Effect of alkyl chain length and head group on surface active and aggregation behavior of ionic liquids in water

Surface adsorption and micelle formation of imidazolium-based zwitterionic surface active ionic liquids in aqueous solution

“…Synthesis of [NAC n , N 0 ACO 2 HAIm] (n = 10,12,14) Carboxylate functionalized imidazolium-based zwitterionic SAILs were prepared as improved procedures based on the literatures [30,33]. N-alkylimidazole was prepared as described previously [30].…”

“…Imidazolium-based SAILs have been most studied in the field of colloid and interface chemistry. Numerous SAILs based on imidazolium, pyridinium, pyrrolidinium cations with different hydrocarbon chain lengths were studied extensively using a variety of methods, such as surface tension, 1 HNMR, steady-state fluorescence spectroscopy, and conductivity measurements [10][11][12][13][14]. Additionally, the effects of anionic nature (e.g., Cl À , Br À , NO À 3 , I À , BF À 4 , CF 3 SO À 3 , CH 3 COO À , ClO À 4 ) [15][16][17][18], various organic additives [19], and salts [20] on the aggregation behavior of SAILs in aqueous solutions were investigated.…”

“…However, so far the surface adsorption and micellization characteristics of long-chain ZILs have seldom been reported. Tondo et al [32] synthesized an imidazolium-based ZIL with long hydrophobic group, 3-(1-tetradecyl-3-imidazolio)propane-sulfonate (ImS3- 14), and evaluated the chameleon-like behavior of zwitterionic micelles. They found its solubility was very low, and it became readily soluble in 0.08 mol L À1 NaCl (or NaClO 4 ) at 298 K, but both the micellar aggregation number and the critical micelle concentration were only slightly sensitive to added salts.…”

“…They are denoted as [NAC n , N 0 ACO 2-AIm] (n = 10,12,14) with the chemical structures represented in Fig. 1.…”

Small-Angle X-Ray Scattering of Ionic Liquids

“…While this does provide information about the local order of the micelles, information, such as micelle size, is not provided. In other cases, the form factor for an ellipsoid has been used instead to resolve micelle size [68,69]. In these cases, not all the micelle information was resolved from the SAXS data.…”