Rheological properties of sulfonated polystyrene ionomers at high-ion contents
Rheological properties of sulfonated polystyrene ionomers at high-ion contents
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DOI：
10.1007/s00397-021-01265-5
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发表时间：
2021-03
期刊：
影响因子：
2.3
通讯作者：
Xinyue Yu;Xiao Cao;Quan Chen
中科院分区：
文献类型：
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作者：
Xinyue Yu;Xiao Cao;Quan Chen
用X射线散射、差示扫描量热法(DSC)和线性粘弹性(LVE)研究了以铯为反离子的无缠结随机磺化聚苯乙烯离聚体的结构和动力学。大尺寸的铯离子导致低的缔合能，使得对于高离子含量的样品，即具有高达19%的电离单体的样品，可以考察动力学。X射线散射数据显示有一个离子峰，表明形成了离子聚集体。差示扫描量热法(DSC)揭示了玻璃化转变过程，当离子含量高于10%时，玻璃化转变过程向高温区移动，并明显变宽。根据这种加宽，在LVE中看到的玻璃和橡胶区域合并成一个具有广泛松弛分布的广泛过程。我们认为，当每条链上的离子基团的数量与每条链上的Kuhn链段的数量相当时，这种转变就会发生，从而离子基团之间的聚合物链变得不灵活。
Structure and dynamics are examined for unentangled randomly-sulfonated polystyrene ionomer samples with cesium as counterion, using the X-ray scattering, DSC, and linear viscoelasticity (LVE) measurements. The large size of cesium cation leads to low association energy, enabling the dynamics to be examined for the high-ion-content samples, i.e., samples having a fraction of ionized monomerspup to 19%. X-ray scattering data shows an ionic peak, indicating the formation of ion aggregates. DSC reveals the glass transition process that shifts to higherTand broadens significantly when the ion contentpis higher than 10%. In accordance with this broadening, the glassy and rubbery regimes seen in the LVE merge into one broad process with a wide relaxation distribution. We propose that the transition occurs when the number of ionic groups per chain becomes comparable to that of Kuhn segments per chain so that the polymer strands between ionic groups become non-flexible.