Mesomorphism of Homologous Series

Ennulat, Reinhard D.

doi:10.1080/15421406908084907

Cited by 57 publications

(12 citation statements)

References 9 publications

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“…The solid --+ cholesteric mesophase transition agrees well with the observations by Sell [10], Ennulat [2], and Davis [3]. The cholesteric e-> isotropic-liquid transition temperature of the synthetic sample is above those reported by Sell and Neumann [10] and Porter, Barrall and Johnson [6], but agrees well with those of Davis and Porter [3], Ennulat [2] and Gray [9]. The palmitate sample originally studied by Barrall, Porter and Johnson [6] was probably about 96 percent pure, which is low by present standards.…”

Section: Scanning Calorimetrysupporting

confidence: 89%

“…The smectic --+ cholesteric transition temperature and entropy compare closely to the synthetic sample and the data reported by Davis and Porter [3]. In addition, the transition occurs at a lower temperature than those observed by Gray [9] and by Ennulat [2]. The cholesteric --+ isotropic-liquid transition temperature is in agreement with that observed by Davis and Porter [3].…”

Section: Scanning Calorimetrysupporting

confidence: 89%

“…The present study was concerned with the investigation of the possible solid-phase polymorphy or selective impurity depression of cholesteryl palmitate. This ester has been reported by a number of workers [2,3,6,9,10] to undergo a transition to the cholesteric mesophase on heating, followed by a cholesteric~isotropic liquid transition. On cooling the isotropic liquid, the cholesteric mesophase forms.…”

Section: Introductionmentioning

confidence: 73%

“…It is also interesting to note that there is generally excellent agreement among all previous workers who measured transition entropyeven mesophase entropies. This is particularly noteworthy in view of the small size of these transitions and the wellrecognized effects of certain impurities on transition range and temperature [2,7,8].…”

Section: Scanning Calorimetrymentioning

confidence: 99%

“…Since 1967 the thermodynamic properties of these interesting materials have been studied in this series of papers. Valuable insights and contributions have been made by other workers during this same time period [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

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Polymorphism in Cholesteryl Esters: Cholesteryl Palmitate

1971

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The thermal transitions in cholesteryl palmitate, an ester havingliquid-crystalline states, have been evaluatedand compared to previously reported data. A sample synthesized from carefully purified cholesterol and palmitic acid using p-toluene sulfonic acid compared directly with previously reported data. A sampleof recrystallized ester from a commercial source showeda slightlydepressed solid-to-mesophase transition temperature. However, the mesophase proved to be smectic, commonly reported as monotropic with respect to the solid phase. Both smectic-to-cholesteric and cholesteric-to-isotropic-liquid transitions were sharp, indicating a pure material.It is postulated that a specific impurity, possibly an isomeric cholesterol ester, is responsible for this previously unreported effect. This effect of related compound interaction has been reported for nematic-mesophase-forming compounds. Thin layer chromatography, microscopy, depolarized light intensity analysis, differential scanning calorimetry and NMR spectroscopy data are offered in support of this postulate.

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Section: Scanning Calorimetrysupporting

confidence: 89%

Section: Scanning Calorimetrysupporting

confidence: 89%

Section: Introductionmentioning

confidence: 73%

Section: Scanning Calorimetrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Polymorphism in Cholesteryl Esters: Cholesteryl Palmitate

1971

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Liquid Crystalline Solvents as Mechanistic Probes. IV. The Influence of Ordered Media on the Norrish Type II Photoprocesses in α‐Diketones

Nerbonne

Weiss

1979

Israel Journal of Chemistry

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The Norrish II photoreactions of octane‐4,5‐dione (1) and 1,6‐diphenylhexane‐3,4‐dione (2) have been investigated at several temperatures and in isotropic and ordered (liquid crystalline) media. The sole photoproducts detected in all solvents are 1/1 diastereomeric mixtures of α‐hydroxycyclobutanones. The quantum yields for disappearance of 1 and 2 tend to decrease as the temperature increases in all media investigated. Whereas the quantum yield ratio for disappearance of 1 in cholesteric mesophases and hexane is greater than one, the ratio for disappearance of 2 is less than one. Possible explanations for these observations, based upon the influence of solvent order on solute conformational lability, are advanced.

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Structural investigations of polymer liquid‐crystalline solutions: Aromatic polyamides, hydroxy propyl cellulose, and poly(γ‐benzyl‐L‐glutamate)

Onogi

White

Fellers

1980

J. Polym. Sci. Polym. Phys. Ed.

109

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A comparative structural investigation of the characteristics of polymer liquid‐crystalline solutions including Kevlar® (PPD‐T)/sulfuric acid, poly(Cl‐p‐phenylene terephthalamide) (Cl‐PPD‐T)/sulfuric acid, poly(γ‐benzyl‐L‐glutamate) (PγBLG)/dioxane, and hydroxypropyl cellulose (HPC)/water was undertaken. Experimental procedures included polarized light microscopy, light scattering, absorption spectra, and x‐ray diffraction on solutions at various concentrations and temperatures. Both the two‐phase region at the onset of liquid‐crystal formation and the wholly anisotropic phase were investigated. Each solution exhibited distinctive characteristics. The PPD‐T and Cl‐PPD‐T solutions were nematic, and the PγBLG and HPC solutions were cholesteric. In the two‐phase region the PPD‐T, Cl‐PPD‐T, and PγBLG (but apparently not the HPC) exhibited negatively birefringent spherulites and aggregates of spherulites. The HPC solutions only exhibited spherulitic structures in the single‐phase anisotropic system. The structures and orientations in the anisotropic phase for the various polymer solutions is considered. The helicoidal structural characteristics of the PγBLG and HPC solutions are contrasted.

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Mesomorphism of Homologous Series

Cited by 57 publications

References 9 publications

Polymorphism in Cholesteryl Esters: Cholesteryl Palmitate

Polymorphism in Cholesteryl Esters: Cholesteryl Palmitate

Liquid Crystalline Solvents as Mechanistic Probes. IV. The Influence of Ordered Media on the Norrish Type II Photoprocesses in α‐Diketones

Structural investigations of polymer liquid‐crystalline solutions: Aromatic polyamides, hydroxy propyl cellulose, and poly(γ‐benzyl‐L‐glutamate)

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