Bile acid–surfactant interactions at the liquid crystal/aqueous interface

Liang

Cheng

et al. 2014

Soft Matter

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“…The long-range orientation correlation of the liquid crystal leads to the surface-induced tilt order into the bulk phase. The penetration of the 5CB molecules in lipid monolayers has been reported (28)(29)(30). These studies also show that the 5CB adopt the orientation of the lipid molecules to form a uniformly aligned liquid-crystal layer on the lipid monolayers.…”

Section: Methodsmentioning

confidence: 71%

Liquid-crystal imaging of molecular-tilt ordering in self-assembled lipid tubules

Zhao

Mahajan

Lü

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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Self-assembled cylindrical tubules of chiral phospholipids are interesting supramolecular structures. Understanding the moleculartilt order is a key step in controlling the size and shape of the tubules and designing new functional materials. The current theories based on the chiral interactions, coupled with molecular tilt, have predicted that the tubules could have both uniform and modulated tilt states. Here, we image the molecular-tilt order in the self-assembled tubules of a chiral phospholipid by using liquid crystals as an optical amplification probe. We demonstrate that the organization of the molecular-tilt azimuth in the lipid tubules can induce an azimuthal orientation in the liquid crystals. Both uniform and modulated tilt states of the lipid tubules are observed after liquid-crystal optical amplification.liquid-crystal amplification ͉ molecular ordering ͉ self-assembly ͉ optical amplification ͉ supramolecular structure T he self-assembled cylindrical tubules have attracted considerable attention because of their interesting supramolecular structures and technological applications (1, 2). It has been found that a variety of amphiphilies, including alkylaldonamides (3), diacetylenic phospholipids (4, 5), amino acid-based surfactants (6, 7), and multicomponent mixtures in bile (8, 9), selfassemble into cylindrical tubules in solutions. Recently, advances have been made in controlling the sizes and shapes of tubules by adjusting the chemical compositions and the conditions under which self-assembly occurs (10-16).Theoretical models based on the chiral interactions, coupled with molecular tilt, have been used to explain the formation of the cylindrical tubules (17)(18)(19). In these models, the chiral molecules do not pack parallel to their neighbors but, rather, at a nonzero angle with respect to their neighbors. This chiral packing causes the twisting of a bilayer stripe, which leads to the formation of cylindrical tubules. The model by Selinger et al. (19) suggests that the tubules can have both uniform and modulated tilt states. In the uniform tilt state, the tubule has a constant orientation of the molecule tilt with respect to the equator of the cylinder (Fig. 1a). In the modulated tilt state, the tubule has a periodic modulated structure by helical stripes in the molecular tilted direction winding around the cylinder. The direction of the molecular tilt smoothly varies across the stripes and jumps at the edges of the stripes (Fig. 1b). These stripes in the tubules are suggested to be analogous to the tilted stripes seen in the Langmuir monolayers (20) but in a cylindrical rather than a planar geometry. To our knowledge, there has been no experimental test of the theoretical predictions because of the difficulty in probing the local direction of the molecular tilt in the tubules.In recent years, there has been an increased interest in developing an imaging technique based on liquid-crystal optical amplification for studying the structures and physical properties of organic and biological interfac...

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“…1 been deposited [11][12][13][14][15]. First, the thermodynamic states of the amphiphiles at these interfaces differ from each other: at equilibrium, the chemical potential of a surfactant in a surfactant-laden aqueous-liquid crystal interface is determined by the composition of the surfactant in the bulk aqueous phase.…”

Section: Experimental Geometrymentioning

confidence: 99%