Effects of the alkyl-chain length on the mixing state of imidazolium-based ionic liquid–methanol solutions

• DOI: 10.1039/c0cp00614a
• Publication Date: 2010-08-19T11:00:19Z
• Authors: Takuya Shimomura; Kenta Fujii; Toshiyuki Takamuku
• Keywords: Mole fraction

Effects of the alkyl-chain length imidazolium cation on mixing state imidazolium-based ionic liquids, 1-alkyl-3-methylimidazolium (Cnmim+, lengths n 4, 6, 8, 10, and 12) bis(trifluoromethanesulfonyl)amide (TFSA−), methanol were investigated using small-angle neutron scattering (SANS), attenuated total reflectance infrared (ATR-IR), NMR techniques. SANS measurements revealed that Cnmim+TFSA− is heterogeneously mixed with in mole fraction range 0.8 ≤ xCD3OD 0.995. The heterogeneity Cnmim+TFSA−–methanol solutions, except for C4mim+TFSA−, most enhanced at ≈ 0.97 over entire range. Thus, maximum solutions independent length. In contrast, magnitude larger order from = 4 to 12. ATR-IR showed molecules gradually form hydrogen bonds among them increasing xCH3OH. particular, hydrogen-bonds are conspicuously evolved above xCH3OH 0.8. increase concentration hydrogen-bonded does not significantly depend According these results, we concluded arises polar domains composed rings, TFSA−, clusters nonpolar formed by interaction alkyl chains cations.