Temperature dependence of molecular motion in smectic liquid crystals of hydrated sodium 4-(1'-heptylnonyl)benzenesulfonate

Journal Article · Thu Apr 29 00:00:00 EDT 1982 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100206a048· OSTI ID:6462370

Blum, F D ^[1]; Miller, W G

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1. Drexel Univ., Philadelphia, PA

The surfactant sodium 4-(1'-heptylnonyl)benzenesulfonate (SHBS), upon hydration to form a smectic liquid crystalline phase, exhibits a thermal transition of 1.62 +- 0.22 kcal per mole of SHBS centered at -70/sup 0/C. From measurements of the temperature dependence of the carbon-13 NMR spectra and from the calorimetric studies, transition was identified as the freezing-in of motion of the aliphatic chains and can thus be labeled as the so-called gel-liquid crystal transition observed in phospholipids. The enthalpy and the entropy associated with the transition correspond to a change of approximately one trans-gauche rotation per hydrocarbon tail. A more intense, broad thermal transition with a heat of 15 +- 3 cal per gram of smectic phase is observed from ca. -10 to -50/sup 0/C and shown to come primarily from the feezing-in of bilayer water. At ca. -23/sup 0/C water associated with the ionic groups, as well as the motion of the SHBS head, becomes frozen-in. Several comparisons between SHBS and similar studies on synthetic phosphatidylcholine are made.

• OSTI ID: 6462370
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 86:9; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ALKALI METAL COMPOUNDS
CALORIMETRY
ESTERS
HYDRATION
LOW TEMPERATURE
NMR SPECTRA
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHASE TRANSFORMATIONS
SODIUM COMPOUNDS
SOLVATION
SPECTRA
SPECTROSCOPY
SULFONIC ACID ESTERS
SURFACTANTS
TEMPERATURE DEPENDENCE