Constructing lamellar low temperature anion exchange membranes based on polymerized ionic liquid and graphene oxide nanosheets

Polymerized ionic liquid (PIL) of poly(1-vinyl-3-methylimidazolium) chloride (poly(vmim)Cl) and graphene oxide (GO) nanosheets were respectively deposited on the surface of Kevlar aramid nanofibers (KANFs) substrates to construct anion exchange membranes (AEMs). The multilayered microstructure resulted in orderly distributed components, which thus improved the mechanical properties and dimension stability of the lamellar low-temperature AEMs. The imidazolium cations in PIL and the polar oxygen functional groups in GO nanosheets constituted the interconnected hydroxide ion conduction channels in the prepared Kevlar/(PIL/GO)60 membrane. Relative to the ionic liquid (IL) monomer of 1vinyl-3-methylimidazolium chloride, the PIL with polymerized molecular chains could be embedded in GO nanosheets with the formation of a stable microstructure. The Kevlar/(PIL/GO)60 membrane exhibited the enhanced alkaline stability relative to the Kevlar/(IL/GO)60 membrane. Furthermore, the hydroxide conduction behavior in the AEMs at subzero temperatures has been researched in consideration of the long-term exposure in colder conditions of the vehicles equipped with fuel cells. As a result, the Kevlar/(PIL/GO)60 membrane exhibited a hydroxide conductivity of 0.94 mS/cm at -25 & DEG;C, 5.25 mS/ cm at 30 & DEG;C, and 64.7 mS/cm at 80 & DEG;C. Meanwhile, good alkaline stability was revealed from the ten-cycle hydroxide conductivities and long-time hydroxide conductivities. In addition, the PIL enhanced the mechanical strength of the Kevlar/(PIL/GO)60 membrane, with the tensile stress at break increasing by 31.3% compared with that of the Kevlar/(IL/GO)60 membrane.

Automated summary

Polymerized ionic liquid (PIL) and graphene oxide (GO) nanosheets were deposited on the surface of Kevlar aramid nanofibers (KANFs) substrates to construct anion exchange membranes (AEMs). The multilayered microstructure improved the mechanical properties and dimension stability of the AEMs. The interconnected hydroxide ion conduction channels were formed by the imidazolium cations in PIL and the polar oxygen functional groups in GO nanosheets.