“Pseudo solid” nuclear spin echo study of poly(ethylene oxide) grafted on silica. Comparison with magic‐angle spinning technique results
“Pseudo solid” nuclear spin echo study of poly(ethylene oxide) grafted on silica. Comparison with magic‐angle spinning technique results
复制标题
二氧化硅接枝聚环氧乙烷的“伪固体”核自旋回波研究与魔角旋转技术结果的比较。
DOI：
10.1002/cmr.a.21365
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
H. Hommel
中科院分区：
文献类型：
--
作者：
T. Tajouri;Mohamed Aymen Ben Mariem;H. Hommel
用~ 1H NMR研究了聚氧化乙烯（PEO）接枝到二氧化硅上的聚合物/固体界面。对于接枝聚合物，偶极相互作用是自旋-自旋弛豫过程中的一个重要因素。为此，使用偶极相互作用的未被运动平均为零的部分。“伪固体”自旋回波确实可以给出非零平均偶极相互作用的估计。适当的脉冲序列允许对横向磁化弛豫中涉及的平均偶极自旋耦合进行标准测量。一些主要的参数，如分子量的链，接枝率，和温度的松弛，并最终对浓度的影响，其次是“伪固体”的自旋回波。魔角旋转技术也被使用。样品旋转证实了由中心线的变窄和边带的出现，残余偶极相互作用的存在，其揭示了在表面处的高单体单元的浓度。边带的研究允许计算作为温度的函数的二阶矩。一个公平的协议是通过这两个独立的技术：伪固体回声和魔角旋转。
The polymer/solid interface of Poly (ethylene oxide) (PEO) grafted on silica is studied by1H NMR. For grafted polymers, the dipolar interaction is an important factor in the spin–spin relaxation process. For this purpose, the part of the dipolar interaction that is not averaged to zero by the motion is used. The “pseudo solid” spin echo can indeed give an estimation of the nonzero average dipolar interactions. The appropriate pulse sequence permits a standard measurement of the average dipolar spin coupling involved in the transverse magnetization relaxation. The influence of some major parameters such as molecular weights of the chains, grafting ratios, and temperatures on the relaxation and ultimately on the concentration is followed by “pseudo solid” spin echo. The magic‐angle spinning technique is also used. The sample rotation confirms by the narrowing of the central line and the appearance of side bands, the existence of a residual dipolar interaction which reveals the concentration of high monomer units at the surface. The study of the side bands permits to calculate the second moment as a function of temperature. A fair agreement is obtained by these two independent techniques: pseudo solid echo and magic‐angle spinning.