Anion Exchange Membranes Based on Styrene–Ethylene/Butene–Styrene Consist of Two Grafting Forms: N Heterocyclic Cations with Alkyl Intervals and Flexible Long Hydrophobic Side Chains

Abstract

In view of the problems of poly(styrene–ethylene/butene–styrene) (SEBS) being difficult to dissolve and poor mechanical properties, a series of SEBS-C16D60-DMHP-X (X represents the cationic graft ratio, 20–40%) anion exchange membranes (AEMs) have been prepared. Graft hydrophobic long chains were applied onto the SEBS skeleton to change its solubility, introducing hydrophobic long chains to help construct microphase separation structures and improve ion conductivity (up to 110.22 mS cm–1). The combination of the rigid ring structure in the ring cation with an alkyl spacer and the toughness of the SEBS skeleton, as well as the free folding of alkyl chains, greatly improved the mechanical properties of the AEM, and the swelling ratio of the membrane is well controlled (25.31%, at 80 °C). The alkaline resistance (conductivity decreased only 10.29% after 1400 h of immersion at 80 °C in 2 M NaOH solution) also continuously increased. The structure of this AEM will provide a very meaningful reference for the development of AEMs.

Study on AEMs with Excellent Comprehensive Performance Prepared by Covalently Cross-Linked p-Triphenyl with SEBS Remotely Grafted Piperidine Cations

“…After the previous research by our research group, 33,34 the ion conductivity and alkaline stability of SEBS-based AEMs have been effectively improved, and the swelling of the membrane has also been inhibited to a certain extent. Due to its unique block structure, SEBS still has inherent drawbacks such as high SR and insufficient mechanical properties, which will limit its commercial application in AEMFCs.…”

Understanding the Effect of Triazole on Crosslinked PPO–SEBS-Based Anion Exchange Membranes for Water Electrolysis

“…A polymer backbone, which alters the characteristics of the membrane, and ion-conducting head groups, which conduct OH − ions, comprise a polymer electrolyte appropriate for use as an AEM [ 20 , 21 ]. Both aryl ether-type and non-aryl ether-type polymers have been employed as polymer backbones, including poly(arylene ether ketone) (PEK) [ 22 , 23 , 24 ], poly(arylene ether sulfone) (PES) [ 25 , 26 ], poly(phenylene oxide) (PPO) [ 27 , 28 , 29 , 30 ], styrene ethylene butylene styrene (SEBS) [ 27 , 31 , 32 , 33 , 34 , 35 ], polyphenylene (PP) [ 12 , 32 , 33 , 36 , 37 ], and polyethylene (PE) [ 38 , 39 , 40 , 41 ]. Ion-conducting groups are often quaternary ammonium [ 12 , 32 , 33 , 34 ], morpholinium [ 42 , 43 ], pyridinium [ 32 , 33 , 44 ], imidazolium [ 45 , 46 ], phosphonium [ 47 , 48 ], and metal coordination compounds [ 49 ].…”