Ma Boran, Olvera de la Cruz Monica
Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States.
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
J Phys Chem B. 2021 Apr 1;125(12):3015-3022. doi: 10.1021/acs.jpcb.0c08707. Epub 2021 Feb 26.
Ion-containing polymers have numerous potential applications as energy storage and conversion devices, water purification membranes, and gas separation membranes, to name a few. Given the low dielectric constant of the media, ions and charges on polymers in a molten state interact strongly producing large effects on chain statistics, thermodynamics, and diffusion properties. Here, we discuss recent research accomplishments on the effects of ionic correlation and dielectric heterogeneity on the phase behavior of ion-containing polymers. Progress made in studying ion transport properties in these material systems is also highlighted. Charged block copolymers (BCPs), among all kinds of ion-containing polymers, have a particular advantage owing to their robust mechanical support and ion conducting paths provided by the segregation of the neutral and charged blocks. Coulombic interactions among the charges play a critical role in determining the phase segregation in charged BCPs and the domain size of charge-rich regions. We show that strongly charged BCPs display ordered phases as a result of electrostatic interactions alone. In addition, bulky charge-containing side groups attached to the charged block lead to the formation of morphologies that provide continuous channels and better dissociation for ion conduction purposes. Finally, a few avenues for designing ion-containing polymers for energy applications are discussed.
含离子聚合物有许多潜在应用，比如用作能量存储与转换装置、水净化膜和气体分离膜等等。鉴于介质的低介电常数，处于熔融状态的聚合物上的离子和电荷会强烈相互作用，对链统计、热力学和扩散性质产生重大影响。在此，我们讨论了关于离子相关性和介电不均匀性对含离子聚合物相行为影响的近期研究成果。还重点介绍了在研究这些材料体系中离子传输性质方面所取得的进展。在各类含离子聚合物中，带电嵌段共聚物（BCP）具有独特优势，因为其中性和带电嵌段的分离提供了强大的机械支撑和离子传导路径。电荷之间的库仑相互作用在决定带电BCP中的相分离以及富电荷区域的畴尺寸方面起着关键作用。我们表明，强带电BCP仅由于静电相互作用就会呈现有序相。此外，连接到带电嵌段上的含大体积电荷的侧基会导致形成形态，这些形态能提供连续通道并为离子传导目的实现更好的离解。最后，讨论了一些为能量应用设计含离子聚合物的途径。
