Amphitropic liquid crystals. Part 1.—Effect of a thermotropic mesogen on lyotropic mesomorphism, and of a surfactant on thermotropic mesomorphism. The C<sub>16</sub>EO<sub>8</sub>–5-CB–water system

Corcoran, Jaqueline; Fuller, Stuart; Rahman, Aminur; Shinde, Neeta; Tiddy, G. J. T.; Attard, George S.

doi:10.1039/jm9920200695

Cited by 19 publications

(17 citation statements)

References 8 publications

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“…[11] reports that, for molecules of elongated shape, β N ∼ −0.58 and β I ∼ −0.51, thus approximately confirming the predicted behavior. A successive study of the effect on the I-N transition of 5CB doped by surfactant molecules of the polyoxethylene family reports β N ∼ −1.35 and β I ∼ −0.95 [12], also is agreement with Eq. 2.…”

Section: A the Phase Diagramsupporting

confidence: 86%

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Pretransitional behavior of a water in liquid crystal microemulsion close to the demixing transition: Evidence for intermicellar attraction mediated by paranematic fluctuations

Caggioni

Giacometti

Bellini

et al. 2005

The Journal of Chemical Physics

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We present a study of a water-in-oil microemulsion in which surfactant coated water nanodroplets are dispersed in the isotropic phase of the thermotropic liquid-crystal penthyl-cyanobiphenyl (5CB). As the temperature is lowered below the isotropic to nematic phase transition of pure 5CB, the system displays a demixing transition leading to a coexistence of a droplet-rich isotropic phase with a droplet-poor nematic. The transition is anticipated, in the high T side, by increasing pretransitional fluctuations in 5CB molecular orientation and in the nanodroplet concentration. The observed phase behavior supports the notion that the nanosized droplets, while large enough for their statistical behavior to be probed via light scattering, are also small enough to act as impurities, disturbing the local orientational ordering of the liquid crystal and thus experiencing pretransitional attractive interaction mediated by paranematic fluctuations. The pretransitional behavior, together with the topology of the phase diagram, can be understood on the basis of a diluted Lebwohl-Lasher model which describes the nanodroplets simply as holes in the liquid crystal.

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Section: A the Phase Diagramsupporting

confidence: 86%

“…) is 10 to 30 times larger than predicted. Indeed, the 5DHµem phase diagram is evidently characterized by a separation between the isotropic and the nematic phase boundaries much larger than those found in refs [11] and [12]. This analysis suggests that, in calculating β, we are overestimating the molar concentration of dopants.…”

Section: A the Phase Diagrammentioning

confidence: 65%

Pretransitional behavior of a water in liquid crystal microemulsion close to the demixing transition: Evidence for intermicellar attraction mediated by paranematic fluctuations

Caggioni

Giacometti

Bellini

et al. 2005

The Journal of Chemical Physics

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“…In previous papers 3,4 we have examined systems where both types of liquid crystal could occur. First, we studied mixtures of conventional thermotropic and lyotropic mesogens, where we found that the mesophases were immiscible . Then we looked at mesophase formation by a compound where thermotropic and lyotropic mesogenic groups were chemically linked via an alkyl chain (spacer) .…”

mentioning

confidence: 99%

Thermotropic and Lyotropic Mesophase Behavior of Amphitropic Diammonium Surfactants

Fuller¹,

Shinde²,

Tiddy³

et al. 1996

Langmuir

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We have synthesized two series of gemini diammonium surfactants with chain terminating poxycyanobiphenyl (OCB) groups (I) or conventional structures (II). The thermotropic mesomorphic behavior of series II has been examined using optical microscopy, differential scanning calorimetry, and X-ray diffraction. All the compounds form one or more smectic phases, at least one of which resembles the smectic T (S T) phase reported by Alami et al. (Liq. Cryst., 1993, 13, 201), where the ionic headgroups form an ordered array, but the chains have some disorder. The exact chain packing differs from that of the ST structure. The lyotropic mesophases formed with water have been investigated for both I and II by optical microscopy and X-ray diffraction (I only). Series II compounds form hexagonal (H1), intermediate (INT) and/or cubic (V1) and lamellar (LR) phases; the size of the spacer group (m) has little influence on this. The OCB compounds all form LR as the only lyotropic mesophase. These results show that the insertion of the rigid terminal OCB moiety has a much larger influence on mesophase structure (and by implication on micelle shape) than the spacer group for m e 6.

