The Crystallinity of Nanocellulose: Dispersion-Induced Disordering of the Grain Boundary in Biologically Structured Cellulose
The Crystallinity of Nanocellulose: Dispersion-Induced Disordering of the Grain Boundary in Biologically Structured Cellulose
复制标题
DOI：
10.1021/acsanm.8b01438
复制
发表时间：
2018-10-01
影响因子：
5.9
通讯作者：
Isogai, Akira
中科院分区：
文献类型：
--
作者：
Daicho, Kazuho;Saito, Tsuguyuki;Isogai, Akira
在树木中，几纳米宽的纤维素结晶原纤维与其他生物聚合物（如木质素和半纤维素）紧密结合，形成坚固的细胞壁。纤维素纳米纤维（CNF）是通过对细胞壁纤维素进行纯化、改性和崩解等连续处理而获得的。在这里，我们报告的结晶CNFs是由成束的纤维素原纤维之间的界面。当去除半纤维素后原纤维更密集地成束时，单个原纤维的界面或表面处的纤维素分子是有序的。反过来，当成束的原纤维在崩解为CNF时分散时，界面分子变得无序。分散的原纤维的形态分析支持一个模型，其中单纤维素原纤维在树木是由18个分子链。考虑到18链模型，通过NMR分析，分散的原纤的表面分子在碳原子构象中是无序的，而所有18个链在分子片堆叠中是完全有序的以吸收X射线。
In trees, a-few-nanometers-wide crystalline fibrils of cellulose are tightly bundled with other biopolymers, such as lignin and hemicelluloses, to form robust cell walls. Cellulose nanofibers (CNFs) are obtained by successive treatments including the purification, modification, and disintegration of cell-wall cellulose. Herein, we report that the crystallinity of CNFs is governed by the interface between the bundled cellulose fibrils. The cellulose molecules at the interface or at the surface of the individual fibrils are ordered when the fibrils are more densely bundled upon removal of hemicelluloses. In turn, the interfacial molecules become disordered when bundled fibrils disperse upon disintegration as CNFs. Morphological analysis of the dispersed fibrils supports a model where single-cellulose fibrils in trees are composed of 18 molecular chains. Considering the 18-chain model, the surface molecules of the dispersed fibrils are disordered in the conformation of carbon atoms as analyzed by NMR, while all of the 18 chains are fully ordered in molecular sheet stacking to diffract X-rays.