A novel series of soluble and curable phthalonitrileterminated oligo(phthalazinone imide)s with well controlled molecular weights were prepared by varying the molar ratio of dianhydrides to diamines.FTIR

1H-NMR and elemental analysis were applied to confirm the structures of the oligomers whose molecular weights were determined by 1H-NMR analysis.The crosslinking reactions of the phthalonitrile-terminated oligomers were performed under normal pressure in the presence of 4

4-diaminodiphenylsulfone as catalyst at elevated temperatures to form the s-triazine rings-containing thermosetting oligo(phthalazinone imide)s.The oligomers possess good solubility in common aprotic solvents such as chloroform

pyridine

mcresol and N-methyl-2-pyrrolidone due to the incorporation of crank

twisted and non-coplanar phthalazinone moiety into the polymer main chain

which disorders the close packing of the intermolecular chain.However

the cured samples are insoluble in all solvents because of the formation of the heterocyclic s-triazine networks during the crosslinking reaction of the cyano groups.The thermal properties of both the oligomers and the cured oligoimides were characterized by DSC

TGA and DTG.The oligomers have high glass transition temperatures(Tgs) in the range of 200~249℃.The cured samples show no Tg from 100~400℃ for the heterocyclic s-triazine networks decrease the flexibility of polymer backbone.And they exhibit excellent thermal stability with 5% weight loss temperature up to 522~532℃

10% weight loss temperature ranging from 556℃ to 567℃ and the carbonized residue values at 800℃ in the range of 69%~74%.For the excellent thermal stability of the cured oligoimides

they can be used as high performance polymeric materials in the aerospace and base materials for high temperature composite matrix.