Investigation of the effect of silica sources on ionogels prepared from imidazolium based ionic liquid via sol-gel method

Abstract

Ionic liquids have many interesting properties such as low vapor pressure, wide liquid range, non-volatility, ionic conductivity, and high thermal stability. Even though these properties make ionic liquids a good alternative in various technological devices; problems such as leakage and portability limits the the use of ionic liquids. In recent years, ionogels have gained significant value by overcoming the liquid form problems and by preserving the basic properties of ionic liquids. In this study, imidazolium based ionic liquid was changed to ionogel by using a silica source such as tetraethylorthosilicate (TEOS), tetramethylortosilicate (TMOS) and methyltrimethoxysilane (MTMS), and formic acid was used as both solvent and catalyst. The effects of different silica sources, molar ratios of components, gelling and aging time on ionogel formation were investigated by experimental studies. Synthesized ionogels were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy and Ultraviolet-Visible (UV-Vis) Spectroscopy analyzes. The stable ionogels were obtained with 1: 8 silica: formic acid molar ratio, 96 hours of gelation time and 8 days of aging time. It has been determined that the synthesized ionogels have smooth and transparent structure.