Dynamics and conformations of PEO chains chemically bonded on silica: comparison between 1H and 2H NMR
Dynamics and conformations of PEO chains chemically bonded on silica: comparison between 1H and 2H NMR
复制标题
化学键合在二氧化硅上的 PEO 链的动力学和构象：1H 和 2H NMR 之间的比较
DOI：
10.1002/mrc.1997
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Hubert Hommel
中科院分区：
文献类型：
--
作者：
T. Tajouri;Hubert Hommel
利用核磁共振氢谱（1H NMR）研究了二氧化硅接枝聚环氧乙烷链层中单体单元的运动。首先，从现象学的角度定性地讨论了弛豫时间对接枝比的依赖关系。其次，在不同接枝率的相同样品中，观察了高速旋转对核磁共振谱线的收窄效应。魔角旋转技术允许确定每个接枝比的两个相关时间：快速运动环境的τc特征和慢运动环境的τl特征。此外，利用对分子运动各向异性敏感的氘核磁共振（2H NMR）研究了这些接枝链的动力学。研究了两种极端接枝率和每次接枝率随温度的变化。各向异性在低温和低接枝率下更为明显。结果与1H NMR弛豫时间随温度的变化规律一致。版权所有©2007 John Wiley & Sons， Ltd
1H NMR was used to study the motion of monomer units in a layer of poly(ethylene oxide) chains grafted on silica. First, the dependence of the relaxation times on the grafting ratios is discussed qualitatively from a phenomenological point of view. Next, the NMR line narrowing effect by high‐speed rotation is observed in the same samples with different grafting ratios. The magic angle spinning technique permits determination of two correlation times for each grafting ratio: τc characteristic of an environment with a fast motion and τl characteristic of an environment with a slow motion. In addition, the dynamics of these grafted chains are investigated by deuterium NMR (2H NMR), which is sensitive to the anisotropy of molecular motion. The evolution has been studied for two extreme grafting ratios and each time as a function of temperature. The anisotropy is more marked at low temperatures and for a low grafting ratio. The results are consistent with the 1H NMR relaxation times measured as a function of temperature. Copyright © 2007 John Wiley & Sons, Ltd.