Chapter 2 - Processing techniques of chitin-based gels, blends, and composites using ionic liquids

Abstract

Chitin is widely distributed in nature, and thus is a very important biomass resource. However, it is mostly unutilized because of its poor solubility and processability. Because ionic liquids have been identified as good solvents for natural polysaccharides, this chapter presents the research on processing techniques of chitin-based blend and composite materials through dissolution and gelation with ionic liquids. In the past decade, some imidazolium acetates and alkanoates have been reported to dissolve chitin. The author also found that 1-allyl-3-methylimidazolium bromide (AMIMBr) dissolves chitin. The ionic liquid also forms an ion gel with chitin at higher contents. Chitin/cellulose binary ion gel and film were obtained from the individually prepared polysaccharide solutions with ionic liquids. The binary ion gel was applied as a novel electrolyte for an electric double layer capacitor. Efficient approaches, including regeneration and extrusion processes, for blending and compositing chitin with other polymers in ionic liquids media have been also developed. Self-assembled chitin nanofibers were fabricated in a dispersion obtained by regeneration from the chitin ion gel with AMIMBr using methanol, which formed a film by subjecting the dispersion to filtration. The self-assembled chitin nanofibers have been used as a reinforcing agent for other polymers, such as cellulose derivatives and natural rubber to produce composite films. Surface-initiated graft polymerization of some monomers from initiating sites present on the self-assembled chitin nanofibers has been also investigated.