Abstract:A conventional method for preparing a polyvinylidene fluoride (PVDF) homogeneous cation exchange membrane is improved. The PVDF homogeneous cation exchange membrane was directly prepared by using initiators and sulfonation with concentrated sulfuric acid. A series of PVDF cation exchange membranes using the initiator benzoyl peroxide (BPO) and/or 2,2'-azobis(2-methylpropionitrile) (AIBN) were prepared by solvent evaporation. The effects of different initiators and their contents on the membrane structure and membrane properties were investigated. The physical morphology and chemical structure of PVDF cation exchange membranes were analyzed by thermal field emission scanning electron microscopy (FE-SEM) and Fourier Transform infrared spectroscopy (FTIR). The results show that PVDF and styrene form a semi-interpenetrating network structure in the cation exchange membrane containing BPO. In the cation exchange membrane containing AIBN, styrene is grafted on the linear PVDF chain and forms a phase separation structure. The structure and properties of the PVDF cation exchange membrane are affected by the content of AIBN and BPO. When the AIBN content is 0.25 g and the BPO content is 0.1 g, the membrane resistance of the ion exchange membrane reaches a minimum of 4.2 Ω∙cm^2. The ion exchange capacity is up to 1.6 meq/g; when the AIBN content is 0.15 g and the BPO content is 0.1 g, the migration number of the ion exchange membrane is 95.15%. The effects of different initiators and their contents on membrane resistance and migration number were further verified by cyclic voltammetry and chronopotentiometry.