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Sulfonated polyimide (SPI) based membranes for proton exchange membrane fuel cells (PEMFC) have been synthesized by using a one-step high temperature polymerization method. The membranes were characterized with Fourier transform infrared spectra (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC); water uptake, ion-exchange capacity, proton conductivity and mechanical stability were tested. The results showed that the membranes had good thermal and mechanical stability and exhibited good performance when they were assembled into membrane electrode assemblies (MEAs). Fuel cell testing was performed. The SPI copolymer based MEA was tested under different hydrogen flow rates to compare with the commercially available Nafion® based MEA.

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A series of new poly(ether imide)s containing the naphthalimide moiety were prepared from bis(4‐fluorobenzoyl)naphthalimides and several bisphenols by aromatic nucleophilic displacement polymerization. These polyimides had inherent viscosities in the range of 0.31–1.04 dL/g in chloroform and glass transition temperatures of 283.0–341.6°C by differential scanning calorimetry. The onset temperature for 5% weight loss for all the polymers was over 448°C, as assessed by thermogravimetry at a heating rate 10°C/min in nitrogen. In addition, these novel polyimides exhibited good solubility in organic solvents including N‐methyl‐2‐pyrrolidone, N,N‐dimethylformamide, N,N‐dimethylacetamide, 1,1,2,2‐tetrachloroethane and chloroform. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3227–3231, 1999

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