Molecular dynamics simulation of dehydration in cellulose/water crystals
Molecular dynamics simulation of dehydration in cellulose/water crystals
复制标题
DOI：
10.1007/s10570-015-0716-x
复制
发表时间：
2015-07
期刊：
影响因子：
5.7
通讯作者：
H. Miyamoto;C. Yamane;K. Ueda
中科院分区：
文献类型：
--
作者：
H. Miyamoto;C. Yamane;K. Ueda
众所周知，纤维素/水复合物有两种晶体类型：Na-纤维素IV和纤维素II水合物。这些晶体中的水分子随着温度的升高而释放，然后将水合模型转化为纤维素II晶体。甚至当纤维素/水晶体浸泡在水中时也可以观察到脱水。在这项研究中，我们研究了钠-纤维素IV和纤维素II水合物的脱水过程中使用分子动力学模拟。在这两种晶体中，随着模拟时间的推移，水分子逐渐从晶体中释放出来，同时与纤维素的羟基形成氢键。有趣的是，水分子从疏水相互作用形成的分子片之间的空间释放出来。所有的羟基都存在于分子片的表面。因此，有理由认为水分子在两层之间通过。对于Na-纤维素IV，gt构象的比例很高。此外，观察到水分子在模拟过程中在每个相邻分子片上的O 6和O3之间的空间中形成氢键。另一方面，由于O 6···O 6分子间氢键的存在，在纤维素II水合物中主要观察到gg构象。在模拟过程中，水分子存在于O2和O3之间的空间中，同时形成氢键。
It is well known that there are two crystal types for a cellulose/water complex: Na–cellulose IV and cellulose II hydrate. The water molecules in these crystals are released with increasing temperature and the hydrated models are then transformed into cellulose II crystals. Dehydration can be observed even when the cellulose/water crystal is soaked in water. In this study, we investigated the dehydration process in Na–cellulose IV and cellulose II hydrate using molecular dynamics simulations. In both crystals, as simulation time progressed, the water molecules were gradually released from the crystal while forming hydrogen bonds with the hydroxyl groups of cellulose. Interestingly, water molecules were released from the spaces between the molecular sheets formed by hydrophobic interactions. All hydroxyl groups existed on the surface of the molecular sheets. Therefore, it is reasonable to suggest that water molecules pass between the sheets. For Na–cellulose IV, the ratio ofgtconformations was high. In addition, it was observed that water molecules were in the space between O6 and O3 on each adjacent molecular sheet forming hydrogen bonds during simulation. On the other hand, theggconformations were mainly observed in cellulose II hydrate probably because of the presence of the O6···O6 intermolecular hydrogen bond. During the simulation, the water molecules were present in the space between O2 and O3 while forming hydrogen bonds.