Gasper L, Demco D E, Blümich B
Institut für Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Aachen, Germany.
Solid State Nucl Magn Reson. 1999 Jul;14(2):105-16. doi: 10.1016/s0926-2040(99)00012-0.
Proton nuclear magnetic resonance (NMR) magnetization exchange is used to investigate residual dipolar couplings in a series of cross-linked poly(styrene-cobutadiene) elastomers. A new model for the dipolar unit is used for the evaluation of the signal decay in magnetization exchange experiments. It takes into account an extended residual dipolar coupling network along the polymer chain. It is shown that in the regime of short mixing times, information about the residual dipolar coupling between methine and methylene protons can be obtained which is not affected by other inter- and intramolecular dipolar couplings. The dynamic order parameter of methine-methylene protons is measured and correlated with cross-link density. This study certifies the quality of a filter for magnetization from residual dipolar couplings which exploit magnetization exchange. The filter can be used to generate contrast in NMR images of heterogeneous elastomers. The first proton NMR parameter image of a dynamic order parameter is presented for a phantom made from poly(styrene-cobutadiene) samples with different cross-link densities.
质子核磁共振（NMR）磁化交换用于研究一系列交联聚（苯乙烯 - 共丁二烯）弹性体中的残余偶极耦合。在磁化交换实验中，使用一种新的偶极单元模型来评估信号衰减。该模型考虑了沿着聚合物链的扩展残余偶极耦合网络。结果表明，在短混合时间范围内，可以获得关于次甲基和亚甲基质子之间残余偶极耦合的信息，且不受其他分子间和分子内偶极耦合的影响。测量了次甲基 - 亚甲基质子的动态序参数，并将其与交联密度相关联。本研究验证了利用磁化交换从残余偶极耦合中获取磁化的滤波器的质量。该滤波器可用于在非均质弹性体的NMR图像中产生对比度。针对由不同交联密度的聚（苯乙烯 - 共丁二烯）样品制成的模型，展示了动态序参数的首张质子NMR参数图像。
