Transitional liquid crystalline phases between the hexagonal and lamellar phases in ternary cesium N-tetradecanoate-water-additive mixtures

Journal Article · Thu Apr 01 00:00:00 EST 1993 · Journal of Colloid and Interface Science; (United States)

DOI:https://doi.org/10.1006/jcis.1993.1162· OSTI ID:6482937

Blackburn, J C; Kilpatrick, P K ^[1]

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1. North Carolina State Univ., Raleigh (United States)

The effects of added salt (CsOH, CsCl), long-chain carboxylic acid, and long-chain alcohol on the lyotropic liquid crystalline phase behavior in the cesium n-tetradecanoate (CsTD)-water system is reported. The transitional region between the hexagonal (H) and lamellar (L) phases was the compositional range of focus. Three transitional phases were observed: (i) the ribbon (R) phase, a biaxial phase consisting of cylinders of ellipsoidal cross section; (ii) the viscous isotropic (VI) phase, an isotropic phase thought to consist of interconnected rods on an Ia3d lattice; and (iii) the intermediate (Int) phase, a uniaxial anisotropic phase thought to consist of interconnected rods on a planar lattice. The effect of the additives was to decrease the interfacial curvature of the surfactant head group layer by varying head group repulsion and by varying the surfactant tail volume relative to the surfactant head group area. These changes resulted in formation of transitional phases seeming to possess curvature between that of the cylindrical H phase and the planar L phase. The ionic repulsion between carboxylate head groups was reduced by the addition of CsOH or CsCl, and resulted in destabilization of the VI phase and the formation of the anisotropic Int phase. With the addition of cosurfactants, n-tetradecanoic acid (TDA) and 1-tetradecanol (TDOH), no Int phase was observed. With 7 wt% added TDA the R phase was stabilized up to temperatures of 336 K, above the 330 K temperature limit in the binary CsTD-D[sub 2]O system. In all four systems, sufficient additive (5-10 wt%) resulted in a transition to the L phase, which was stable over a large portion of the compositional range. In order of apparently decreasing mean curvature, the phase sequence is: hexagonal, ribbon, viscous isotropic, intermediate, and lamellar.

• OSTI ID: 6482937
• Journal Information: Journal of Colloid and Interface Science; (United States), Vol. 157:1; ISSN 0021-9797
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CESIUM COMPOUNDS
PHASE STUDIES
ADDITIVES
ALCOHOLS
CARBOXYLIC ACIDS
CATALYTIC EFFECTS
CESIUM CHLORIDES
CESIUM HYDROXIDES
DECANOIC ACID
SHAPE
SURFACTANTS
ALKALI METAL COMPOUNDS
CHLORIDES
CHLORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXIDES
HYDROXY COMPOUNDS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
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OXYGEN COMPOUNDS
400201* - Chemical & Physicochemical Properties