Sulfonated poly(phenylsulfone)/fluorinated polybenzoxazole nanofiber composite membranes for proton exchange membrane fuel cells

• SPPSU/multilayered electrospun 6F-PBO composite membranes were prepared.
• Dimensional stability and mechanical property were enhanced simultaneously.
• Methanol resistance performance was improved.

Fluorinated polybenzoxazole (6F-PBO) nanofiber membranes were prepared by electrospinning from poly (hydroxyamide) (PHA) precursor and used to fabricate sulfonated poly(phenylsulfone) (SPPSU)/6F-PBO composite membranes. The electrospun 6F-PBO membrane possessed multilayered structure with nanoscale interstitial voids in and between layers. When compounded with SPPSU, a concrete composite membrane could be obtained. The SPPSU/6F-PBO composite membranes showed enhanced dimensional stability and mechanical property. At 40 °C and 80 °C, the swelling ratio of SPPSU/6F-PBO-H3PO4 is 10.1% and 16.6%, which is reduced by 28% and 25% compared to SPPSU, respectively. The tensile strength and modulus of SPPSU/6F-PBO-H3PO4 is 84.61 MPa and 4.17 GPa, which is 1.17 and 3.60 times of that of SPPSU, 1.97 and 16.68 times of Nafion, respectively. The composite membranes had high water uptake and excellent single cell performance. In the DMFC study, the SPPSU/6F-PBO-H3PO4 composite membranes showed the output circuit potential of 790 mV, compared to that of Nafion (704 mV) and SPPSU (688 mV), indicating improved methanol resistance performance.