In this work, the dynamic behavior of droplets under addition of Dipalmitoylphosphatidylcholine (lipid) and CTAB (salt) is studied by photon correlation spectroscopy. The collective diffusion coefficient (Dc) of Brownian motion of droplets/salt and droplets/lipid was explored by photon correlation spectroscopy (PCS). The PCS experiment demonstrated that Dc of AOT/H2O/n-decane microemulsion increased with increase of lipid and CTAB. For understanding the dynamic of droplets, we investigated viscosity and droplet interaction in Lipid/AOT/H2O/n-decane microemulsion. This system illustrated a well-known maximum in relative viscosity as a function of water/AOT molar ratio near X = 7. The maximum of viscosity can be varied by adding lipid at different concentration. Small angle X-ray scattering measurements revealed that the morphology of droplets changed from cylindrical to spherical with increase of lipid amount in the droplets. The same effect was observed in the mixture of water droplets with CTAB.

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