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Self–aggregation Behavior of Dialkyl Imidazolium based Ionic Liquids in Aqueous Medium: Effect of Alkyl Chain Length
Author(s) -
Chabba Shruti,
Vashishat Rajni,
Kang Tejwant S.,
Mahajan Rakesh K.
Publication year - 2016
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201600301
Subject(s) - ionic liquid , isothermal titration calorimetry , dynamic light scattering , alkyl , micelle , chemistry , aqueous solution , aggregation number , adsorption , transmission electron microscopy , chemical engineering , titration , nanoparticle , critical micelle concentration , organic chemistry , catalysis , engineering
A series of new dialkyl imidazolium based ILs viz. N‐butyl‐N‐alkylimidazolium bromides, [C m C n mim][Br], where m=4, n=4, 8 and 12 have been synthesized, characterized and investigated for their self‐aggregation behavior in aqueous medium. Various techniques such as tensiometry, steady state fluorescence, isothermal titration calorimetry (ITC), dynamic light scattering (DLS), transmission electron microscopy (TEM) and 1 H nuclear magnetic resonance (NMR) have been employed to get detailed information about the self‐aggregation phenomenon. The investigated ILs have shown better adsorption and micellization behavior in comparison to single chain imidazolium based ILs in terms of higher adsorption efficiency and lower cmc values. TEM measurements provided insights into morphology of aggregates where spherical micelles and doughnut shaped vesicle like structures have been observed depending on the molecular structure of IL. The structure of aggregates formed by these ILs at molecular level has been proposed by analyzing the change in chemical shifts of various protons of ILs upon micellization along with information obtained from other techniques.