Synthesis and characterization of piperazine containing polyaspartimides blended polysulfone membranes for fuel cell applications

A new polyaspartimide was synthesized via a Michael addition reaction of an aromatic bismaleimide (BMI) with aminoethylpiperazine (AEP) at 1:1 molar ratio. IR and NMR spectral techniques were used for the characterization of the newly synthesized polyaspartimide (PAI). The copolymer, piperazine containing polyaspartimide, was then blended with polysulfone (Psf) at 3 and 6 wt % by dissolving in the solvent DMF. The blend membranes are studied for their water uptake, ion exchange capacity, swelling ratio, chemical stability, morphology, and proton conductivity. It is observed from morphological studies that the porous structure of polysulfone has been retained even after the incorporation of PAI. The percentage water uptake of membranes of different compositions reveals that the blending of copolymer PAI with polysulfone enhances the water uptake nature of the membrane. The chemical stability on membranes revealed that Psf/PAI-6% has a degradation of about 2.26% which is much lower than that of neat Psf membranes (3.43%), higher chemical stability. The neat Psf found to have an IEC value of 8.045 mmol/g and the IEC values increase with the addition of PAI. The highest value of IEC is obtained for the 6% PAI loaded Psf blend membrane with a value of 8.235 mmol/g. The study on the capacity of proton exchange has proved that the copolymer blend membrane is given higher proton conductivity to the extent of 4.09 × 10-4 S cm-1.