Periodic disorder along ramie cellulose microfibrils
Periodic disorder along ramie cellulose microfibrils
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DOI：
10.1021/bm025772x
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发表时间：
2003-07-01
影响因子：
6.2
通讯作者：
Langan, P
中科院分区：
文献类型：
--
作者：
Nishiyama, Y;Kim, UJ;Langan, P
用中子小角散射法研究了苎麻和毛白杨纤维素纤维。不稳定的氢原子被氘原子取代，在水可访问的无序区域的纤维，以增加中子散射之间的对比度的无序和结晶区域。当从氢化和氘代的干苎麻纤维收集的散射被减去时，观察到对应于150 nm的纵向周期的双折射布拉格反射。没有布拉格反射观察到与棉木纤维，可能是因为较低的取向的微纤维在细胞壁中。然后对苎麻纤维进行了电子显微镜、酸水解、凝胶渗透色谱和粘度研究。水解样品的聚合度（LODP）的稳定性与衍射研究中观察到的周期性完全匹配。与LODP相关的重量损失仅为约1.5%，因此，可以认为微纤丝每300个残基具有4-5个无序残基。
Small angle neutron scattering studies have been carried out on cellulose fibers from ramie and Populus maximowicii (cotton wood). Labile hydrogen atoms were replaced by deuterium atoms, in water-accessible disordered regions of the fibers, to increase the neutron scattering contrast between the disordered and crystalline regions. A meridional Bragg reflection, corresponding to a longitudinal periodicity of 150 nm, was observed when scattering collected from hydrogenated and deuterated dry ramie fibers was subtracted. No Bragg reflection was observed with the cotton wood fibers, probably because of lower orientation of the microfibrils in the cell wall. The ramie fibers were then subjected to electron microscopy, acid hydrolysis, gel permeation chromatography, and viscosity studies. The leveling off degree of polymerization (LODP) of the hydrolyzed samples matched exactly the periodicity observed in the diffraction studies. The weight loss related to the LODP was only about 1.5%, and thus, the microfibrils can be considered to have 4-5 disordered residues every 300 residues.