As distinguished from the conventional preparation of poly(aryl ether ketone)s by utilizing 4

4'-difluorobenzophenone

a series of poly(4-phthalazinone ether sulfone ketone)s (PPESKs) were prepared from 4-(4-hydroxylphenyl)-2

3-phthalazin-1-one (DHPZ) with 4

4'-dichlorodiphenyl sulfone (DCS) and a less reactive but cheaper monomer

4

4'-dichlorobenzophenone (DCK) by solution polycondensation.The polymerization was conducted at 210℃ in sulfolane by two steps

which successfully resolved the problems resulted from the low reactivity of DCK in the nucleophilic substituent reaction.The inherent viscosities of the obtained polymers were in the range of 0.40~0.61 dL/g.The structures of the resultant polymers were characterized by FTIR and 1H-NMR.The properties of the polymers were also investigated.The polymers exhibited outstanding thermal properties.Their glass transition temperatures were in the range of 264℃ to 299℃

which is consisted with Fox Equation well.And their temperatures for 5% weight loss in nitrogen were above 500℃.The PPESKs can form transparent

strong and flexible films from their N-methyl-2-pyrrolidone NMP solution

and these films showed excellent mechanical properties with tensile strength above 68 MPa

Youngs moduli above 0.80 GPa and elongation at break above 19%.Thus this kind of polymers with low cost exhibits a promising wide market and applications in composites

high temperature adhesives and insulating coatings.