Probing the Physical Properties, Synthesis and Cellulose Dissolution Ability of Dialkyl Phosphate Ionic Liquids

GRAPHICAL ABSTRACT

Abstract

We report the synthesis, characterization and cellulose dissolution properties of a series of ionic liquids bearing alkyl and hydroxyl-functionalized imidazolium and pyrrolidinium cations, and dialkyl phosphate anions. Ionic liquids that dissolve cellulose have anions that are excellent hydrogen bond acceptors. Based on this study, it is clear that the cation also plays a role. Cellulose dissolution was achieved in the imidazolium ionic liquids but not in the pyrrolidinium ionic liquids. Thermogravimetric analysis results show that most of the ILs are thermally stable up to 240 °C and thus are more suitable solvents for high temperature applications than most organic solvents. Imidazolium ILs are less viscous and slightly more thermally stable than the pyrrolidinium ILs of the same chain length.

Keywords:

• Dialkyl phosphate
• cellulose
• ionic liquid