| Proton exchange membrane fuel cells (PEMFC) are one of the most full-blown technologies which can convert the chemical energy from the reaction of the hydrogen and oxygen into electrical energy. The only byproducts from PEMFC systems are the water and heat. They have been the most promising fuel cells because of their high power density, no noise, low working temperature, etc. Until now, perfluorosulfonic acid membranes have been almost the only PEM used either in practical systems or academics. However, they have disadvantages of high cost, high methanol permeability and reduced proton conductivity at high temperature which limited their abroad applications especially in high temperature fuel cell operation. Therefore, extensive attempts have been performed to the preparation of proton exhange membrane (PEM) by polymers with low cost through sulfonation or adulterating inorganic proton conductors.A series of sulfonated copoly (phthalazinone ether ketone ketone)s (SPPFEKK) were synthesized from 4-(4-hydroxyphenyl)-1(2H)-phthalazinone (DHPZ), 4,4'-hexafiuoroiso-propylidenediphenol (BPAF), 1,4-bi(4-fluorobenzoyl) benzene (DFKK) and 1,4-bi(3-sodium sulfonate-4-fluorobenzoyl) benzene (SDFKK) by direct nucleophilic polycondensation reaction. Their inherent viscosity values are ranged from 1.29 to 1.53 dL/g. The flexible SPPFEKK membranes are prepared by solution casting method from N-methyl-2- pyrrolidone (NMP). The chemical structures of the SPPFEKK are characterized by 1H-NMR and FT-IR, and the properties of the membranes are investigated too. The results indicated that the decomposed temperatures of sulfonic group and the main chain in the SPPFEKK membranes are above 340℃and 550℃, respectively. The tensile strength of the membranes in dry state varies from 57.1 to 69.2 MPa. The proton conductivity and the methanol permeability are increasing with the sulfonation degree (DS) of the membranes. The proton conductivity of the SPPFEKK with sulfonation degree (DS) of 1.2 is 1.0×10-1 S/cm at 95℃. The methanol permeabilities of the SPPFEKK membranes rise from 1.58×10-7 cm2/s to 2.76×10-7 cm2/s with the increment of DS, which is considerably lower than that of Nafion(?) 117.Organic-inorganic hybrids of SPPFEKK or SPPEKK, heteropoly acids (PWA) and silica were prepared by in situ growth of the inorganic network by hydrolysis and condensation of tetraethoxy silane (TEOS) and 3-aminopropyltrimethoxysilane (AS). The AS has the interaction with the PWA and TEOS, which could fix the PWA in the net structure of the SiO2. The influence of the introduction of the PWA/AS/SiO2 in the composite membranes is investigated. The data proves that the introduction of the PWA/AS/SiO2 can restrain the leak of the PWA. The proton conductivities of the SPPFEKK-15 and SPPEKK-15 are 1.0×10-1 S/cm and 8.9×10-2 S/cm at 95℃, which multiply one-fold comparing with pure membranes. The 5% weitht loss temperatures of the composite membranes are 308℃and 304℃. The tensile strength values of them are 76.7 MPa and 70.8 MPa. The stability of the PWA in the composite membranes is characterized by immersing the membranes in water for 7 days and tests the PWA concentration of the water everyday. The result shows that the leakness of the PWA mainly happens in the first three days, and the leak percentage is lower than 0.7%/day. Then the speed of the leakness becomes lower, and the leak percentage is less than 0.3%/day. At the 7th days, PWA in composite membranes gets to stable and the composite membranes still have considerable high proton conductivity (above 6.1×10-2 S/cm).A novel sulfonated diamine, 1,2-dihydro-2-(2-sulfonic-4-amino-phenyl)- 4-[4-(2-sulfonic-4-aminophenoxy)-phenyl]-phthalazin-1-one (S-DHPZDA), is successfully synthesized from 1,2-dihydro-2-(4-amino-phenyI)-4-[4-(4-aminophenoxy)-phenyl]-phthalazin-1-one(DHPZDA) by direct sulfonation. Six series of sulfonated polyimides (SPI-1-6) are prepared by sulfonated diamines, S-DHPZDA, 4,4'-bis(4-aminophenoxy)biphenyl-3,3'-disulfonic acid (BAPBDS), 4,4'-diaminodiphenyl ether-2,2'-disulfonic acid (ODADS), nonsulonated diamines, 4,4'-diaminodiphenyl ether (ODA), 4,4'-bis(4-aminophenoxy) biphenyl (BAPB), DHPZDA and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) by "one-step" copolymerization. The results demostrate that compared to other SPI, SPI-1-6 have improved solubility because of the introduction of the noncoplanar and twist structure phthalazinone moieties in the polymers main chain. The SPI-1-6 could soluble in aprotic organic solvents like m-cresol, NMP, DMSO. The decomposed temperatures of sulfonic group and the main chain in the SPI-1-6 membranes are above 310℃and 560℃, respectively. When the DS is higher than 0.6, the proton conductivity of the SPI reached to 10-2 S/cm at 95℃. The hydrolytic stability of the SPI membranes can be enhanced by inducting flexible bones and more basic sulfonated diamine to the SPI's main chain. SPI-6-80 with high DS (0.8) has the hydrolysis stability of 1280 h, while the SPI-6-20 can maintain its mechanical strength in the water for more than 6000 h at 80℃. The tensile strength of the SPI-1-6 membranes varies from 50.1 to 98.1 MPa. The methanol permeabilities of the SPPFEKK membranes rise from 10-8～10-7 cm2/s with the increment of DS.
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