Preparation of self-crosslinking anion exchange membrane with acid block performance from side-chain type polysulfone

In this work, a novel strategy is designed with the goal of further improving comprehensive performance of anion exchange membrane (AEM). That is, some double-functional monomers with both anion exchange groups and unsaturated double bond pendants, such as N, N-Dimethylallylamine (DMAA), N-Allylmethylamine (AMA), are introduced into Polysulfone backbone in terms of side chains firstly, and then heat-initiated crosslinking occurs during the membrane formation along with the evaporation of solvent and aggregation of polymer chains. For comparison, the conventional AEM is also prepared by heterogeneous amination. Series of characterizations, including chemical composition analyses and micro-structure observations, confirm that desired AEMs are fabricated successfully with a simultaneous occurrence of micro-phase segregation and self-crosslinking. Furthermore, the water uptake, membrane resistance, membrane homogeneity, membrane permselectivity, and thermal, mechanical and chemical stability are investigated to understand the effects of the formed membrane structure. Especially, as-prepared AEMs display outstanding acid block performances. For example, strong base DMAA-4 increase the current efficiency of ED-based acid enrichment to 98.63%, far ahead of that of conventional TMA-4. This work not only indicates acid block performance can be imparted to the strong base AEM but also make it possible to perform the ED-based reclamation of waste acid economically and efficiently.