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“…The phase diagrams being the results of the studies on phase behavior of polyether type nonionic surfactants in mixtures with water and LABSA sodium salt, disclose the existence of complexed multiphase areas appearing in the range of mass fractions 0.15-0.85 and temperatures between 30 and 90°C. In the case of nonionic surfactants-water system phase diagrams [37][38][39], three liquid crystalline phase areas of lamellar, hexagonal and cubic type occur respectively in the range of mentioned concentration, surrounded with broad region of isotropic micellar liquid, independently of the alkyl chain length (range of C 12 -C 16 ) and the number of oxirane substituents (range of 2-8). A less complex situation occurs in the case of LABSA [23], nevertheless the broad lamellar-lamellar (L 0 a, L 00 a) phase coexistence region is detected in the range of mass fraction 0.25-0.70 determining rheological properties of the system.…”

Section: Effect Of Temperature On the Rheological Behavior Of The Termentioning

confidence: 99%

Rheological Behavior of Selected Water‐Nonionic–Anionic Surfactant Quasi‐ternary Systems

Chruściel¹

2013

J Surfact & Detergents

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The results of studies on the rheological behavior of ternary mixtures comprising water, linear alkylbenzenesulfonic acid, and a non‐ionic surfactant from a group comprising ethoxylated fatty acid methyl esters are presented in this paper. In the latter group, those examined include ethoxylated rapeseed and coconut fatty acid methyl esters, and ethoxylated lauryl acid methyl ester. The flowing curves, effect of temperature on viscosity, as well as the relationship between viscosity and composition of the examined ternary systems were studied. As a practical objective, the studies were intended to utilize the findings for optimizing unit operations which are applied in the process of technology to make washing powder formulations.

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Amphitropic liquid crystals. Part 1.—Effect of a thermotropic mesogen on lyotropic mesomorphism, and of a surfactant on thermotropic mesomorphism. The C₁₆EO₈–5-CB–water system

Cited by 19 publications

References 8 publications

Pretransitional behavior of a water in liquid crystal microemulsion close to the demixing transition: Evidence for intermicellar attraction mediated by paranematic fluctuations

Pretransitional behavior of a water in liquid crystal microemulsion close to the demixing transition: Evidence for intermicellar attraction mediated by paranematic fluctuations

Thermotropic and Lyotropic Mesophase Behavior of Amphitropic Diammonium Surfactants

Rheological Behavior of Selected Water‐Nonionic–Anionic Surfactant Quasi‐ternary Systems

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Amphitropic liquid crystals. Part 1.—Effect of a thermotropic mesogen on lyotropic mesomorphism, and of a surfactant on thermotropic mesomorphism. The C16EO8–5-CB–water system

Cited by 19 publications

References 8 publications

Pretransitional behavior of a water in liquid crystal microemulsion close to the demixing transition: Evidence for intermicellar attraction mediated by paranematic fluctuations

Pretransitional behavior of a water in liquid crystal microemulsion close to the demixing transition: Evidence for intermicellar attraction mediated by paranematic fluctuations

Thermotropic and Lyotropic Mesophase Behavior of Amphitropic Diammonium Surfactants

Rheological Behavior of Selected Water‐Nonionic–Anionic Surfactant Quasi‐ternary Systems

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Amphitropic liquid crystals. Part 1.—Effect of a thermotropic mesogen on lyotropic mesomorphism, and of a surfactant on thermotropic mesomorphism. The C₁₆EO₈–5-CB–water system