One-pot solvent-free synthesis of cross-linked anion exchange membranes for electrodialysis

• AEM has been synthesized by a one-pot solvent-free strategy.
• Crosslinking and functionalization have been conducted simultaneously.
• The optimized membrane exhibits excellent performances in electrodialysis.

Solvent-free strategy has attracted a broad interest in preparation of ion exchange membranes in recent years stemming from the no need of organic solvents and facilitated construction of highly crosslinking networks. However, post-functionalization is commonly required for further introducing ion-exchange groups. In this study, we report a one-pot solvent-free synthesis of cross-linked anion exchange membranes (AEMs) without the need for post-functionalization. We firstly dissolved brominated poly (2, 6-dimethyl-1, 4-phenylene oxide) (BPPO) in liquid monomers mixture of 4-vinylbenzyl chloride (VBC) and styrene without any organic solvent, then added appropriate amount of N-vinylimidazole and N-methylimidazole to introduce imidazolium groups into both of polyelectrolyte and solvents. The transparent, robust and crosslinked AEMs were obtained by the thermal crosslinking of the unsaturated moieties during the membrane forming process. This approach, distinct from the classical post-functionalization processes, performs crosslinking and functionalization simultaneously. Particularly, imidazolium cations locating on cross-links endow the resultant membrane a high concentration of charge carriers (ion-exchange capacity) for target low resistance, while maintain a high mechanical stability.

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