Morphological transformations in Triton X-100 micelles modulated by imidazolium and pyridinium type Ionic Liquids: Investigations by scattering techniques

The phase behaviour and aggregation characteristics of aqueous solution of Triton X-100 in the presence of several 1-alkyl-3-methylimidazolium salts, [C_nmim⁺]X⁻ and 1-alkylpyridinium salts [C_nPy⁺]X⁻, where n is the alkyl chain length (4,6,8.10) and X⁻ is the anion CF₃SO₃⁻ and BF₄⁻ has been explored. The effect of nonpolar alkyl chain length, cation and anion of these ionic liquids was investigated from cloud point (CP), dynamic light scattering (DLS) and small angle neutron scattering (SANS). ILs with longer alkyl chain on cation drastically increased CP and decreased micelle size. The size, hydrophobicity and polarity of anions also showed marked effect on solution behavior of Triton X-100. The results indicate opposite effect on CP and hydrodynamic diameter (D_h) on addition of ionic salts. SANS results demonstrate that added ILs modulated the size of TX-100 micelle, which is further discussed in terms of penetration of cation and anion into TX-100 micelle depending on the nature of alkyl chain attached to the cation/anion and varying size, hydrophobicity, surface activity of anion.