Highly conductive and robust composite anion exchange membranes by incorporating quaternized MIL-101 （Cr）

With well-defined channels and tunable functionality, metal-organic frameworks （MOFs） have inspired the design of a new class of ion-conductive compounds. In contrast to the extensive studies on proton- conductive MOFs and related membranes attractive for fuel cells, rare reports focus on MOFs in preparation of anion exchange membranes. In this study, chloromethylated MIL-101 （Cr） was prepared and incor- porated into chloromethylated poly （ether ether ketone） （PEEK） as a multifunctional filler to prepare imidazolium PEEK/imidazolium MIL-101（Cr） （ImPEEK/ImMIL-101（Cr）） anion exchange membrane after synchronous quaternization. The successful synthesis and chloromethylation of MIL-101（Cr） were veri- fied by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy while the enhanced performance of composite membranes in hydroxide conductivity, mechanical strength and dimensional stability were evaluated by alternating-current impedance, electronic stretching machine and measurement of swelling ratio. Specifically, incorporating 5.0wt% ImMIL-101（Cr） afforded a 71.4% increase in hydroxide conductivity at 20℃, 100% RH. Besides, the composite membranes exhibited enhanced dimensional stability and mechanical strength due to the rigid framework of ImMIL- 101（Cr）. At room temperature and the ImM1L-101（Cr） content of 10wt%, the swelling ratio of the ImPEEK/lmMIL-101（Cr） was 70.04% lower while the tensile strength was 47.5% higher than that of the pure membrane.