Details

Autor(en) / Beteiligte

• Ando, Masatoshi
• Shirota, Hideaki

Titel

Low-Frequency Spectra of 1‑Methyl-3-octylimidazolium Tetrafluoroborate Mixtures with Poly(ethylene glycol) by Femtosecond Raman-Induced Kerr Effect Spectroscopy

Ist Teil von

• The journal of physical chemistry. B, 2021-11, Vol.125 (43), p.12006-12019

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2021

Quelle

MEDLINE

Beschreibungen/Notizen

• This is the first report on low-frequency spectra of ionic liquid (IL)/polymer mixtures using femtosecond Raman-induced Kerr effect spectroscopy. We studied mixtures of 1-methyl-3-octylimidazolium tetrafluoroborate ([MOIm]­[BF4]) and poly­(ethylene glycol) (PEG) with M n = 400 (PEG400) at various concentrations. To elucidate the unique features of the IL/polymer mixture system, mixtures of PEG400 with a molecular liquid, 1-octhylimidazole (OIm), which is a neutral analog of the cation, were also studied. In addition, mixtures of [MOIm]­[BF4] with ethylene glycol (EG) and poly­(ethylene glycol) with M n = 4000 (PEG4000) were also investigated. The first moments of broad low-frequency spectra, mainly due to intermolecular vibrations for the [MOIm]­[BF4]/PEG400 and OIm/PEG400, increased slightly with increasing concentration of PEG400, indicating that microscopic intermolecular interactions, in general, are slightly enhanced. We also compared the [MOIm]­[BF4] mixtures with EG, PEG400, and PEG4000 at concentrations of 5 and 10 wt % PEG or EG. The low-frequency spectra of samples with the same concentrations were quite similar, but a comparison of the normalized spectra showed that the spectral intensity in the low-frequency region below ∼50 cm–1 of the [MOIm]­[BF4] mixtures with PEG400 and PEG4000 is somewhat lower than that of the [MOIm]­[BF4] mixtures with EG. Although the effect of the polymer is small compared to other polymer solution systems, this feature is attributed to a suppression of translational motion in the mixtures of [MOIm]­[BF4] with PEG compared to the mixtures of [MOIm]­[BF4] with EG due to the greater mass of PEG than EG. Density, surface tension, viscosity, and electrical conductivity were also estimated. From Walden plots, it was found that the [MOIm]­[BF4]/PEG4000 system showed more ideal electrical conductive behavior than the [MOIm]­[BF4]/PEG400 and [MOIm]­[BF4]/EG systems.