title: Ionic liquid-mediated technology to produce cellulose nanocrystals directly from wood.
abstract: We report for the first time the direct extraction of cellulose nanocrystals (CNCs) from wood by means of a 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]) treatment. A native cellulosic product could be recovered in 44% yield with respect to wood cellulose content. The product was analyzed for morphological (TEM, AFM, XRD), chemical (FTIR, (13)C CP/MAS NMR), thermal (DSC, TGA) and surface properties (Zeta potential, contact angle). These analyses evidenced the presence of partially acetylated (surface DS=0.28) nanocrystals of native cellulose I microstructure, with a crystallinity index of about 75% and aspect ratio of 65. Direct production of CNCs from wood is ascribed to the simultaneous capability of [EMIM][OAc] to (1) dissolve lignin in situ while only swelling cellulose, (2) decrease intermolecular cohesion in wood via acetylation, and (3) to catalyze cellulose hydrolysis.
authors.affiliation: Chair of Forest Biomaterials, University of Freiburg, Werthmannstr. 6, 79085 Freiburg, Germany; Freiburg Materials Research Center, University of Freiburg, Stefan-Meier-Str. 21, 79104 Freiburg, Germany. Electronic address: hatem.abushammala@biomat.uni-freiburg.de.
authors.forename: Hatem
authors.initials: H
authors.lastname: Abushammala
authors.affiliation: Freiburg Materials Research Center, University of Freiburg, Stefan-Meier-Str. 21, 79104 Freiburg, Germany; Institute of Inorganic and Analytical Chemistry, University of Freiburg, Albertstr. 21, 79104 Freiburg, Germany. Electronic address: krossing@uni-freiburg.de.
authors.forename: Ingo
authors.initials: I
authors.lastname: Krossing
authors.affiliation: Chair of Forest Biomaterials, University of Freiburg, Werthmannstr. 6, 79085 Freiburg, Germany; Freiburg Materials Research Center, University of Freiburg, Stefan-Meier-Str. 21, 79104 Freiburg, Germany. Electronic address: marie-pierre.laborie@biomat.uni-freiburg.de.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Laborie
keywords: Cellulose nanocrystals; Hydrolysis; Ionic liquids; Wood pulping