In this study, new fluorine-siloxane-containing polybenzimidazole (PBI) copolymers were synthesized by copolymerization of 3,3'-diaminobenzidine, 2,2-bis(4-carboxyphenyl)-hexafluoropropane (HFA), and 1,3 bis(carboxypropyl) tetramethyldisiloxane (BTMDS) with different molar ratios. PBI copolymer membranes were prepared by solution-casting and then doped with phosphoric acid. The structures of PBI copolymers were characterized by FTIR and X-ray diffraction. The solubility of the PBI copolymers was significantly increased by the introduction of the bulky HFA group and the flexible BTMDS group into the polymer backbone. The PBI copolymers still maintained good thermal stability and mechanical properties. Because of the introduction of the flexible and hydrophobic siloxane group in the polymer backbone, the methanol permeability was reduced and the proton conductivity under anhydrous condition at high temperatures was increased compared to the PBI without the siloxane group.
All Science Journal Classification (ASJC) codes
- Surfaces, Coatings and Films
- Polymers and Plastics
- Materials Chemistry