IONCELL-F technology developed at Aalto University in collaboration with the University of Helsinki converts wood into textiles without any harmful chemicals. It is an environmentally friendly alternative to the water-intensive cotton production. In addition, the process may revolutionize the recycling of textile waste, as waste cotton can get a new life as high-quality luxury fibers.


What is IONCELL-F?

IONCELL-F is a new technology for producing man-made cellulosic textile fibers. IONCELL-F process is developed at Aalto University by the researchs of Prof. Herbert Sixta's group, and it uses a novel solvent, ionic liquid 1,5-diazabicyclo[4.3.0]non-5-ene acetate (or shortly [DBNH][OAc]) invented at University of Helsinki by Prof. Ilkka Kilpeläinen's group.


Demand for textile fibers is rapidly increasing because of the population growth and an improved standard of living. The future demand for textiles cannot be met by increasing the production of  cotton due to the large land area required for farming and the amount of water required for irrigation. Therefore, sustainable man-made fibers are needed to substitute cotton. 

Currently, there are two main man-made cellulose fibers (MMCF) on the market: viscose and lyocell (Tencel®). Production of viscose requires the use of carbon disulfide, a very toxic chemical. The solvent applied in the production of Tencel® fibers, NMMO, also has an intrinsic shortcoming: its chemical and thermal instability, causing a risk of dangerous runaway reactions.

The ionic liquid used in the IONCELL-F process is an environmentally friendly and inherently safe alternative to the solvents used in current man-made cellulosic fiber production processes.

Raw materials

The most common cellulose feedstocks for production of man-made cellulosic fibers is dissolving pulp. In addition to dissolving pulp, IONCELL-F process can utilize paper grade pulp from the kraft pulping process, as well as waste paper and cardboard, or waste cotton.

Ionic liquids

Ionic liquids are salts that have a melting point below 100 °C. The cellulose dissolving capability of ionic liquids has been known since 1930's, but the dissolution mechanism is still not fully understood. Of the numerous different ionic liquids tested over the years, [DBNH][OAc] was found to have excellent properties for the fiber spinning.

Properties of IONCELL-F fibers

IONCELL-F fibers feel soft and are strong even when wet. The fiber properties of IONCELL-F are equal or better than present viscose and Tencel®-fibers. Because of their high tenacity, IONCELL-F fibers are also promising for technical applications, e.g. for composites.

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IONCELL-F process

IONCELL-F fibers are produced using a Lyocell-type spinning process. There are three main steps in the fiber production process: cellulose dissolution, fiber spinning and recovery of the solvent.

Kneader (Photo: Anni Hanén)

Cellulose is dissolved into ionic liquid in a vertical kneader.

Dissolution of cellulose

IONCELL-F is based on the direct dissolution of cellulose. The direct dissolution reduces the number of process steps in comparison to e.g. viscose process, in which cellulose has to be first converted to a soluble derivative.

In the dissolution step, pulp is mixed with the ionic liquid. Due to the high viscosity of the  mixture, the mixing is carried out in a kneader reactor.

The resulting cellulose solution is called spinning dope. The dope is filtered to remove possible residual solids, and then used for fiber spinning.


Fiber spinning  

IONCELL-F fibers are produced using dry-jet wet spinning. In this spinning technique, the cellulose solution is extruded through a spinneret forming fluid filaments, which then pass through an air gap into a coagulation bath. The coagulation bath is filled with water, an anti-solvent, and thus cellulose is regenerated. The formed fiber filaments are collected for downstream processing.

The strength of the fibers arises from the use of air gap, in which the fluid filaments are stretched. Most of the orientation of the cellulose chains occurs at this stage, which affects the fiber properties.

The downstream processing of fibers includes cutting the filaments to staple fibers, opening of the fibers, washing and surface treatment. After that, the fibers can be converted into yarns by a yarn production process that includes carding and spinning.

Spinning of Ioncell-F fibers (Photo: Anni Hanén)

Dry-jet wet spinning.


Recovery of ionic liquid (Photo: Anni Hanén)

Recovery of ionic liquid using a thin-film evaporator.

Solvent recovery

For a sustainable process, it is necessary to have a closed solvent and water loop in the production of IONCELL-F.

During the fiber spinning, ionic liquid is dissolved in water in the spin bath, and will be recovered as an aqueous solution. The ionic liquid is then separated from water and purified to prevent accumulation of soluble impurities in the closed solvent loop.

The research on the recovery and purification of ionic liquid is currently on-going.


Watch the video to see all the steps of the IONCELL-F process.

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Prototype products

Designed by young talents of Aalto ARTS



The first  product made of IONCELL-F: a knitted scarf designed by Marjaana Tanttu.

Bow tie and handkerchief

IONCELL-F Bow tie and handkerchief (Photo: Eeva Suorlahti)

A woven bow tie and a handkerchief designed and made by Eveliina Netti.

From birch to catwalk - in collaboration with Marimekko®

Allu dress knitted from birch

The first IONCELL garment, a dress designed by Tuula Pöyhönen, was presented on the occasion of Marimekko®’s fashion show in Helsinki Central Railway Station’s ticket hall on March 13, 2014.

Wowen and printed

IONCELL-F fabric printed by Marimekko (Tiara by Erja Hirvi)

The printing properties of IONCELL-F fabric were tested in collaboration with Marimekko® in 2016. The print, Tiara, is designed by Erja Hirvi.

