Dissolution, materialization and derivatization of chitin and chitosan in ionic liquids

Abstract

Chitin and chitosan are renewable biomass resources with macromolecular structures. Due to the strong intra-and inter-molecular hydrogen bonds, chitin and chitosan cannot be dissolved in water or traditional organic solvents, which tremendously limit their applications in many fields. Ionic liquid, as a novel green solvent, provides excellent solubility to chitin and chitosan. In this paper, the research progress on dissolution performance and dissolution mechanism of chitin and chitosan in ionic liquids is reviewed. Materials including fibers, films and gels created from the homogeneous solutions are summarized; meanwhile, the chemical derivatization of chitin and chitosan in ionic liquids are also discussed. Finally, the challenges and future development of ionic liquids in chitin and chitosan chemistry are proposed.

Rapid dissolution of chitin and chitosan with degree of deacetylation less than 80% in KOH/urea aqueous solution

“…[18][19][20] However, these solvents exhibit numerous limitations, such as, low solubility, high viscosity, rapid degradation, toxicity, and poor regenerated-material mechanical properties. Although ionic liquids and deep eutectic solvents dissolve chitin and chitosan on heating, [21][22][23][24][25][26] they are expensive, difficult to produce and recycle, and hazardous to human health and the environment. 27,28 In our previous work, LiOH/urea and NaOH/urea aqueous solutions dissolve cellulose by a hydrogen bond-induced dynamic self-assembly at low temperatures; [29][30][31] they have also been used for chitin and chitosan dissolution and the regeneration and functionalization of chitin-and chitosan-based materials.…”

“…18–20 However, these solvents exhibit numerous limitations, such as, low solubility, high viscosity, rapid degradation, toxicity, and poor regenerated-material mechanical properties. Although ionic liquids and deep eutectic solvents dissolve chitin and chitosan on heating, 21–26 they are expensive, difficult to produce and recycle, and hazardous to human health and the environment. 27,28…”

A highly stretchable and sensitive carboxymethyl chitosan-based hydrogel for flexible strain sensors

“…32 In the current study, 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) is one of the most widely conductive agents for modifying CMCS hydrogels. 33 Yan 34 made an antifreeze ionic liquid conductive hydrogel. The conductivity of the hydrogel can reach 1.1 S m −1 .…”