Relaxation Modes in a TX100 Microemulsion System

Abstract

We have studied oil in water microemulsion system comprising Triton X-100 (TX100) as surfactant, cosurfactant (octanol) and oil (decane) by dynamic light scattering at various concentration. In diluted regime, the autocorrelation function exhibits a nearly mono-exponential relaxation. The best fit is obtained by using the method of cumulant up to order 2. The apparent hydrodynamic radius RHapp and polydispersity index σD were deduced. In concentrated regime, the DLS correlation function exhibit two relaxation modes. According to Pusey and Weissman, the fast one corresponds to collective diffusion coefficient (number density fluctuations) and the slow one corresponds to self diffusion coefficient (polydispersity fluctuation). The variation of Dc and Ds with volume fraction Φ reflects that the droplets interact via an overall repulsive potential.