Pyridinium-based ionic liquid/water mixture intended for efficient dissolution of cellulose, chitosan and chitin: The pivotal contribution of water

Abstract

An acidic ionic liquid (IL), i.e. 1-(carboxymethyl)pyridinium chloride, is synthesized and investigated for its untapped potential to dissolve cellulose, chitosan and chitin with concentrations of up to 11, 10 and 5 wt.%, respectively. Interestingly, the optimum water content of the IL/water towards efficient dissolution is determined to be as high as 40 wt.%, which is in evident contrast to the previous reports for other ILs by which the dissolution of polysaccharides is achieved at the expense of water content. Using high water content in IL/water mixture makes a breakthrough in ease of solution processability and dissolution cost reduction. Regenerated cellulose and chitosan have less crystallinity and lower temperature of thermal degradation onset (Tons) compared to the initial samples. The regenerated cellulose exhibits reduction in degree of polymerization, crystallinity and Tons by 55.1%, 11.0% and 38.2%, respectively. Chitin in addition to dissolution, is also hydrolyzed to quaternary ammonium chitosan.