Inspired by the nature and waste

50 shades of lignin

Vivid, natural colors produced by using lignin as an additive in the production of IONCELL-F fibers.

Recycling textile waste

IONCELL-F in textile recycling - CHEMARTS2015 (Photo: Eeva Suorlahti)

Recycling of cotton waste using IONCELL-F. The original colors of the fabric can stay in the new fibres, which reduces the need of dyeing. Aalto CHEMARTS / Senja Smirnova.

IONCELL-F in composites

Phone cover

Cellphone case made of lignin IONCELL-F composite

A phone case made of a composite of IONCELL-F fibers and epoxy resin.


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  • Prof. Herbert Sixta
  • Michael Hummel, Staff Scientist
  • Shirin Asaadi, PhD candidate
  • Yibo Ma, PhD candidate
  • Sanna Hellstén, Postdoctoral researcher
  • Elsa Walger, Postdoctoral researcher
  • Simone Haslinger, PhD candidate
  • Harri Santamala, PhD candidate

The development of IONCELL-F is a very cross-disciplinary project. We work in a close collaboration with the designers (Aalto ARTS, the Fashion/Textile Futures research group, Prof. Kirsi Niinimäki), chemists (University of Helsinki, Laboratory of Organic Chemistry, Prof. Ilkka Kilpeläinen and Dr. Alistair King), chemical engineers (Aalto CHEM, Chemical Engineering research group, Prof. Ville Alopaeus), and textile engineers (Swedish School of Textiles at the University of Borås and Tampere University of Technology).

IONCELL-F publications

Scientific articles in peer-review journals


Michud, A.;  Hummel, M.; Sixta, H. 2016, Influence of process parameters on the structure formation of man-made cellulosic fibers from ionic liquid solution, Journal of Applied Polymer Science 133 (30): 43718.

Michud, A.; Tanttu, M.; Asaadi, S.; Ma, Y.; Netti, E.; Kääriainen, P.; Persson, A.; Berntsson, A.; Hummel, M.; Sixta, H. 2016, Ioncell-F: ionic liquid-based cellulosic textile fibers as an alternative to viscose and Lyocell, Textile Research Journal 86 (5): 543-552.

Hauru, L.K.J.; Hummel, M.; Nieminen, K.; Michud, A.; Sixta, H, 2016, Cellulose regeneration and spinnability from ionic liquids, Soft Matter 12 (5): 1487-1495.

Ma, Y.; Hummel, M.; Määttänen, M.; Särkilahti, A.; Harlin, A.; Sixta, H. 2016, Upcycling of waste paper and cardboard to textiles, Green Chemistry 18 (3): 858-866.


Ma, Y.; Asaadi, S.; Johansson, L.-S.; Ahvenainen, P.; Reza, M.; Alekhina, M.; Rautkari, L.; Michud, Anne; Hauru, L.; Hummel, M.; Sixta, H. 2015, High-Strength Composite Fibers from Cellulose-Lignin Blends Regenerated from Ionic Liquid Solution, ChemSusChem 8 (23): 4030-4039.

Sixta, H.; Michud, A.; Hauru, L.; Asaadi, S.; Ma, Y.; King, A.W.T.; Kilpeläinen, I.; Hummel, M. 2015, Ioncell-F: A High-strength regenerated cellulose fibre, Nordic pulp & paper research journal 30 (1): 43-57.

Michud, A.; Hummel, M.; Sixta, H. 2015, Influence of molar mass distribution on the final properties of fibers regenerated from cellulose dissolved in ionic liquid by dry-jet wet spinning, Polymer 75 (28 September 2015): 1-9.

Hummel, M.; Michud, A.; Tanttu, M.; Asaadi, S.; Ma, Y.; Hauru, L.K.J.; Parviainen, A.; King, A.W.T.; Kilpelainen, I.; Sixta, H. 2015, Ionic liquids for the production of man-made cellulosic fibers - opportunities and challenges, Advances in polymer science (24 April 2015): 1-36.

Hummel, M.; Michud, A.; Asaadi, S.; Ma, Y.; Sixta, H.; Tanttu, M.; Netti, E. 2015, High-tenacity textile cellulose fibers from ionic liquid solutions, Chemical Fibers International, 65 (2): 105-107.


Hauru, L.K.J.; Hummel, M.; Michud, A.; Sixta, H. 2014, Dry jet-wet spinning of strong cellulose filaments from ionic liquid solution, Cellulose, 21 (6), 4471-4481.


Hauru, L.K.J.;Hummel, M.;King, A.W.T.;Kilpeläinen, I.;Sixta, H. 2012, Role of solvent parameters in the regeneration of cellulose from ionic liquid solutions, Biomacromolecules 13 (9): 2896-2905.

Doctoral theses

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IONCELL-F in news and blogs

IONCELL-F in the TV series "Suomen tulevaisuus" in Spring 2016:

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Want to know more about IONCELL-F?

If you are interested to hear more about IONCELL-F, please contact us.

Contact information

Professor Herbert Sixta
Aalto University School of Chemical Technology
tel. +35850 3841764
herbert.sixta [at] aalto [dot] fi

Page content by: | Last updated: 21.12.2016.