Aromatic polyamides are well known as one of the most important high-performance polymers due to their excellent thermal stability and other outstanding properties．However

the present commercial polyamides are insoluble and do not melt below their decomposition temperature

which restrict their processing and applications．In the paper

1

2-dihydro-2-(4-aminophenyl)-4-[4-(4-aminophenonxyl) phenyl]-phthalazin-1-one

a novel diamine monomer containing the phthalazinone moiety was synthesized

and a series of polymers based on this monomer were synthesized with the Yamazaki method and studied．The novel diamine and different aromatic diacides were used to synthesize polyamides and co-polyamides which were soluble in polar aprotic solvents such as DMAc

NMP and had inherent viscosity of 1.26～1.51 dL/g(25℃

NMP)．The Tg values of the polyamides were all above 300℃．The properties of polyamides and co-polyamides were studied．The aromatic polyamide films were prepared by the thermal conventional method．The films had tensile strength of 62～89 MPa

elongation to break of 5％-9％ and tensile modulus of 2.2～2.9 GPa．The order of the coefficient of electrical resistance was 1014～1016．Their uhtrafiltration membrane also had good separation properties．The rejection against PEG 12000 could be up to 99.7％ when the water flux was 175 kg／m2·h．