Properties and microstructure of mixed reverse micelles of anionic surfactant AOT and nonionic surfactants in n-heptane were investigated using conductivity, fluorescence probe,and dynamic light scattering. As in the reverse micelle formed with AOT alone, a conductivity maximum was also observed in conductivity-W,(molar ratio of water to surfactants) curves for mixed reverse micellar systems, and W0,mex (W, at the conductivity maximum) moves to a smaller value with the increase of nonionic surfactants contents and their EO chain length. This phenomenon was interpreted in terms of the results of dynamic light scattering and the microstructure of the mixed reverse micelles. The fluorescent behaviour of fluorescence probe Ru(bPy)2+ in mixed reverse micelles indicates that W0, at which the hydration of head groups of surfactants finished, decreases with the increase of nonionic surfactants contents, but increases with their EO chain length at a constant ratio of nonionic surfactants to AOT.
