Ionic liquids (ILs) as green solvents for cellulose dissolution and fabrication of cellulose fibres for a sustainable textile industry
Desiree ADAMCZAK1, Boyan ILIEV1, Thomas J. S. SCHUBERT1, Antje OTA2, Daniel FÖRSTER3, Ronald BEYER2, Marc Philip VOCHT2, Frank HERMANUTZ2, Frank STIEMKE 1
1IoLiTec Ionic Liquids Technologies GmbH, Heilbronn, Germany
2German Institutes of Textile and Fibre Research (DITF), Denkendorf, Germany
3LightPulse, Stuttgart, Germany
In the past decade, the interest in environmentally friendly and sustainable products as well as clean fabrication processes has increased immensely. In this context, one of the biggest challenges is actually the reduction of microplastics. To achieve this goal, the use of biobased, renewable materials is among the most promising approaches. For example, cellulose-based materials have emerged a huge interest in the textile industry. Due to its plentiful resources, the fabrication of 100% biodegradable fibres could be established. To this date, many different cellulose-based materials such as micro filament fibres, cellulose/chitin blend fibres, precursors for carbon fibres, and all-cellulose composites could be evolved.[1,2]
To process cellulose the choice of an appropriate solvent is essential. In recent years, ionic liquids (IL) were deployed as sustainable solvents because of their interesting mix of properties: They can be designed to combine a low toxicity, low vapor pressure, high thermal and chemical stability, low melting points as well as miscibility with many other solvent systems. Furthermore, their physical properties can be easily tuned by modifying of the cation or anion.[2, 3]
Within the BMBF-funded research project “NextSpin” and in cooperation with German Institutes of Textile and Fibre Research (DITF) and the company LightPulse a novel IL-technology for spinning of 100% biodegradable cellulose fibres were developed. Herein, an imidazolium-based alkanoate was identified to dissolve suitable amounts of cellulose. The chosen IL shows a high purity, a high thermal stability, a high polarity and a low sensitivity to hydrolysis. While the solution capacity (up to 12 w%) as well as the purity remains sufficient even at high recycling cycles, the darkening of the IL can influence the colour of the spun fibres. Thus, a feasible recycling method was developed to recover as well as discolourise the ionic liquid from IL + H2O systems in the cellulose spinning process. The applied IL-based processing of cellulose enables spinning of endless filaments with high absorbency, stretchability fineness and different geometries. This innovative IL-technology represents a promising environmentally friendly and sustainable alternative to the established viscose as well as Lyocell®-process to fabricate 100% biodegradable cellulose fibres.
 S.Acharya et al., Polymers 2021, 13,4344.
 F. Hermanutz et al., Macromol. Mater. Eng. 2019, 304, 1800450
 P. Wasserscheid, W. Keim, Angew. Chem. 2000, 39, 3772.