Amination modification of graphene oxide for the in-situ synthesis of sulfonated polyimide-based composite proton exchange membranes.

[Display omitted] • NGO nanoparticles were embedded into SPI polymers through in-situ synthesis. • In-situ synthesis was more favorable for NGO dispersion and well-constructed interface compared to physical blending. • The fracture strength of NGO-SPI composite membrane was approximately 61 MPa. To mitigate the severe degradation of mechanical properties and stability of highly sulfonated proton exchange membranes (PEMs) caused by the sulfonic acid groups, amino-functionalized graphene oxide (AGO) was embedded into sulfonated polyimide (SPI) for the in-situ synthesis of a composite proton exchange membrane. The introduction of AGO nanoparticles facilitated the enhancement of the crystallinity of the composite membrane, with the well-constructed interface and dispersion. The resulting AGO-SPI composite membrane exhibited high mechanical strength and stability. The fracture strength of AGO-SPI composite membrane was approximately 61 MPa, which was 1.85 times higher than that of pure SPI. Meanwhile, the weight loss of AGO-SPI composite membrane in Fenton's reagent was only 2.11 %. Additionally, at 90 °C/98 % RH, the proton conductivity of AGO-SPI composite membrane reached 50.1 mS cm−1, which was 3.53 times higher than that of pristine SPI. The results suggest the promising application prospects of the proton exchange composite membrane. [ABSTRACT FROM AUTHOR]