| Abstract |
Novel functionalized ionic liquid (IL) combining an imidazolium-based cation with branched alkyl chain bearing silyl group, 1-methyl-3-(2-methyl-3-(trimethylsilyl)propyl)imidazolium ([Si-C-1-C-3-mim](+)), and bis(trifluoromethylsulfonyl)imide ([NTf2](-)) anion was synthesized and its thermophysical properties (density, viscosity, surface tension, surface entropy and enthalpy, thermal stability) were studied in a wide temperature range and compared with those of ILs having linear alkyl ([C-n-mim][NTf2]) and siloxane ([(SiOSi)C-1 mim][NTf2]) side chains. It was found that at 25 degrees C [Si-C-1-C-3-mim][NTf2] is a liquid with dynamic viscosity of 224 cP (224 mPas) and density of 1.32 g cm(-3). The presence of side branched alkyl chain with trimethylsilyl end-group prevents crystallization of IL and leads to higher viscosities and lower densities in comparison with commonly known [C-n-mim] [NTf2] (n = 2-4). As surface excess enthalpy was found to be in the lower end of the usual range of values for ILs, the interactions between silyl-functionalized cation and [NTf2] anion can be considered as relatively weak. Finally, [Si-C-1-C-3-mim][NTf2] was used for the preparation of polymer supported ionic liquid membranes (SILMs) and their CO2 and N-2 permeation properties at 20 degrees C and 100 kPa were determined: permeability PCO2 = 311, PN2 = 12 Barrer, diffusivity DCO2 = 115x10(12), DN2 = 227x10(12) m(2) s(-1) and CO2/N-2 permselectivity alpha CO2/N-2 = 25.3. |
