| Poly(phthalazinone ether ketone) (PPEK) is a new kind of high performance polymer and has excellent mechanical properties, thermal stability, chemical and oxidative resistance. The aim of this work is to modify PPEK by means of sulfonation, chloromethylation/quaternization, doping sulfonated PPEK with inorganic particles such as cesium hydrogen sulfate (CS), zirconium hydrogen phosphate hydrate (ZrP) and 12-phosphotungstic acid (PWA), to prepare polymer electrolyte membranes (PEM) for fuel cells, and to study the relationship between structure and properties of the polymer electrolyte membranes.Firstly, the sulfonated PPEKs (SPPEKs) were synthesized by reacting PPEK with 98% concentrated sulfuric acid or 98% concentrated sulfuric acid and chlorosulfonic acid mixture under 80～100℃. The presence of sulfonic acid groups in SPPEKs was confirmed by Fourier transform infrared analysis, Energy Dispersive X-Ray and 1H NMR spectrum. The optimum reaction conditions was 5g PPEK in the mixture of 70ml concentrated sulfuric acid of 98% and 10ml chlorosulfonic acid at 90℃ for 3h. The methanol permeability of SPPEK membrane was 1.07×10-7 cm2/s, which was about 20 times lower than that of Nafion 117 (2.38×10-6 cm2 s(-1)) under similar condition. The SPPEK membrane showed the highest proton conductivity of 3.12×10-2 S/cm at 95℃, which was in the range needed for the high performance fuel cell PEM.Secondly, the incorporation of the PWA into the SPPEK membrane did not damage the thermal stability and mechanical properties of the PWA/SPPEK hybrid membranes badly. The methanol permeability of the hybrid membrane containing 10 wt% PWA (MP10) was 1.02×10-7 cm2/s, which was about 20 times lower than that of Nafion 117 under similar condition. MP10 showed the highest proton conductivity of 0.17 S/cm at 80℃, which was higher than that of Nafion 117 (0.11 S/cm). The methanol permeabilities of a-ZrP/SPPEK hybrid membrane prepared from swell-dipping method (Mz5) and direct blending method (Mz10) were 1.52×10-7 and 1.74×10-7 cm2 s-1 respectively. The highest proton conductivities of Mz5 and Mz10 were 7.65 ×10-2 S/cm and 3.26×10-2 S/cm at 95℃. Doping CS into SPPEK membrane had a negative impact on the properties of CS/SPPEK hybrid membranes. The methanol permeability and thehighest proton conductivity of the hybrid membrane containing 10% CS were 1.40× 10-7 cm2/s and 2.25×10-2 S/cm respectively, which were lower than that of membrane SPPEK.Lastly, the quaternized PPEKs (QPPEKs) were modified by chloromethylation/ quaternization, and the alkaline QPPEK membrane had a methanol permeability 7.21× 10-7 cm2/s and the highest anion conductivity 1.14×10-2S/cm. It might be suitable for low temperature alkaline polymer electrolyte membrane fuel cells.
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