Rheology of Imidazolium-Based Ionic Liquids with Aromatic Functionality

Abstract

A series of imidazolium-based ionic liquids with cyclic and aromatic groups and a bis[(trifluoromethane)sulfonyl]amide anion were characterized using dynamic and steady shear rheology in a wide temperature range. The cations investigated include 1-(cyclohexylmethyl)-3-methylimidazolium ([CyhmC1im](+)), 1-benzyl-3-methylimidazolium ([BnzC1im](+)), 1,3-dibenzylimidazolium ([(Bnz)2im](+)), and 1-(2-naphthylmethyl)-3-methylimidazolium ([NapmC1im](+)). Rheological properties are reported from terminal flow to the glassy state. All ionic liquids show very similar flow behavior with a glassy modulus approaching 1 GPa. The temperature dependences of the shift factors used for time-temperature superposition and the viscosity both follow the same VFT or WLF relationship, and the dynamic fragility at Tg ranges from 117 to 130 for the aromatic ionic liquids investigated, considerably more fragile, in the Angell sense, than the aliphatic analogs. Additionally, an anomalous aging effect in the dynamic viscosity response (i.e., a maximum observed at intermediate frequencies) was found using a strain-controlled rheometer but not using a stress-controlled rheometer.

Rheological behavior of multiwalled carbon nanotube-imidazolium tosylate ionic liquid dispersions

“…Shear thinning of ILs has been reported previously in the literature because of the existence of liquid phase aggregates or networks [24,28,29]. This non-Newtonian behavior has been ascribed to molecular layering in the case of imidazolium-based ILs [30,31].…”

Kinetic Study of Curing Bisphenol A Dicyanate Ester with Ionic Liquid Additive

“…In addition, limited work was performed with an aliphatic cation, 1‐nonyl‐3‐methylimidazolium, ([C 9 C 1 im] + ), as shown in Figure (d). The synthesis of the ILs was reported previously . The glass transition temperature T g and the density are reported to be −58.3 °C and 1.493 g/cm 3 for [BnzC 1 ][NTf 2 ] and −84.1 °C and 1.561 g/cm 3 for [C 9 C 1 im][NTf 2 ] .…”

Ionic Liquids as Environmentally Benign Electrolytes for High‐Performance Supercapacitors

“…[19] On the other side, ions of ILs having no or low symmetry limit their packing into a crystal structure of low melting points. [36][37][38][39] ILs are mostly made up of organic bulky cations (e.g., quaternary ammonium NR 4 + , pyrrolidinium Pyr, imidazolium Im, etc.,) and inorganic or organic charged localized anions (e.g., triflate also known as trifluoromethanesulfonate CF 3 SO 3 − , hexafluorophosphate PF 6 − , halides X, tetrafluoroborate BF 4 − , dicyanamide DCA − , etc.). The insignificant vapor pressure of these substances is a result of the strong interaction among their constituent ions, [40] thus their atmospheric volatile organic compounds' (VOCs) contribution is null.…”