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 (Tp), 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 Tp of microemulsions increased with increases in the ILs concentration. In addition, Tp was greatly affected by the alkyl side-chain length of imidazolium cation and increased with increases in chain length. However, Tp 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 Tp. These results also confirm the influence of ILs on percolation phenomena of the microemulsions.

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► Temperature-induced percolation of microemulsions with ionic liquid (IL) was studied.
► Percolation temperature (Tp) of microemulsions increases with the addition of IL.
► Tp is greatly affected by the alkyl side-chain length of imidazolium cation of IL.
► The viscosity and droplet size of microemulsions decrease with the addition of IL.
► The decrease of viscosity and droplet size correlate roughly with an increase in Tp.