文摘
Aggregation behavior of an imidazolium based ionic liquid (IL), namely 1-dodecyl-3-methylimidazolium chloride [C12mim][Cl] and a surfactant with the same aliphatic chain, dodecyl trimethylammonium chloride (DTAC), are studied and compared in different mole fractions of methanolx2013;water binary solvents using conductometry. From the conductivity data, micellar parameters including critical micelle concentration (CMC), degree of counter ion dissociation (α) and Gibbs free energy of micellization (ΔG°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 [C12mim][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 methanolx2013;water cluster in binary mixed solvents. The changes in CMC of [C12mim][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 (π*) and hydrogen-bond basicity (β) was observed.