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.
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.
Carbohydr Polym. 2015 Dec 10;134:609-16. doi: 10.1016/j.carbpol.2015.07.079. Epub 2015 Jul 26.
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.
我们首次报道了通过 1-乙基-3-甲基咪唑醋酸盐 ([EMIM][OAc]) 处理从木材中直接提取纤维素纳米晶体 (CNC)。相对于木材纤维素含量，可回收 44%的天然纤维素产物。对产物进行了形态学（TEM、AFM、XRD）、化学（FTIR、(13)C CP/MAS NMR）、热（DSC、TGA）和表面性质（Zeta 电位、接触角）分析。这些分析表明存在部分乙酰化（表面 DS=0.28）的具有天然纤维素 I 微观结构的纳米晶体，结晶度指数约为 75%，纵横比为 65。[EMIM][OAc] 能够（1）原位溶解木质素，同时仅溶胀纤维素，（2）通过乙酰化降低木材中分子间的内聚力，以及（3）催化纤维素水解，从而直接从木材中生产 CNC。
