Structure and dynamics of micelles and cubic phase structures with ethoxylated phytosterol surfactant in water.
The self-assembly of a sterol ethoxylate surfactant with 30 oxyethylene units in water was studied by 1H NMR self-diffusion measurements in a wide concentration range in the micellar region (0-25 wt %). The data showed that the surfactant aggregates do not interact by hard sphere interactions but rather a strong concentration dependence of the diffusion coefficient was noted which was explained by polymer scaling theory. In the cubic phase (30-65 wt %), the self-diffusion data from water, from surfactant, and from free polyoxyethylene suggest spherical micelles, although water diffusion was much restricted due to binding to the surfactant headgroup. From X-ray measurements in the cubic phase, the unit cell size was calculated, and together with surfactant self-diffusion measurements the exchange dynamics between free and aggregated surfactant was obtained.
Folmer
Britta M
BM
Nestlé Research Centre, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland.
Nydén
Magnus
M
D004058:Diffusion; D005026:Ethylene Glycols / Q000737:chemistry*; D008823:Micelles; D015394:Molecular Structure; D010840:Phytosterols / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D005026:Ethylene Glycols; D008823:Micelles; D010840:Phytosterols; D013501:Surface-Active Agents; D014867:Water