Diffusion Measurements in Microemulsions.
Abstract
Diffusion coefficient measurements in both aqueous micelles and microemulsions have been carried out using the techniques of polarography and quasielastic light scattering (QLS). The former method involves the determination of the diffusion coefficient of an electroactive oil soluble probe at a polarizable microelectrode. For high water content microemulsions, both methods yield the same diffusion coefficients which can be identified as the self diffusion coefficient. For cetyltrimethylammonium bromide (CTAB) micelles, both methods yield the same result at the salt (NaBr) concentration at which the QLS measurements are independent of CTAB concentration. In more concentrated microemulsions, QLS data gave diffusion coefficients, in agreement with polarography only for a sodium cetyl sulfate (SCS) system at 65-75 wt % water. For the SCS microemulsions at 60% water, and CTAB microemulsion at 60-75% water, the QLS data yielded rapid, nonexponential decays. However, consistent polarographic diffusion coefficients could still be obtained. By using probes of varying chain length (oil solubility), it has been demonstrated that these CTAB and SCS microemulsions containing butanol and pentanol cosurfactants respectively, are not cosolubilized systems but do contain distinct hydrophilic and hydrophobic regions. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1983
- Accession Number
- ADA133801
Entities
People
- N. S. Dixit
- R. A. Mackay
- R. Agarwal
- Reginald P. Seiders
Organizations
- United States Army Armament Research, Development and Engineering Center