Interactions of Silica Nanoparticles and Ionic Liquids Probed by High Pressure Vibrational Spectroscopy

Abstract

Gel-like ionic liquid/nanosilica mixtures have been prepared with the addition of 10 wt % nanosilica to 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (EMI+TFSA–), but no changes in C–H spectral features of EMI+TFSA– were observed in the presence of nanosilica under ambient pressure. As the gel-like mixture of EMI+TFSA–/nanosilica was compressed, a new alkyl C–H band at ca. 3017 cm–1 arose. This new spectral feature at ca. 3017 cm–1 may be attributed to the structural reorganization of alkyl C–H groups induced by the interactions between ionic clusters and nanosilica. The imidazolium C–H bands display nonmonotonic shifts as the pressure is elevated. They blue shift slightly initially, but red shifts occur upon further increase of the pressure. The compression also leads to an increase in the relative intensity of the imidazolium C–H band at ca. 3105 cm–1. This observation suggests that some associated species are switched to the isolated form due to the presence of nanosilica under high pressures. In contrast to EMI+TFSA–/nanosilica, the band frequencies and band shapes of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (BMI+TFSA–)/nanosilica are similar to those of pure BMI+TFSA–. These results indicate that the length of alkyl C–H groups plays a nonnegligible role in isolated-associated equilibrium.

Nanoparticles in ionic liquids: interactions and organization

“…Theoretically, the greater the acidity and basicity of the hydrogen bonding atoms, the stronger the hydrogen bond would be. 67,146 The hydrogen bond formation within silica nanoparticles dispersed in imidazolium-based ionic liquid system was studied under ambient and high pressure. 153 Since the hydrogen bond is directional, the steric configuration, such as a bulky side chain, may obstruct hydrogen bond formation.…”

Thermophysical Properties of Nanoparticle-Enhanced Ionic Liquids (NEILs) Heat-Transfer Fluids

“…39 A mixture of 10-20nm silica in 1-butyl-3-methylimidazolium Tf 2 N showed no drastic changes in the C-H bands in the presence of nanosilica at ambient pressure, suggesting the lack of interaction between the silica and the IL ions. 40 X-ray photoelectron spectroscopy suggests the IL cation interacts very strongly with the surface of the carbon black and carbon black surface area decreases by 30%. 41 In comparison, Raman analysis of carbon nanotubes in 1-butyl-3-methylimidazolium hexafluorophosphate show the interactions between the IL and the nanotube are very weak.…”

Detection of Glutamate and Acetylcholine with Organic Electrochemical Transistors Based on Conducting Polymer/Platinum Nanoparticle Composites

“…[12] PEDOT:PSS is a very interesting support electronic hydrogel matrix due to its high degree of porosity (substrate accessibility) and its high electrical conductivity (electronic wiring of Pt NPs). However, most of these studies target energy conversion and energy storage applications.…”