Preparation of Functional Ion Gels of Polysaccharides with Ionic Liquids pp. 455-466
Authors: (Jun-ichi Kadokawa, Graduate School of Science and Engineering, Kagoshima University, Japan)
Abstract: Ionic liquids, which are low-melting point salts and form liquids at room temperature or the temperatures below the boiling point of water, have recently received significant attention as the solvents in a wide range of the research fields, such as separation and
reaction media. Ionic liquids have been used as good solvents for natural polysaccharides such as cellulose and chitin. This chapter describes the preparation of functional ion gels of the polysaccharides with ionic liquids, which include the ionic liquids as the disperse media in the polysaccharide network matrixes. When the cellulose solution in an ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl) was left standing at room
temperature for 7 days, it gradually became the gel form. The resulting ion gel was characterized by the elemental analysis, TGA, and XRD measurements, which suggested that the gel was obtained by formation of the cellulose aggregates as cross-linking points in the solution owing to gradually absorbing water into the solution. This gelling technique was extended to provide ion gels of cellulose/starch and cellulose/chitin composite systems. Furthermore, the preparation of ion gels of hydrocolloid polysaccharides, such as carrageenan, xanthan gum, and guar gum, with BMIMCl was also achieved. The resulting ion gels exhibited specific unique and high performance properties.