Aggregate Size and Surfactant/Hydrocarbon Diffusion in the Cubic Phase of the Sodium Octanoate/Hydrocarbon/Water System
✍ Scribed by Olle Söderman; Lennart B.-Å. Johansson
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 153 KB
- Volume
- 179
- Category
- Article
- ISSN
- 0021-9797
No coin nor oath required. For personal study only.
✦ Synopsis
phases has been a matter of some controversy (1, 2) regard-The cubic liquid crystalline ( I 1 ) phase formed by sodium octaing questions pertaining to whether the structure is bicontinunoate, n-octane, and water (40.0:4.0:56.0% by weight) was studied ous or built from discrete micelles, and, for the latter case, by means of a fluorescence quenching (FQ) technique. Time rewhether the micelles are spherical or not. A structure that solved fluorescence was measured for small amounts of solubilized is bicontinuous, consisting of a network of short rods with pyrene (P), both with and without a solubilized quencher (Q), encaged spherical micelles, was suggested by the Luzzati dimethylbensophenone. The FQ data show that the Q and P molegroup (4) (although recently this group favors a structure cules are captured in closed amphiphilic aggregates consisting of of discrete micelles (5)). Discrete structures, consisting of ca. 75 sodium octanoate molecules at 298 K. From these results
either spherical micelles (see, e.g., (6, 7)) or (slightly) elontogether with already published X-ray data the number of micelles per unit cell was estimated to be eight. NMR self-diffusion studies gated micelles (see, e.g., (2, 8, 9)), have also been sugof the surfactant and the hydrocarbon were carried out on the gested. One method that can potentially be used to determine above mentioned cubic phase as well as on the corresponding what structure is present is small-angle X-ray scattering. phases formed with p-xylene and cyclohexane. These experiments However, for these systems, one is often faced with the convey information on the lifetime of the surfactant and the hydroproblem of obtaining too few reflections in the diffractocarbon in the aggregates and also on the structure of the cubic grams. Therefore the assignment of a space group is often phase.