The structure of ionomers is often trapped in far-from-equilibrium states as a result of clustering of the ionizable groups. Solvent tweaking of the ionic clusters to allow rearrangements to form thermodynamic stable systems at ambient temperature is a promising path for constraint release, offering a path to form equilibrium structures. However, it requires a common solvent for the highly segregated ionic clusters and the polymer matrix. The current study probes the structure and dynamics of sulfonated polystyrene ionomer melts swollen with tetrahydrofuran (THF), a hydrophobic yet polar solvent, by using fully atomistic molecular dynamics simulations. The structure and dynamics of these swollen melts were calculated and correlated with the characteristics of the ionic clusters. We find that THF partitions to the polystyrene-rich domains as well as to the interface of the ionic domains, resulting in enhanced dynamics of the chains on all length scales measured, as expected for a swollen melt. Surprisingly though, the cluster size increases with time in the presence of THF, indicating that the solvent releases some of the constraints, enabling the growth of ionic assemblies.

中文翻译：

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THF 溶胀聚苯乙烯离聚物熔体的结构和动力学


由于可电离基团的聚集，离聚物的结构常常陷入远离平衡的状态。对离子簇进行溶剂调整，以允许在环境温度下重排形成热力学稳定系统，是释放约束的一条有希望的途径，为形成平衡结构提供了一条途径。然而，它需要一种用于高度分离的离子簇和聚合物基质的通用溶剂。目前的研究通过使用完全原子分子动力学模拟，探讨了用四氢呋喃（THF）（一种疏水性极性溶剂）溶胀的磺化聚苯乙烯离聚物熔体的结构和动力学。计算了这些膨胀熔体的结构和动力学，并将其与离子簇的特征相关联。我们发现，THF 分配到富含聚苯乙烯的域以及离子域的界面，从而导致在测量的所有长度尺度上链的动力学增强，正如对溶胀熔体的预期一样。但令人惊讶的是，在 THF 存在的情况下，簇尺寸随着时间的推移而增加，这表明溶剂释放了一些限制，从而促进了离子组装体的生长。