SANS investigation of structure and stability of water/AOT/dodecane microemulsion droplets

Abstract

The formation and stabilization of water/AOT/dodecane microemulsion (water in oil) droplets by employing Small Angle Neutron Scattering (SANS) is demonstrated. The resulting structure exhibits strong inter-droplet attractive interaction that can be tuned by molar ratio (W) of water to AOT concentration. The strengthening of the inter-droplet attractive interaction with increase in W has been modeled using modified Ornstein-Zernicke relation. We further demonstrate that on addition of salt (NaCl), the inter-droplet attractive interaction is substantially weakened and hence the droplet stability is enhanced. The SANS data analysis confirms the monotonic decrease in both the correlation length and compressibility with increase in salt concentrations indicating the formation of microemulsion droplet system with increased stability and that the stability could be achieved for higher values of W with salt.