Investigations of microemulsions by light scattering and neutron scattering

Abstract

Microemulsions formed from water, xylene, sodium dodecyl benzene sulphonate and hexanol have been investigated by three different scattering techniques, namely, time-average light scattering (l.~.), small-angle neutron scattering (SANS) and photon correlation spectroscopy (P.c.s.). The water volume fraction in this water-in-oil system, which was investigated at a constant molar ratio (hexanol : sodium dodecyl benzene sulphonate) of 3.28, was vaned from zero to 0.533. Over most of the volume-fraction range the droplets were strongly interacting. The problem of obtaining information about the variation of particle size with volume fraction from scattering techniques in strongly interacting systems is discussed in some detail and a possible theoretical approach suggested based on the use of a hard-sphere interaction model. The combination of ls., SANS and P.C.S. is shown to be an excellent one for problems of this type, in that 1.s. and SANS can provide time-average structural information and P.C.S. dynamic information about the motion of the particles in strongly interacting systems. With the model proposed the information from the three experimental techniques was found to be self-consistent. For the system investigated the radius of the water core of the droplet was found to increase with increase in the water volume fraction whilst apparently maintaining a constant water-oil interfacial area.

Diffusion of spheres in a concentrated suspension: Resummation of many-body hydrodynamic interactions

“…2 we have plotted the concentration dependence of the two limits [4] is obtained, up to the highest (experimental) volume fractions. The experimental data [6,7] forD c indicate that this quantity is rather insensitive to changes in the concentration over a large ränge of volume fractions; a remarkable result, which is confirmed by our calculations.…”

Kinetics of the Formation of Nano-Sized Platinum Particles in Water-in-Oil Microemulsions

“…With this α value the correction of the hydrodynamic radii, obtained in this work, was less than 5%. The small particle interaction influence was probably related to the low water content (φ aq ≤ 0.02) in the system (21).…”

Studies of particle-particle interactions using polystyrene latices and time-average light scattering

“…However, at higher concentrations of latex, a more appropriate multibody approach was required. Since, as mentioned above, latices under these conditions show many analogies with the behaviour of liquids, the use of a hard sphere potential of the Percus-Yevick type [14,15] was explored and found to give a reasonable correlation with experiment. It was then possible to use the latter approach to predict the behaviour of more concentrated systems.…”