Aggregation of imidazolium based ionic liquids in binary methanol-water solvents: A linear solvation free energy relationship study

作者：Hemmateenejad Bahram^*; Safavi Afsaneh; Dorostkar Samira

来源：Journal of Molecular Liquids, 2011, 160(1): 35-39.

DOI：10.1016/j.molliq.2011.02.011

• Ionic liquids
• Aggregation
• Methanol-water
• Linear solvation free energy relationship

Aggregation behavior of an imidazolium based ionic liquid (IL), namely 1-dodecyl-3-methylimidazolium chloride [C(12)mim][Cl] and a surfactant with the same aliphatic chain, dodecyl trimethylammonium chloride (DTAC), are studied and compared in different mole fractions of methanol-water binary solvents using conductometry. From the conductivity data, micellar parameters including critical micelle concentration (CMC), degree of counter ion dissociation (alpha) and Gibbs free energy of micellization (Delta G degrees mic) for both species were calculated as a function of methanol mole fraction. It was found that similar to the surfactant DTAC, the ionic liquid [C(12)mim][Cl] forms micellar aggregation in pure water and methanol as well as in their binary mixtures. The CMC values for both compounds were increased up to a methanol mole fraction of 0.5 and then decreased at higher mole fractions. This was attributed to the preferential solvation and formation of methanol-water cluster in binary mixed solvents. The changes in CMC of [C(12)mim][Cl] and DTAC as a function of methanol mole fraction were also described by changing in solvatochromic properties of solvents through linear solvation free energy relationship (LSFER) study. A linear relationship between log (CMC) and two solvatochromic Kamlet-Taff parameters including polarity/polarizability (pi*) and hydrogen-bond basicity (beta) was observed.

• 出版日期2011-4-15