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Ionic Liquids For Cellulose Dissolution

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Ionic Liquids For Cellulose Dissolution

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Cellulose is a type of biodegradable natural polymer material, produced at a rate of 1.5×1012 t/year [1]. It has many fascinating properties, such as renewability, inexhaustibility, and biodegradability. Cellulose has been considered as a future sustainable feedstock of energy and chemical engineering at present. However, it is difficult to be dissolved in water and common organic solvents due to the strong inter- and intra-molecular hydrogen bonds. The traditional solvents have disadvantages such as toxicity, poor stability, and difficulty in recycling. Thus searching for a new green solvent has become a hot but difficult point in cellulose development. Ionic liquid is a new green solvent, which can dissolve cellulose, keratin and many other biomacromolecules under certain conditions. The emergence of ionic liquids provides an environmentally friendly and biodegradable solvent system for cellulose dissolution, which has a wide development prospection [2].

Ionic Liquids For Cellulose Dissolution

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The most representative ionic liquids system used for cellulose dissolution can be classified into imidazole ionic liquids, morpholine ionic liquids and pyridine ionic liquids.

The most representative ionic liquids system used for cellulose dissolution can be classified into imidazole ionic liquids, morpholine ionic liquids and pyridine ionic liquids.

  • Imidazole ionic liquids for cellulose dissolution

Imidazole ionic liquids are the most common ionic liquids used for cellulose dissolution. A study group synthesized a novel ionic liquid, 1-allyl-3-methylimidazolium chloride (AMIMCl). They found that the solubility of cellulose in AMIMCl was temperature dependent. AMIMCl only swelled cellulose but could not dissolve it at room temperature. However, cellulose dissolved readily in AMIMCl at 60 °C with stirring. Cellulose dissolved more rapidly with increasing temperature. A cellulose/AMIMCl solution of 5 wt % concentration was obtained only within 30 min at 80 °C [3].

  • Morpholine ionic liquids for cellulose dissolution

With the progress of technology, some research groups reported the N-allyl-N-methylmorpholinium acetate ([AMMorp][OAc]) ionic liquid system. [AMMorp][OAc] was found to dissolve cellulose easily without any pretreatment of natural cellulose. At 120 °C, [AMMorp][OAc] could dissolve 25 wt%, 28 wt% and 30 wt% of cellulose with degree of polymerization—2082, 1644 and 789 respectively, in 20 min [4].

  • Pyridine ionic liquids for cellulose dissolution

The use of pyridine ionic liquids in cellulose dissolution is one of the most studied systems in recent years. A group of researchers synthesized N-Allylpyridinium chloride ([APy]Cl) ionic liquid by one-step process. It is found that [APy]Cl ionic liquid is a good solvent for cellulose. The solubility of cotton pulp cellulose and absorbent cotton fiber is up to 19.71% and 15.29% in ionic liquid at 120 °C, respectively [5].

Ionic Liquids For Cellulose DissolutionFigure 1. Polarizing microscope images of cotton pulp cellulose dissolved in [APy]Cl for (a) 0 min, (b) 5 min, (c) 10 min, (d) 15 min [5].

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Alfa Chemistry has a profound research foundation in terms of cellulose dissolution, and at our company you can find the appropriate ionic liquid for cellulose dissolution. Alfa Chemistry will serve you with the most abundant experience and affordable prices. If you have any problems, we will provide technical support for you. Please don't hesitate to contact us.

References

  • Klemm, D.; et al. Cellulose: fascinating biopolymer and sustainable raw material. Angewandte Chemie (International ed. in English). 2005, 44(22): 3358-3393.
  • Xie, Y.; et al. Study on dissolving cellulose by ionic liquids. Chemistry Bulletin. 2020, 83(12): 1104-1112.
  • Zhang, H.; et al. 1-Allyl-3-methylimidazolium chloride room temperature ionic liquid: a new and powerful nonderivatizing solvent for cellulose. Macromolecules. 2005, 38(20): 8272-8277.
  • Raut, D. G.; et al. A morpholinium ionic liquid for cellulose dissolution. Carbohydrate Polymers. 2015, 130: 18-25.
  • Fu, L.; et al. Synthesis of pyridinium-based ionic liquid and its dissolubility of cellulose. Modern Chemical Industry. 2011, 31(9): 39-42.

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