J. Liu, Y. Li, J.-L. Chai, C.-K. Qin, X.-Y. Yu, Y. Xia
April 2, 2013
The phase behavior and the influencing factors of middle phase microemulsions prepared from surfactant-like ionic liquid 1-alkyl-3-methylimidazolium bromide (C 12 mimBr, C 14 mimBr and C 16 mimBr) were studied systematically with Winsor-type phase diagrams. The minimum alcohol content needed to form the middle phase microemulsion, the alcohol width (the range of the alcohol concentrations from forming to disappearing of the middle-phase microemulsion) and the percent volume of the optimal middle phase at the midpoint of the middle phase region were obtained from the phase diagrams. It was found that with the increase in the carbon chain length of C n mimBr molecules, the minimum alcohol content and the alcohol width decrease, and the solubilization ability (the percent volume of the middle phase microemulsion) increases. With the increase in C n mimBr content, the minimum alcohol content increases, and the alcohol width increases at first and then decreases, and the solubilization ability of the microemulsion systems increases. The minimum alcohol content, the alcohol width and the solubilization ability are also influenced by alcohols, oils and brine. The minimum alcohol content and the alcohol width decrease, and the solubilization ability increases, with the increase in the carbon chain length of the alcohols, the decrease in the carbon chain length of the oils, and the increase in NaCl contents.