Microstructures of cellulose coagulated in water and alcohols from 1-ethyl-3-methylimidazolium acetate: contrasting coagulation mechanismsShow others and affiliations
2019 (English)In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 3, p. 1545-1563Article in journal (Refereed) Published
Abstract [en]
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.].
Place, publisher, year, edition, pages
2019. Vol. 26, no 3, p. 1545-1563
Keywords [en]
Cellulose, Co-solvent, Ionic liquid, Microstructure, Non-solvent, Regeneration, Coagulation, Crystallite size, Ionic liquids, Ketones, Phase separation, Praseodymium compounds, Solvents, X ray spectroscopy, 1-ethyl-3-methylimidazolium acetates, Cosolvents, Electron microscopy images, Micro-crystalline cellulose, Microstructures and properties, Non-solvents, Structural heterogeneity
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:ri:diva-36913DOI: 10.1007/s10570-018-2168-6Scopus ID: 2-s2.0-85058662143OAI: oai:DiVA.org:ri-36913DiVA, id: diva2:1274183
2018-12-282018-12-282023-06-08Bibliographically approved