Electrostatic Manipulation of Phase Behavior in Immiscible Charged Polymer Blends
Electrostatic Manipulation of Phase Behavior in Immiscible Charged Polymer Blends
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DOI：
10.1021/acs.macromol.1c00095
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发表时间：
2021-03-08
期刊：
影响因子：
5.5
通讯作者：
Fredrickson, Glenn H.
中科院分区：
文献类型：
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作者：
Grzetic, Douglas J.;Delaney, Kris T.;Fredrickson, Glenn H.
微相分离在二元共混的极性聚合物原则上可以被静电稳定，而不需要连接的嵌段聚合物结构。这为通过聚合物电荷密度、盐浓度和介电常数等参数控制微观结构提供了一条途径。在这里，我们使用平衡自一致场理论来研究这种二元共混物的相行为，有或没有反离子和添加盐，并表明它表现出典型的二嵌段共聚物熔体的有序相。我们演示了两种聚合物的电荷密度和介电常数的差异如何影响该系统的相行为。特别是，我们发现球相的相窗受到显著影响，当少数组分具有比周围基体更高的介电常数时，可以稳定Frank-Kasper相sigma和A15。由于该系统中的畴长尺度是静电确定的，并且不受块结构施加的链拉伸限制，因此我们的研究结果提出了一条通往大单元复杂球体相的可能途径。这些预测将最容易在带相反电荷的聚合物离子液体中得到验证，在这种情况下，体积大且去局部化的电荷将有助于在无溶剂环境中实现平衡。
Microphase separation in a binary blend of oppositely charged polymers can in principle be stabilized electrostatically without the need for connected block polymer architectures. This provides a route to control microstructure via parameters such as polymer charge density, salt concentration, and dielectric constant. Here, we use an equilibrium self-consistent field theory to study the phase behavior of such a binary blend, with or without counterions and added salt, and show that it exhibits the canonical ordered phases of a diblock copolymer melt. We demonstrate how differences in the charge density and the dielectric constant of the two polymers affect phase behavior in this system. In particular, we find that the phase windows for sphere phases are dramatically affected and that the Frank-Kasper phases sigma and A15 can be stabilized when the minority component has a higher dielectric constant than the surrounding matrix. Since the domain length scale in this system is determined electrostatically and is not subject to chain-stretching limitations imposed by block architectures, our results suggest a possible route to large-unit-cell complex-sphere phases. These predictions will be most easily tested in oppositely charged polymeric ionic liquids, where the bulky and de-localized charges should aid equilibration in a solvent-free environment.