Microstructures of cellulose coagulated in water and alcohols from 1-ethyl-3-methylimidazolium acetate: contrasting coagulation mechanisms
Journal article, 2019

Coagulation of cellulose solutions is a process whereby many useful materials with variable microstructures and properties can be produced. This study investigates the complexity of the phase separation that generates the structural heterogeneity of such materials. The ionic liquid, 1-ethyl-3-methylimidazolium acetate ([C(2)mim][OAc]), and a co-solvent, dimethylsulfoxide (DMSO), are used to dissolve microcrystalline cellulose in concentrations from 5 to 25wt%. The solutions are coagulated in water or 2-propanol (2PrOH). The coagulated material is then washed and solvent exchanged (water2PrOHbutanonecyclohexane) in order to preserve the generated microstructures upon subsequent drying before analysis. Sweep electron microscopy images of 50k magnification reveal open-pore fibrillar structures. The crystalline constituents of those fibrils are estimated using wide-angle X-ray spectroscopy and specific surface area data. It is found that the crystalline order or crystallite size is reduced by an increase in cellulose concentration, by the use of the co-solvent DMSO, or by the use of 2PrOH instead of water as the coagulant. Because previous theories cannot explain these trends, an alternative explanation is presented here focused on solid-liquid versus liquid-liquid phase separations. [GRAPHICS] .

Ionic liquid

Co-solvent

Microstructure

Regeneration

Non-solvent

Cellulose

Author

Artur Hedlund

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Swerea

Tobias Kohnke

Swerea

Joel Hagman

Lund University

Ulf Olsson

Lund University

Hans Theliander

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Wallenberg Wood Science Center (WWSC)

Cellulose

0969-0239 (ISSN) 1572882x (eISSN)

Vol. 26 3 1545-1563

Subject Categories

Inorganic Chemistry

Physical Chemistry

Other Chemistry Topics

DOI

10.1007/s10570-018-2168-6

More information

Latest update

2/23/2021