By: Dr. Matthias Maase, Dr. Klemens Massonne, Dr. Eric Uerdingen, Dr. Uwe Vagt, Aldrich ChemFiles 2006, 6.9, 3.

Aldrich ChemFiles 2006, 6.9, 3.

Solutions of Cellulose in Ionic Liquids

Dr. Matthias Maase, Dr. Klemens Massonne, Dr. Eric Uerdingen, Dr. Uwe Vagt, BASF Aktiengesellschaft, 67056 Ludwigshafen, Germany, www.basionics.com

At an estimated volume of ~700 billion tons, cellulose is the earth’s most widespread natural organic substance, making it an important biorenewable resource. Of the 40 billion tons nature renews every year, only 0.2 billion tons are used as feedstock for further processing.

Intensive exploitation of cellulose as a biorenewable feedstock has to date been prevented by the lack of a suitable solvent that can be used in the chemical processes. Robin Rogers and co-workers at the University of Alabama have found that solutions of cellulose can now be produced for the first time at useful concentrations using ionic liquids as solvents.1 This new technology opens up substantial potential for cellulose processing and manufacturing of new cellulose-based materials.

Currently, making cellulose fiber by the dissolving pulp method requires the use, and subsequent disposal of, tremendous volumes of various chemical additives. Approximately 600,000 metric tons of carbon disulfide (CS2) are consumed each year for this application. For each ton of cellulose fiber produced, there are more than two tons of waste substances. During the process, major volumes of waste water are produced that must be treated. These processes can be greatly simplified by the use of ionic liquid solvents, which are nearly entirely recycled. This can clearly reduce the amount of auxiliaries needed (Figure 1).

Figure 1: Current viscose process2 compared to an ionic liquid-based solvent process. The new ionic liquid process does not need CS2 as an auxiliary and offers the potential to significantly decrease the waste-per-ton cellulose fiber produced.

BASF and the Institute for Textile Chemistry and Chemical Fibers (ITCF) in Denkendorf are jointly investigating the properties of fibers spun from an ionic liquid solution of cellulose in pilot plant manufacturing. The fibers obtained show a smooth surface with a circular cross-section (Figure 2).

Figure 2: SEM micrographs of cellulose fibers spun from an ionic liquid solution.

Partnering with the University of Alabama, BASF has licensed the exclusive use of various ionic liquid technologies in the field of dissolution and processing of cellulose.3 BASF intends to tap the potential of this fascinating application fast and purposefully in cooperations together with customers and research partners.4

Cellulose in ionic liquids gives real physical solutions. The crystallinity of the cellulosic raw material fully disappears on dissolving it in the ionic liquid. BASIONIC™ BC 01 can dissolve up to 25 wt % of cellulose. The cellulose solutions show excellent long-term stability even at elevated temperatures without a significant decrease of the average degree of polymerization (DP). They do not contain gel particles and are air-stable.

BASF has now launched a series of solutions of cellulose in ionic liquids under the brand name CELLIONIC™. These are 5 wt % solutions of cellulose in EMIM acetate (BASIONIC™ BC 01) with cellulose of different DPs. The celluloses used in the CELLIONICs™ cover DPs of approximately 350, 680, and 1100. The cellulose raw material is provided by the Cellulose Fibers Business of Weyerhaeuser Company. Lab-scale quantities (100 g and 1 kg packages) will be available from Sigma-Aldrich in early 2007.

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  1. WO 2003 029329; Swatloski, R. P.; Spear, S. K.; Holbrey, J. D.; Rogers, R. D. J. Am. Chem. Soc. 2002, 124, 4974.
  2. Albrecht, W.; Külter, H.; Wulfhorst, B. Chemiefasern/Textilindustrie 1990, 92, 1046.
  3. BASF press release, P-05-519, November 14, 2005.
  4. BASF press release, P-06-367, August 29, 2006.

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