Synthesis and Properties of Highly Branched Comb-shaped Poly (aryl ether sulfone) s/imidazolium-functionalized Graphene Oxide Anion Exchange Composite Membranes

1-( 6-Bromohexyl)-3-methylimidazolium bromide-functionalized graphene oxide (6BrIm-GO) was synthesized with hydroxylated graphene oxide (GO-OH) and 1-(6-bromohexyl)-3-methylimidazolium bromide (6BrIm) by the Williamson reaction. After introducing 6BrIm-GO into the matrix of highly branched comb-shaped poly (aryl ether sulfone) s (ImHBPES-8) , a set of anion exchange nano-composite membranes (ImHBPES-8/x-6BrIm-GO) were prepared via physical blending, solution casting and ion exchange. 6BrIm-GO, which acted as a kind of unique functional nano-filler within membranes, provided more sites for hydroxide ion transport. It was the introduction of 6BrIm-GO to ImHBPES-8 that enhanced not only mechanical strength but also hydroxide conductivity for the ImHBPES-8 membrane. The structure-property relationships of the as-prepared membranes were investigated in detail by regulating the content of 6BrIm-GO. This results revealed that all of the ImHBPES-8/x-6BrIm-GO composite membranes showed better overall properties than the ImHBPES-8 membrane after introducing 6BrIm-GO into ImHBPES-8. Among of these membranes , the ImHBPES/0. 75%-6BrIm-GO composite membrane exhibited the most outstanding features. Tensile strength of the membrane was 18. 32 MPa , which was 22. 9% higher than the ImHBPES-8 membrane. Hydroxide conductivity of the ImHBPES/0. 75%-6BrIm-GO composite membrane in this work reached a maximum value of 79. 8 mS/cm at 80 degrees C. Moreover, this membrane remained approximately 70% of its initial hydroxide conductivity , which was far over the ImHBPES-8 membranes (56%), after immersing the membrane into a 1 mol/L aqueous KOH solution at 60 degrees C for 300 h, indicating that the ImHBPES/0. 75%-6BrIm-GO composite membrane possessed an excellent alkaline resistance stability. In summary, these results suggested that the ImHBPES/0. 75%-6BrIm-GO composite membrane with remarkable overall performance had a great potential in alkaline polyelectrolyte fuel cells.