Measurement of Spin Diffusion Coefficients in Glassy Polymers: Failure of a Simple Scaling Law
Measurement of Spin Diffusion Coefficients in Glassy Polymers: Failure of a Simple Scaling Law
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玻璃态聚合物中自旋扩散系数的测量：简单缩放定律的失败
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
G. Weill
中科院分区：
文献类型：
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作者：
B. Meurer;G. Weill
对于一系列聚合物，自旋扩散系数D不按比例缩放，如从基于规则间隔的核的简单表达式预测的那样。我们比较了PVA和聚苯乙烯的D，它们的侧基是质子化的或氘代的。对于聚苯乙烯，D从600-800显著降低到65 nm 2 ·s-1。对于PVA，D对于完全质子化的链已经很小，并且仅从170 nm 2·s-1略微减小到130 nm 2·s-1。这表明快速旋转的甲基对相邻链之间的自旋扩散没有明显的贡献，并证实平均质子密度不是控制D的相关参数。
For a series of polymers, the spin diffusion coefficients D do not scale as predicted from a simple expression based on regularly spaced nuclei. We compare D for PVA and polystyrene with their side group either protonated or deuterated. For polystyrene, D is considerably reduced from 600-800 to 65 nm 2 ·s -1 . For PVA, D is already small for the fully protonated chain and is only slightly reduced from 170 to 130 nm 2 .s -1 . This indicates that the rapidly rotating methyl group does not contribute appreciably to spin diffusion between neighboring chains and confirms that the mean proton density is not the pertinent parameter to control D.