Do alkoxy chains behave like a solvent in the D phase? DSC study of binary systems, ANBC (nC) (nC = 8, 16 and 18)-n-tetradecane

Saito, Kazuya; Sato, Ayako; Sorai, Michio

doi:10.1080/026782998206047

Cited by 63 publications

(27 citation statements)

References 17 publications

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“…The binary system of the nonionic surfactant hexaoxyethylene n-dodecyl ether [n-C 12 H 25 (OCH 2 CH 2 ) 6 OH, abbreviated as C 12 E 6 or C 12 EO 6 ] and water is a typical example showing lyotropic liquid crystals and has been extensively studied. [3][4][5][6][7][8][9][10][11] At concentrations higher than 35 weight percent (35 wt %) of C 12 E 6 , the phase diagram 4 (Figure 1) exhibits three mesophases described above: a hexagonal structure (H I ) of type I (oil in water) at low temperatures and low concentrations, a lamellar structure (L R ) at high temperatures and high concentrations, and at the intermediate oncentration between them a cubic phase (V I ) with space group Ia3d.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Study of Phase Transitions in Lyotropic Liquid Crystals: Adiabatic Calorimetry on Nonionic Surfactant C₁₂E₆−Water System

2001

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The heat capacities of the binary system consisting of a nonionic surfactant, hexaoxyethylene n-dodecyl ether (C 12 E 6 ), and water were precisely measured as a function of temperature by adiabatic calorimetry over the temperature and the concentration ranges where lyotropic liquid crystals are formed. The enthalpy and entropy of transitions were determined for all transitions observed. The enthalpy and entropy of transition between liquid crystalline phases suggest that the liquid crystalline phases in this system are mainly constructed by C 12 E 6 molecules with a fixed amount of water. The excess heat capacities, as estimated by measuring the heat capacity of neat C 12 E 6 , are positive over the entire temperature and concentration ranges. The excess heat capacities also support the suggestion given above concerning the role of C 12 E 6 molecules on the structure building.

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Section: Introductionmentioning

confidence: 99%

Thermodynamic Study of Phase Transitions in Lyotropic Liquid Crystals: Adiabatic Calorimetry on Nonionic Surfactant C₁₂E₆−Water System

2001

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“…22) whereas it was not the case when starting from ANBC (8). 21 These indicate that the alkyl chain certainly contributes, though only in part, to the elongation of the core as assumed by McMillan. 3 It is noted that the induction of SmA phase has been reported for some mixtures of 7CB with other non-smectogenic mesogens, 41,42 or with alkanes.…”

Section: A Phase Diagrammentioning

confidence: 93%

“…21,22 On the basis of this finding, one of the present authors proposed the quasi-binary (QB) picture of thermotropics consisting of mesogens having long alkyl group(s). 23 The QB picture treats a thermotropic LC as a binary mixture of (semi)rigid cores and molten chains.…”

Section: Introductionmentioning

confidence: 96%

Experimental assessment of quasi-binary picture of thermotropics: Induced smectic A phase in 7CB–n-heptane system

Yamaoka

Taniguchi

Yasuzuka

et al. 2011

The Journal of Chemical Physics

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Quasi-binary (QB) picture of thermotropics, which regards a neat thermotropic liquid crystal as a binary system consisting of (semi)rigid core and molten alkyl chain, was assessed experimentally for the most famous (and representative) thermotropic mesogenic series nCB. By adding n-heptane as solvent, the smectic A phase was induced in 7CB-n-heptane system. Small angle x-ray diffraction showed that the QB picture holds not only in the phase behavior but also in the structure. It is suggested that the melting of 8CB and 9CB to isotropic liquid via smectic and nematic liquid crystals can be understood as a thermotropic-lyotropic crossover.

