Ionic liquids in the synthesis and modification of polymers

Abstract

Ionic liquids are organic salts that are liquid at ambient temperatures, preferably at room temperature. They are nonvolatile, thermally and chemically stable, highly polar liquids that dissolve many organic, inorganic, and metallo-organic compounds. Many combinations of organic cations with different counterions are already known, and the properties of ionic liquids may be adjusted by the proper selection of the cation and counterion. In the last decade, there has been increasing interest in using ionic liquids as solvents for chemical reactions. The interest is stimulated not only by their nonvolatility (green solvents) but also by their special properties, which often affect the course of a reaction. In recent years, ionic liquids have also attracted the attention of polymer chemists. Although the research on using ionic liquids in polymer systems is still in its infancy, several interesting possibilities have already emerged. Ionic liquids are used as solvents for polymerization processes, and in several systems they indeed show some advantages. In radical polymerization, the k p /k t ratio (where k p is the rate constant of propagation and k t is the rate constant of termination) is higher than in organic media, and thus better control of the process can be achieved. Ionic liquids, as electrolytes, have also attracted the attention of researchers in the fields of electrochemical polymerization and the synthesis of conducting polymers. Finally, the blending of ionic liquids with polymers may lead to the development of new materials (ionic liquids may act as plasticizers, electrolytes dispersed in polymer matrices, or even porogens). In this article, the new developments in these fields are briefly discussed.

Ionic Liquids in Photopolymerizable Holographic Materials

“…Ionic liquids have significant influence on the kinetics of various polymerization reactions [26][27]. The nature of ionic liquids has strongly influenced the polymerization rate and conversion of oligomer.…”

“…6 ] can improve the sensitivity of the materials, only the former gave rise to high diffraction efficiency. This may be due to the different solubility property, viscosity or polarity of ionic liquids [27]. Additionally, we have also looked after the morphology of the gratings with scanning electron microscopy.…”

“…The number of possible cation-anion combinations is greater than one million, thus allowing the design of tailor-made ionic liquids for a desired task. Ionic liquids have also attracted the attention of polymer chemists [26][27][28][29][30]. Ionic liquids have been used as reaction media in several types of polymerization processes, such as free radical polymerization [31, controlled radical polymerization [32-33}, ring-opening polymerization [34], anionic/cationic polymerization [35], enzymatic polymerization [36], and microwaveassisted polymerization [37] and electrochemical polymerization [38].…”

Hydrophobic Poly(ionic liquid) for Highly Effective Separation of Methyl Blue and Chromium Ions from Water

“…Ionic liquids (ILs), which are organic salts with melting temperature below 100 °C, have attracted significant interest due to good chemical and electro-chemical stability properties such as high ionic conductivity, polarity, heat capacity and thermal stability [7][8][9][10][11]. The functionality of ILs is tunable by adjusting molecular structures of the organic asymmetric cations (e.g., imidazolium, pyridinium, and tetraalkylammonium) and anions (e.g., halide, tetrafluoroborate, hexafluorophosphate, triflate, amidotriflate, dicyanamide) [12][13][14][15].…”

Intrinsic Viscosity of Pullulan in Ionic Liquid Solutions Studied by Rheometry

“…1) Because of its unique characteristics such as extremely low vapor pressure, thermal stability, and high ionic conductivity, ILs are widely used in many fields of science and engineering. [2][3][4][5][6][7][8] Among them, imidazolium-based ILs have been tested as solvent for the so-called insoluble natural polymers such as cellulose and silk fibroin. 1-butyl-3-methylimidazolium chloride (BmimCl) 9) , 1-allyl-3-methylimidazolium chloride (AmimCl) 10) and 1-ethyl-3-methylimidazolium acetate (EmimAc) 11) have been focused on as new green solvents for cellulose.…”