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Cellulose Amorphization by Swelling in Ionic Liquid/Water Mixtures: A Combined Macroscopic and Second‐Harmonic Microscopy Study
Author(s) -
Glas Daan,
Paesen Rik,
Depuydt Daphne,
Binnemans Koen,
Ameloot Marcel,
De Vos Dirk E.,
Ameloot Rob
Publication year - 2015
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201402776
Subject(s) - swelling , cellulose , ionic liquid , chemical engineering , materials science , ionic bonding , microscopy , chemistry , chemical physics , nanotechnology , composite material , organic chemistry , ion , optics , physics , catalysis , engineering
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.