title: Cellulose amorphization by swelling in ionic liquid/water mixtures: a combined macroscopic and second-harmonic microscopy study.
abstract: Amorphization of cellulose by swelling in ionic liquid (IL)/water mixtures at room temperature is a suitable alternative to the dissolution-precipitation pretreatment known to facilitate enzymatic digestion. When soaking microcrystalline cellulose in the IL 1-ethyl-3-methylimidazolium acetate containing 20 wt % water, the crystallinity of the cellulose sample is strongly reduced. As less than 4 % of the cellulose dissolves in this mixture, this swelling method makes a precipitation step and subsequent energy-intensive IL purification redundant. Second-harmonic generation (SHG) microscopy is used as a structure-sensitive technique for in situ monitoring of the changes in cellulose crystallinity. Combined optical and SHG observations confirm that in the pure IL complete dissolution takes place, while swelling without dissolution in the optimal IL/water mixture yields a solid cellulose with a significantly reduced crystallinity in a single step.
authors.affiliation: Centre for Surface Chemistry and Catalysis, Department of Microbial and Molecular Systems, KU Leuven, Kasteelpark Arenberg 23, box 2461, 3001 Leuven (Belgium).
authors.forename: Daan
authors.initials: D
authors.lastname: Glas
authors.forename: Rik
authors.initials: R
authors.lastname: Paesen
authors.forename: Daphne
authors.initials: D
authors.lastname: Depuydt
authors.forename: Koen
authors.initials: K
authors.lastname: Binnemans
authors.forename: Marcel
authors.initials: M
authors.lastname: Ameloot
authors.forename: Dirk E
authors.initials: DE
authors.lastname: De Vos
authors.forename: Rob
authors.initials: R
authors.lastname: Ameloot
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D008853:Microscopy; D014867:Water / Q000737:chemistry*
chemical_list: D007093:Imidazoles; D052578:Ionic Liquids; D014867:Water; D002482:Cellulose; C518739:1-ethyl-3-methylimidazolium
keywords: biomass; cellulose; ionic liquids; spectroscopy; sustainable chemistry