Structural behavior of the lamellar mesophase formed by ternary mixtures of a two-tailed ionic liquid, 1-decanol and water

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 509; pp. 174 - 181
• Main Authors: Usma, Cesar L., Renamayor, Carmen S., Pacios, Isabel E.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20-11-2016
• Subjects: 1,3-didecyl-2-methyl-imidazolium chloride; Ionic liquid; Lamellar mesophase; Phase diagram; SAXS; Surfactant; R; IL; Lamellar mesophase; Cnmim; 1,3-didecyl-2-methyl-imidazolium chloride; Phase diagram; OH; DDMIC; W#-R; Surfactant; Ionic liquid; SAXS
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2016.09.008

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•The system 1,3-didecyl-2-methyl-imidazolium chloride in decanol/water is studied.•A single lamellar region is extended in a wide range of temperatures and compositions.•The decanol is incorporated in the bilayer as a cosurfactant.•The structural parameters depend on the temperature and the composition.•Ionic liquid-alcohol interactions induce conformational changes of the IL molecule.
The lamellar mesophase of a ternary system involving the ionic liquid 1,3-didecyl-2-methylimidazolium chloride, 1-decanol and water is studied in detail. Small and wide X-ray diffraction with synchrotron radiation, optical microscopy and differential scanning calorimetry are employed to determine the phase diagrams and the changes in the structural parameters of the lamellar structure, considering three variables: (i) the water content, (ii) the molar decanol/ionic liquid ratio and (iii) the temperature. A single lamellar Lα region is extended in a wide range of temperatures and compositions. The corresponding lamellar spacing and the cross-sectional area of the polar head group, display a temperature dependence. When the decanol/ionic liquid molar ratio is greater than 1.5, increasing temperature causes a transition from lamellar to an isotropic phase.