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

Hedlund, Artur ; Köhnke, Tobias ; Hagman, Joel LU ; Olsson, Ulf LU and Theliander, Hans (2019) In Cellulose 26(3). p.1545-1563
Abstract

Abstract: 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 ([C2mim][OAc]), and a co-solvent, dimethylsulfoxide (DMSO), are used to dissolve microcrystalline cellulose in concentrations from 5 to 25 wt%. The solutions are coagulated in water or 2-propanol (2PrOH). The coagulated material is then washed and solvent exchanged (water → 2PrOH → butanone → cyclohexane) in order to preserve the generated microstructures upon subsequent drying before analysis. Sweep... (More)

Abstract: 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 ([C2mim][OAc]), and a co-solvent, dimethylsulfoxide (DMSO), are used to dissolve microcrystalline cellulose in concentrations from 5 to 25 wt%. The solutions are coagulated in water or 2-propanol (2PrOH). The coagulated material is then washed and solvent exchanged (water → 2PrOH → butanone → cyclohexane) in order to preserve the generated microstructures upon subsequent drying before analysis. Sweep electron microscopy images of 50 k 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. Graphical abstract: [Figure not available: see fulltext.].

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Cellulose, Co-solvent, Ionic liquid, Microstructure, Non-solvent, Regeneration
in
Cellulose
volume
26
issue
3
pages
1545 - 1563
publisher
Springer
external identifiers
  • scopus:85058662143
ISSN
0969-0239
DOI
10.1007/s10570-018-2168-6
language
English
LU publication?
yes
id
275fbc1b-2bfa-4dfb-a02b-563cb55fa696
date added to LUP
2019-01-10 08:57:01
date last changed
2019-12-03 01:58:27
@article{275fbc1b-2bfa-4dfb-a02b-563cb55fa696,
  abstract     = {<p>Abstract: 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<sub>2</sub>mim][OAc]), and a co-solvent, dimethylsulfoxide (DMSO), are used to dissolve microcrystalline cellulose in concentrations from 5 to 25 wt%. The solutions are coagulated in water or 2-propanol (2PrOH). The coagulated material is then washed and solvent exchanged (water → 2PrOH → butanone → cyclohexane) in order to preserve the generated microstructures upon subsequent drying before analysis. Sweep electron microscopy images of 50 k 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. Graphical abstract: [Figure not available: see fulltext.].</p>},
  author       = {Hedlund, Artur and Köhnke, Tobias and Hagman, Joel and Olsson, Ulf and Theliander, Hans},
  issn         = {0969-0239},
  language     = {eng},
  number       = {3},
  pages        = {1545--1563},
  publisher    = {Springer},
  series       = {Cellulose},
  title        = {Microstructures of cellulose coagulated in water and alcohols from 1-ethyl-3-methylimidazolium acetate : contrasting coagulation mechanisms},
  url          = {http://dx.doi.org/10.1007/s10570-018-2168-6},
  doi          = {10.1007/s10570-018-2168-6},
  volume       = {26},
  year         = {2019},
}