Structure and properties of the cellulose fibres spun from imidazolium-based carboxylate functionalized zwitterionic liquid

Dissolution of cellulose without further derivatization has been an active area of research in recent years. There are still challenges in developing a commercially viable solvent system for the dissolution and regeneration of cellulose as films and fibres. We report here a process for making cellulose fibres through the dry-jet wet spinning method by utilizing aqueous zwitterionic liquid (ZIL), viz., (6-(1-(2-methoxyethyl) imidazol-3-io)-hexanoate), in which oxyethylene substituted imidazolium-based cation and a carboxylate anion is covalently tethered. Our results suggest that 11 % ZIL dope could be successfully prepared and spun under industrially viable process conditions. The resultant fibres have properties comparable to that of commercial-grade Lyocell fibres. Particularly, the cellulose fibres spun from a cellulose ZIL solution exhibited a denier of 1.2-1.6, a tenacity of 3.5-4.0 g per denier (gpd), and an elongation at break of 8-10 %, which is comparable to cellulose fibres produced using ionic liquid and N-methyl-morpholine-N-oxide (NMMO) solvent. Cellulose fibres obtained from zwitterionic liquid have a crystallinity of 60 %, which is comparable to Lyocell fibres. To the best of our knowledge, this is the first report to demonstrate the successful spinning of regenerated cellulose fibres using zwitterionic liquids with mechanical properties comparable to commercial Lyocell fibres.