Crystal transition from cellulose II hydrate to cellulose II
Crystal transition from cellulose II hydrate to cellulose II
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DOI：
10.1016/j.carbpol.2011.05.050
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发表时间：
2011-08-15
影响因子：
11.2
通讯作者：
Wada, Masahisa
中科院分区：
文献类型：
--
作者：
Kobayashi, Kayoko;Kimura, Satoshi;Wada, Masahisa
通过将丝光纤维素II浸入无水肼中，然后用水洗涤来制备纤维素II水合物的样品。同步加速器X-射线纤维衍射和固态C-13 NMR测量表明，纤维素II水合物具有较大的晶胞，其中含有结晶度较低的水分子比丝光纤维素II。但它具有与丝光纤维素II基本相同的分子构象。在受控的相对湿度下，使用同步加速器X-射线衍射监测从纤维素II水合物到纤维素II的晶体转变。在干燥过程中，纤维素II水合物逐渐收缩，这减小了分子链的疏水堆叠片之间的距离，同时保持其片结构。没有一个明显的过渡点和过渡的不可逆性表明，在纤维素II水合物的晶胞中发生的水分子的随机位置。在热水中退火样品时，纤维素II水合物转化为纤维素II。纤维素II水合物在高温下不稳定，即使在水中也是如此。(C)2011爱思唯尔有限公司版权所有。
Samples of cellulose II hydrate were prepared by immersion of mercerized cellulose II in anhydrous hydrazine followed by washing with water. The synchrotron X-ray fiber diffraction and solid-state C-13 NMR measurements showed that cellulose II hydrate had a larger unit cell that contained water molecules with lower degree of crystallinity than mercerized cellulose II. but it had basically the same molecular conformation as mercerized cellulose II. The crystal transition from cellulose II hydrate to cellulose II was monitored using synchrotron X-ray diffraction under controlled relative humidity. In the drying process, the cellulose II hydrate gradually contracted, and this decreased the distance between the hydrophobic stacking sheets of molecular chains, while maintaining its sheet structure. The absence of an obvious transition point and the irreversibility of the transition indicated a random location of the water molecules occurred in the unit cell of cellulose II hydrate. On annealing a sample in hot water, the cellulose II hydrate was converted to cellulose II. Cellulose II hydrate was unstable at high temperatures, even in water. (C) 2011 Elsevier Ltd. All rights reserved.