A series of poly(phthalazinone ether nitrile)s containing phenyl-s-triazine ring moiety in the main chain has been synthesized by the nucleophilic displacement polycondensation reaction of 2

4-bi(4-fluorophenyl)-6-phenyl-1

3

5-triazine (BFPT)

a kind of heterocyclic aromatic difluoride monomer containing phenyl-s-triazine ring moiety

and 2

6-difuorobenzonitrile

as coreactants

with bisphenol-like monomer 4-(4-hydroxylphenyl)(2H)-phthalazin-1-one (DHPZ).The structures of the copolymers were detected by FTIR and 1H-NMR spectra.The obtained polymers having inherent viscosities in the range of 0.65~1.02 dL/g have no crystallinity peaks in their X-ray diffraction patterns

indicating that they are amorphous.The polymers exhibit only one Tg

suggesting that PPEP containing phenyl-s-triazine segments and PPEN containing nitrile segments in the copolymer are miscible.Their glass transition temperatures (Tg) are in the range of 301~337℃.They exhibit high thermal stability with no significant weight loss up to 500℃ in nitrogen (in N2:Td 5%510℃)

and the char at 800℃ is more than 60%.The content of phenyl-s-triazine in the polymer backbone is more effective in improving the thermal properties than that of nitrile.The Tg and Td 5% of the copolymers increase with increasing the content of phenyl-s-triazine structure in the main chain.However

the copolymers containing lower than 50% phenyl-s-triazine structure could be soluble in NMP

DMAc and chloroform at room temperature.The copolymers having more than 50% phenyl-s-triazine moiety could resolve in NMP and DMAc at heating.All films of the polymers synthesized possess good mechanical properties in the room temperature.Their tensile strengths are ranging from 72 MPa to 84 MPa with 7.6%~11% of elongation at break

which decreases with incorporating more phenyl-s-triazine moiety in the polymer backbone.