Ionic Aggregate Structure in Ionomer Melts: Effect of Molecular Architecture on Aggregates and the Ionomer Peak
Ionic Aggregate Structure in Ionomer Melts: Effect of Molecular Architecture on Aggregates and the Ionomer Peak
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DOI：
10.1021/ja209142b
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发表时间：
2012-01-11
影响因子：
15
通讯作者：
Frischknecht, Amalie L.
中科院分区：
文献类型：
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作者：
Hall, Lisa M.;Seitz, Michelle E.;Frischknecht, Amalie L.
我们进行了一套全面的粗粒度的分子动力学模拟的离聚物熔体与不同的聚合物结构，并比较结果的实验，以了解在分子水平上的离子聚集。模型离聚物含有周期性或随机间隔的带电珠粒，放置在聚合物主链内或悬挂在聚合物主链上，并明确处理抗衡离子。离子聚集体结构被确定为带电珠粒的间距的函数，并且还取决于带电珠粒是否在聚合物主链中或悬挂于主链。低波矢离聚物峰的逆散射中观察到的所有系统，它是最尖锐的离聚物与周期性间隔悬挂带电珠与带电珠之间的大间距。更改为随机或更短的间距会将峰移动到较低的波矢量。我们提出了新的实验X-射线散射数据Na+-中和的聚（乙烯-共-丙烯酸）离聚物，显示相同的两个趋势，在离聚物峰，类似结构的离聚物。内和聚集体之间的顺序，以及这与用于拟合离聚物峰的各种模型的关系，进行了量化和讨论。
We perform a comprehensive set of coarse-grained molecular dynamics simulations of ionomer melts with varying polymer architectures and compare the results to experiments in order to understand ionic aggregation on a molecular level. The model ionomers contain periodically or randomly spaced charged beads, placed either within or pendant to the polymer backbone, with the counterions treated explicitly. The ionic aggregate structure was determined as a function of the spacing of charged beads and also depends on whether the charged beads are in the polymer backbone or pendant to the backbone. The low wavevector ionomer peak in the counterion scattering is observed for all systems, and it is sharpest for ionomers with periodically spaced pendant charged beads with a large spacing between charged beads. Changing to a random or a shorter spacing moves the peak to lower wavevector. We present new experimental X-ray scattering data on Na+-neutralized poly(ethylene-co-acrylic acid) ionomers that show the same two trends in the ionomer peak, for similarly structured ionomers. The order within and between aggregates, and how this relates to various models used to fit the ionomer peak, is quantified and discussed.