Preparation of Branch Polyethyleneimine (BPEI) Crosslinked Anion Exchange Membrane Based on Poly(styrene‐ b ‐(ethylene‐ co ‐butylene)‐ b ‐styrene) (SEBS)

Anion exchange membranes with chemical stability, high conductivity, and high mechanical properties play an important role in alkaline fuel cells. Here, a series of CPX anion exchange membranes based on poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) and branch polyethyleneimine (BPEI) are achieved by casting, in which BPEI acts as both a crosslinking agent and an OH− conducting functional group. The introduction of BPEI facilitates the formation of good hydrophilic/hydrophobic microphase separation structure, thus improving the ion transport channel of CPX membrane. The physicochemical and electrochemical properties of the CPX membrane are significantly improved when the mass ratio of SEBS to BPEI is within an appropriate range. The OH− conductivity of the CP2 membrane (the mass ratio of SEBS to BPEI is 2) can reach 66.63 mS cm−1 at 80 °C, and more than 80% initial OH− conductivity is maintained in 1.0 m NaOH solution for 20 d at 60 °C. The strategy of using a polymer with excellent alkali resistance and oxidation resistance as the main body and introducing a conductive group that can construct microphase separation can simultaneously improve the conductivity and membrane stability. This viable strategy is a promising construction method for anion exchange membranes that can be applied to fuel cells.