Evolutionary behaviour of miniemulsion phases: I. Hard sphere interaction and bound water on miniemulsion droplets

Citation
Y. Katsumoto et al., Evolutionary behaviour of miniemulsion phases: I. Hard sphere interaction and bound water on miniemulsion droplets, J PHYS-COND, 12(3), 2000, pp. 249-264
Citations number
50
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF PHYSICS-CONDENSED MATTER
ISSN journal
09538984 → ACNP
Volume
12
Issue
3
Year of publication
2000
Pages
249 - 264
Database
ISI
SICI code
0953-8984(20000124)12:3<249:EBOMPI>2.0.ZU;2-U
Abstract
The interaction between nano sphere droplets in translucent oil in water (O /W) emulsion phases, so-called miniemulsion phases, was investigated by usi ng light scattering measurement techniques. We choose the ternary system of water/hexadecane/Mergital LT7 (the main component is heptaethylene glycol mono-n-dodecyl ether). Rayleigh ratio measurement was performed with changi ng dispersed phase volume fraction phi', and it revealed the fact that the osmotic compressibility is in good agreement with that of a hard sphere flu id. The dependence of the collective diffusion coefficients, measured by dy namic light scattering experiments, is similar to those observed in colloid al hard sphere suspensions. We found out that the ratio of the hydrodynamic diameter to the hard sphere diameter is 1.19 and the volume fraction of di spersed droplets is given by phi = 1.35 phi'. Preparing miniemulsions with various water to oil ratios, it was revealed that the ratio phi/phi' was va ried from 1.01 to 1.33. This indicates that the underestimation of the tota l volume of droplets calculated by the sum of surfactant and oil volume was not negligible. It is therefore considered that the volume fraction of bou nd water on miniemulsion droplets should be taken into account. We briefly discuss the idea that bound water plays an important role in obtaining a ho mogeneous miniemulsion phase.