Amination modification of halloysite nanotubes for the in-situ synthesis of polybenzimidazole-based composite proton exchange membranes

To mitigate phosphoric acid (PA) leaching and the "plasticization effect" in phosphoric acid-doped polybenzimidazole (PA-PBI) membranes, this work employed amino-functionalized nanotubes (AHNTs-NH2) to modify poly(2,5-benzimidazole) (ABPBI) for the in-situ synthesis of composite proton exchange membranes. The introduction of nanoparticles enhanced the strength of the composite membranes, while the surface-rich -NH2 groups captured PA. Additionally, the nanotubular structure provided extra proton pathways. Specifically, the fracture strength of the 2 % AHNTs-NH2/ABPBI composite membrane reached 128 MPa, which was 1.56 times that of ABPBI, and the proton conductivity also significantly improved.