Structure of cellulose/direct dye complex regenerated from supercritical water
Structure of cellulose/direct dye complex regenerated from supercritical water
复制标题
超临界水再生纤维素/直接染料复合物的结构
DOI：
10.1007/s10570-016-0900-7
复制
发表时间：
2016
期刊：
影响因子：
5.7
通讯作者：
Chihiro Yamane
中科院分区：
文献类型：
--
作者：
Hitomi Miyamoto;Yoshiaki Yuguchi;Dmitry M. Rein;Yachin Cohen;Kazuyoshi;Chihiro Yamane
通过小角和广角同步辐射X射线散射和低温透射电子显微镜研究了直接染料存在下纤维素从超临界水中的再生，以了解染料对纤维素结构形成的影响。此外，纤维素和直接染料之间的相互作用，其特征在于使用分子动力学模拟。在不含染料的从超临界水再生的纤维素的广角X射线衍射图中观察到对应于纤维素II晶体的峰，而在含有直接染料（直接红28或直接蓝1）的样品的衍射图中没有观察到这些峰。这一结果表明，直接染料阻止再生纤维素的结晶。分子动力学模拟的结果表明，葡萄糖环的平面与染料的芳香族部分相互作用，染料分子的磺酸根基团与纤维素的羟基相互作用。此外，葡萄糖环的CH基团和染料的芳族部分（例如，萘和联苯部分）每周相互作用。当纤维素从溶液中再生时，通过疏水相互作用形成的纤维素片结构作为初始结构出现。发现直接染料影响这种纤维素片结构的形成，因为纤维素分子溶解在超临界水中。在小角X射线散射的Kratky图中，在较小q（<0.5）的区域中清楚地观察到纤维素和纤维素/DR 28样品的峰，表明纳米级组装结构分散在这些系统中。在纤维素和纤维素/DR 28样品的上清液中观察到成束的片状和扭曲的带状结构。这些分散的结构被认为是纤维素结构形成的中间体。
The regeneration of cellulose from supercritical water in the presence of direct dyes was studied by small- and wide-angle synchrotron X-ray scattering and cryo-transmission electron microscopy to understand the effects of dyes on the structure formation of cellulose. In addition, the interactions between cellulose and the direct dyes were characterized using molecular dynamics simulations. Peaks corresponding to cellulose II crystals were observed in the wide-angle X-ray diffraction pattern of cellulose regenerated from supercritical water without dyes, whereas these peaks were not observed in the diffraction patterns of samples with direct dye (Direct Red 28 or Direct Blue 1). This result indicated that the direct dyes prevented the crystallization of regenerated cellulose. The results of the molecular dynamics simulations indicated that the planes of glucose rings interacted with the aromatic moieties of the dyes and that the sulfonate groups of the dye molecules interacted with the hydroxyl groups of cellulose. In addition, the CH groups of the glucose rings and aromatic moieties of the dyes (e.g., naphthalene and biphenyl moieties) interacted weekly. When cellulose regenerates from solution, cellulose sheet structures formed via hydrophobic interactions appear as the initial structure. The direct dyes were found to affect the formation of this cellulose sheet structure because cellulose molecularly dissolved in supercritical water. In the Kratky plots for small-angle X-ray scattering, a peak was clearly observed for the cellulose and cellulose/DR28 samples in the region of smaller q (<0.5), indicating that the nanoscale assembly structures dispersed in these systems. Bundled sheet-like and twisted ribbon-like structures were observed in the supernatants of the cellulose and cellulose/DR28 samples. These dispersed structures were considered to be intermediates in the structural formation of cellulose.