title: Nano-Structural Investigation on Cellulose Highly Dissolved in Ionic Liquid: A Small Angle X-ray Scattering Study.
abstract: We investigated nano-structural changes of cellulose dissolved in 1-ethyl-3-methylimidazolium acetate-an ionic liquid (IL)-using a small angle X-ray scattering (SAXS) technique over the entire concentration range (0-100 mol %). Fibril structures of cellulose disappeared at 40 mol % of cellulose, which is a significantly higher concentration than the maximum concentration of dissolution (24-28 mol %) previously determined in this IL. This behavior is explained by the presence of the anion bridging, whereby an anion prefers to interact with multiple OH groups of different cellulose molecules at high concentrations, discovered in our recent work. Furthermore, we observed the emergence of two aggregated nano-structures in the concentration range of 30-80 mol %. The diameter of one structure was 12-20 nm, dependent on concentration, which is ascribed to cellulose chain entanglement. In contrast, the other with 4.1 nm diameter exhibited concentration independence and is reminiscent of a cellulose microfibril, reflecting the occurrence of nanofibrillation. These results contribute to an understanding of the dissolution mechanism of cellulose in ILs. Finally, we unexpectedly proposed a novel cellulose/IL composite: the cellulose/IL mixtures of 30-50 mol % that possess liquid crystallinity are sufficiently hard to be moldable.
authors.affiliation: Faculty of Natural System, Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan. tkendo@staff.kanazawa-u.ac.jp.
authors.forename: Takatsugu
authors.initials: T
authors.lastname: Endo
authors.affiliation: Faculty of Natural System, Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan. hsmst14@gmail.com.
authors.forename: Shota
authors.initials: S
authors.lastname: Hosomi
authors.affiliation: Faculty of Natural System, Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan. fujii-sh091@stu.kanazawa-u.ac.jp.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Fujii
authors.affiliation: Institute for Frontier Science Initiative, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan. ninomiya@se.kanazawa-u.ac.jp.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Ninomiya
authors.affiliation: Faculty of Natural System, Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan. ktkenji@staff.kanazawa-u.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry; D010316:Particle Size; D053838:Scattering, Small Angle
chemical_list: D007093:Imidazoles; D052578:Ionic Liquids; D002482:Cellulose; C518739:1-ethyl-3-methylimidazolium
keywords: cellulose; composites; dissolution; ionic liquids; small angle X-ray scattering