Particle size analysis of latex suspensions and microemulsions by photon correlation spectroscopy

The particle size in microemulsions and other highly dispersed systems was determined by means of photon correlation spectroscopy (PCS). As PCS cannot be applied to highly concentrated dispersed phases, the measurement accuracy was tested for its dependence on the particle concentration using latex suspensions. The data obtained by clipping and scaling were compared. The particle size determination was expected to provide information about the influence of the structure of the surfactant system on microemulsions, using a homologous alcohol series as cosurfactant and potassium oleate as surfactant. In this system the region of solubilization is characteristically divided from the region of microemulsification by a zone of instability. Furthermore, there are distinct differences in mean particle sizes between microemulsions (9-30 nm) and micellar solutions (4-6 nm).