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“…1,2-Bis(4-n-decyloxybenzoyl)hydrazine 631 (4'-n-alkoxy-3'-nitrobiphenyl-4-carboxylic acid) and BABH homologues and the quasi-binary picture, Saito and co-workers suggested that the terminal alkoxy chains of these molecules are more disordered in the cubic phase than in the SmC phase, whereas the spatial arrangement of the molecular core is more ordered in the Cub phase than in the SmC phase [16][17][18][19][20]. This suggestion seems to emphasize the existence of highly disordered alkyl chains in the Cub phase, but we feel rather that the molar volume of the cubic phase is primarily governed not by the highly disordered alkyl chains but by the three-dimensionally connected structure itself; the difference between the Cub and lamellar structures is essential for DVv0 [12].…”

Section: Thermal Behaviour Under Pressurementioning

confidence: 99%

Phase behaviour of the thermotropic cubic mesogen 1,2-bis(4-n-decyloxybenzoyl)hydrazine under pressure

2004

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The phase transition behaviour of an optically isotropic, thermotropic cubic mesogen 1,2-bis(4-n-decyloxybenzoyl)hydrazine, BABH(10), was investigated under pressures up to 300 MPa using a high pressure differential thermal analyser, a wide angle X-ray diffractometer and a polarizing optical microscope (POM) equipped with a high pressure optical cell. The reversible change in structure and optical texture between the cubic (Cub) and smectic C (SmC) phases was associated with a change from a spot-like X-ray pattern and dark field for the Cub phase to the Debye-Sherrer ring pattern and sandlike texture for the SmC phase under both isobaric and isothermal conditions. The Cub phase was found to disappear at pressures above about 11 MPa. The phase transition sequence, low temperature crystal (Cr 3 )-intermediate temperature crystal (Cr 2 )-high temperature crystal (Cr 1 )-Cub-SmC-isotropic liquid (I) observed at atmospheric pressure, is maintained in the low pressure region below 10 MPa. The transition sequence changes to Cr 3 -Cr 2 -(Cr 1 )-SmC-I in the high pressure region. Since the Cub-SmC transition line determined by POM has a negative slope (dT/dP) in the T-P phase diagram, a triple point is estimated approximately at 10-11 MPa, and 143-145 ‡C for the SmC, Cub and Cr 1 phases, giving the upper limit of pressure for the observation of the cubic phase.

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Do alkoxy chains behave like a solvent in the D phase? DSC study of binary systems, ANBC (nC) (nC = 8, 16 and 18)-n-tetradecane

Cited by 63 publications

References 17 publications

Thermodynamic Study of Phase Transitions in Lyotropic Liquid Crystals: Adiabatic Calorimetry on Nonionic Surfactant C₁₂E₆−Water System

Thermodynamic Study of Phase Transitions in Lyotropic Liquid Crystals: Adiabatic Calorimetry on Nonionic Surfactant C₁₂E₆−Water System

Experimental assessment of quasi-binary picture of thermotropics: Induced smectic A phase in 7CB–n-heptane system

Phase behaviour of the thermotropic cubic mesogen 1,2-bis(4-n-decyloxybenzoyl)hydrazine under pressure

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Do alkoxy chains behave like a solvent in the D phase? DSC study of binary systems, ANBC (nC) (nC = 8, 16 and 18)-n-tetradecane

Cited by 63 publications

References 17 publications

Thermodynamic Study of Phase Transitions in Lyotropic Liquid Crystals: Adiabatic Calorimetry on Nonionic Surfactant C12E6−Water System

Thermodynamic Study of Phase Transitions in Lyotropic Liquid Crystals: Adiabatic Calorimetry on Nonionic Surfactant C12E6−Water System

Experimental assessment of quasi-binary picture of thermotropics: Induced smectic A phase in 7CB–n-heptane system

Phase behaviour of the thermotropic cubic mesogen 1,2-bis(4-n-decyloxybenzoyl)hydrazine under pressure

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Thermodynamic Study of Phase Transitions in Lyotropic Liquid Crystals: Adiabatic Calorimetry on Nonionic Surfactant C₁₂E₆−Water System

Thermodynamic Study of Phase Transitions in Lyotropic Liquid Crystals: Adiabatic Calorimetry on Nonionic Surfactant C₁₂E₆−Water System