Crosslinked anion exchange membranes with connected cations

Wenxu Zhang, Ye Liu, Xiaohui Liu, James L. Horan, Ying Jin, Xiaoming Ren, S. Piril Ertem, Soenke Seifert, Matthew W. Liberatore, Andrew M. Herring, Edward Bryan Coughlin

Index: 10.1002/pola.28935

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Abstract

ABSTRACT The selective transport of ions has crucial importance in biological systems as well as modern-day energy devices, such as batteries and fuel cells, and water purification membranes. Control over ion movement can be exerted by ligation, ion channel dimensions, solvation, and electrostatic interactions. Polyelectrolyte hydrogels can provide aligned pathways for counter ion transport but lack mechanical integrity, while polyelectrolyte membranes typically suffer from the absence of an ion transport channel network. To develop polymer membranes for improved ion transport, we present the design of a novel material that combines the advantages of aligned pathways found in polyelectrolyte hydrogel and mechanical robustness in conventional membranes. The ionic species were organized via controlled copolymerization of a quaternizable monomer. Additionally, dimensional stability was then incorporated through a cast/crosslinking method to lock in the network of connected cationic groups. This strategy resulted in dramatically enhanced ion transport, as characterized by ionic conductivities (>80 mS/cm for Cl–, and ∼200 mS/cm for OH–). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 00, 000–000 Ion transport materials find various applications, such as water purification and fuel cells. Introducing crosslinking can improve the mechanical integrity and control water sorption of the cells; however, this sacrifices conductivity. Here, a novel material is developed with a one-step cast/crosslinking method to incorporate the feature of chemically linked cations. This strategy significantly enhances the ionic conductivities.