木质纤维素气凝胶在离子液体中的制备及表征

Preparation and Characterization of Lignocellulose Aerogel in Ionic Liquid

为制备一种新型的木质基新材料,采用离子液体将木粉溶解,经循环冻融工艺处理结合临界点干燥即得木质纤维素气凝胶。采用扫描电镜(SEM)、透射电镜(TEM)和X射线衍射仪(XRD)对制备的木质纤维素气凝胶的微观形貌和结晶特性进行分析表征。结果表明,制备出的木质纤维素气凝胶具有的三维纤丝网状结构,通过冻融循环可以逐渐增强为片状结构,纳米纤丝的网络支架影响了气凝胶的多层级微米-纳米形貌;木质纤维素气凝胶的结晶度随冻融次数的增加呈先增加后减小的变化趋势;并阐释分析了木质纤维素气凝胶的形成机理。

To prepare a novel wood-based material, wood powder without any pre-treatment was dissolved in ionic liquid. With a circulated freezing-thawing procedure and critical point drying method, lignocellulose aerogel was successfully prepared. Morphological features and crystalline characteristics of the as-prepared material were characterized by field emission electron microscopy （SEM）, transmission electron microscope, and X-ray diffraction （XRD）. The results showed that the prepared lignocellulose aerogel possesses a three-dimensional structure of open fibrillar network and other novel nanostructure cellulose materials. The structure of the aerogels can be tuned from nanofibrillar to sheet-like skeletons with hierarchical micro- and nanoscale morphology by modifying the freeze- thaw cycles. The crystallinity first increased and then decreased along with increase of the freezing-thawing times. The formation mechanism of the lignocellulose aerogel was also discussed in this paper.