Ion transport properties of mechanically stable symmetric ABCBA pentablock copolymers with quaternary ammonium functionalized midblock

TitleIon transport properties of mechanically stable symmetric ABCBA pentablock copolymers with quaternary ammonium functionalized midblock
Publication TypeJournal Article
Year of Publication2017
AuthorsS. Piril Ertem, Benjamin R. Caire, Tsung-Han Tsai, Di Zeng, Melissa A. Vandiver, Ahmet Kusoglu, Soenke Seifert, Ryan C. Hayward, Adam Z. Weber, Andrew M. Herring, E. Bryan Coughlin, Matthew W. Liberatore
JournalJournal of Polymer Science Part B: Polymer Physics
Volume55
Issue7
Pagination612 - 622
Date Published01/2017
Abstract

Anion exchange membranes (AEMs) are a promising class of materials for applications that require selective ion transport, such as fuel cells, water purification, and electrolysis devices. Studies of structure–morphology–property relationships of ion-exchange membranes revealed that block copolymers exhibit improved ion conductivity and mechanical properties due to their microphase-separated morphologies with well-defined ionic domains. While most studies focused on symmetric diblock or triblock copolymers, here, the first example of a midblock quaternized pentablock AEM is presented. A symmetric ABCBA pentablock copolymer was functionalized to obtain a midblock brominated polymer. Solution cast films were then quaternized to obtain AEMs with resulting ion exchange capacities (IEC) ranging from 0.4 to 0.9 mmol/g. Despite the relatively low IEC, the polymers were highly conductive (up to 60 mS/cm Brat 90 °C and 95%RH) with low water absorption (<25 wt %) and maintained adequate mechanical properties in both dry and hydrated conditions. X-ray scattering and transmission electron microscopy (TEM) revealed formation of cylindrical non-ionic domains in a connected ionic phase. 

DOI10.1002/polb.24310
Short TitleJ. Polym. Sci. Part B: Polym. Phys.
Refereed DesignationRefereed