Sulfonated poly(phthalazinone ether nitrile ketone)s(SPPENK)with pendent sulfonate groups were synthesized by direct polycondensation from 4-(4-hydroxyphenyl)-1(2H)-phthalazinone(DHPZ)

disodium 3

3'-disulfonate-4．4’-difluorobenzophenpne (SDFB)

4

4’-difluorobenzophenone (DFB)and 2

6-dicholobenzene (DCBN)．The intrinsic viseosity of SPPENK was in the range of 0．58～2．0 dL／g．FT—IR

1H—NMR and wide—X—ray scattering were used to characterize the structures of the eopolymers．The thermo—stability of the eopolymers was detected bv DSC and TGA．Tough films were cast successfully from N—methylpyrrolidone solutions．The ion exchange capacity (IEC) values were 0．91～2．06 meq·g-1．The swelling ratios of resulted membranes were 9％～21％

which is much lower than those of Nafionll35 and other reported sulfonated poly(aryl ether ketone)8 and poly(aryl ether sulfone)s membranes with the same ion exchange eapacity．