Synthesis, Solubility And Applications Of N, N'-imidazolium-based Ionic Liquids

Ionic liquids are ionic molten salts that are liquids at normal temperature. They are nonvolatile, nonflammable, extremely high boiling point, recyclable and chemically stable, so they are widely used in organic synthesis, electrochemistry, polymer, nano materials and analytical chemistry. In this paper, ionic liquids were used in natural polymer and inorganic materials.The work in this paper included:1. Ionic liquids of 1-carboxymethyl-3-ethylimidazolium chloride ([CmEIM]Cl), 1-methoxyethyl -3-ethylimidazolium chloride ([C₂OC₁-EIM]Cl) and 1-[2-(2-chloroethoxy) ethyl]-3-ethylimidazolium chloride ([Cl-C₂OC₂-EIM]Cl) were synthesized, and their chemical structures were confirmed by FT-IR and 1H- NMR.2. Dissolution of cotton cellulose in these three kinds of ionic liquids was studied. The chemical structures, morphologies and crystalline forms of the original cellulose and the regenerated cellulose were analyzed by FT-IR, XRD and SEM respectively. The results show that the solubility of cotton cellulose in [C₂OC₁-EIM]Cl was best. In the dissolution process, the solubility of cotton cellulose in the ionic liquids increased with temperature increasing, but the DP decreased, especially in [Cl-C₂OC₂-EIM]Cl. It was suggested that the solubility of cotton cellulose in [CmEIM]Cl containing carboxyl decreased because of its intermolecular and intramolecular hydrogen bonds. The ionic liquids with long side chains exhibited worse dissolution ability for cotton cellulose.3. Liquefaction of fir powder in ionic liquids was studied. The product of liquefaction was used to modify phenolic resin adhesives. The reaction efficiency of liquefaction was affected by reaction temperature, reaction time, liquid ratio and different ionic liquids. The content of free formaldehyde in the adhesives decreased, but the tensile shear performance improved. The ionic liquids in the adhesives played an important role in adhesive capability.4. Organic modified montmorillonite was prepared with ionic liquids as the intercalation agent, and the space between was studied. It was shown that the space between of organic modified montmorillonite increased, and the ion-exchanging reaction could happen without water. SiO₂ nanoparticles were prepared with ionic liquids. Interaction between ionic liquid and SiO₂, and the crystalline form of SiO₂ were studied. There were no chemical reactions between ionic liquids and SiO₂. SiO₂ nanoparticle elementarily has crystalline structure after calcination at 1200℃, but SiO₂ nanoparticles was crystal absolutely after calcination at 1500℃. The ionic liquids slowed down the crystal changes of SiO₂.