Dynamic light scattering observation of droplet aggregation in a Winsor type W/O microemulsion system

We have performed scattered light intensity autocorrelation measurements on a Winsor type microemulsion system composed of brine, cyclohexane, SDS and a mixture of 1-butanol and 1-pentanol. At high cosurfactant concentration, where the microemulsion phase was considered to consist of individual, spherical water-in-oil droplets of relatively low droplet volume fraction, the autocorrelation functions were observed to be essentially single exponential, as expected. Above a certain droplet volume fraction, however, additional decay modes were observed to enter the correlation data. These modes were interpreted to be due to rotation and/or internal motion of droplet aggregates.