129Xe NMR Investigation of the Free Volume in Dendritic and Cross-Linked Polymers
129Xe NMR Investigation of the Free Volume in Dendritic and Cross-Linked Polymers
复制标题
树枝状和交联聚合物中自由体积的 129Xe NMR 研究
DOI：
10.1021/ma9813643
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发表时间：
1999
期刊：
影响因子：
5.5
通讯作者：
A. Andrady
中科院分区：
文献类型：
--
作者：
D. Morgan;E. Stejskal;A. Andrady
使用129 NMR光谱来研究与线性聚合物的交联和树枝状树分子中的广泛链支化相关的自由体积变化。定性研究了聚（氧丙烯）和星形树状聚（酰胺基胺）的模型网络中的自由体积的变化作为交联密度和代的函数，分别。与目前对这些末端连接的网络的理解一致，发现氙的化学位移的变化与末端连接的网络的交联之间的平均分子量的倒数很好地相关。对于树枝状聚合物，氙的化学位移随代数线性变化。适用于树枝状分子的链端自由体积理论的修改形式被用来解释数据。
129Xe NMR spectroscopy was used to study the free-volume changes associated with cross-linking of linear polymers and extensive chain branching in dendritic tree molecules. Qualitative changes in the free volume in model networks of poly(oxypropylene) and in starburst dendrimers of poly(amidoamine) were studied as a function of the cross-link density and the generation, respectively. Consistent with the present understanding of these end-linked networks, the change in chemical shift of the xenon was found to correlate well with the reciprocal of the average molecular weight between cross-links of the end-linked networks. With dendrimers, the chemical shift of xenon varied linearly with the generation number. A modified form of the chain-end free volume theory applicable to dendritic molecules was used to interpret the data.