Effect of ionic liquids on temperature-induced percolation behavior of AOT microemulsions

The effect of ionic liquids (ILs) on temperature-induced percolation of water/sodium bis-(2-ethylhexyl) sulfosuccinate (AOT)/isooctane microemulsions was investigated. Several properties of microemulsions, including percolation temperature threshold (T-p), viscosity, and droplet size were used to demonstrate the effect of the structure of ILs on percolation phenomena. Percolation phenomena of microemulsions were clearly observed after the addition of IL, and the T-p of microemulsions increased with increases in the ILs concentration. In addition, T-p was greatly affected by the alkyl side-chain length of imidazolium cation and increased with increases in chain length. However, T-p was slightly affected by the ILs anions due to the charge exclusion caused by the head group of surfactant. Additionally, the viscosity and droplet size of microemulsions decreased with the addition of ILs, and the observed decrease correlated roughly with an increase in T-p. These results also confirm the influence of ILs on percolation phenomena of the microemulsions. (C) 2012 Elsevier B.V. All rights reserved.