A series of poly(aryl ether ketone) polymers (m-PAEK-CN) containing phthalonitrile were synthesized by a direct solution polycondensation and characterized by Fourier-transform infrared spectroscopy and hydrogen nuclear magnetic resonance. Thermal crosslinking of m-PAEK-CN, catalyzed by p-BAPS, was then performed via heating their films up to 350 degrees C. Dynamic rheology results showed that the rate of diamine-catalyzed crosslink reaction could be easily controlled by varying the content of cyano groups in the polymer. The uncured synthesized polymers had good solubility, whereas the cured ones became insoluble in common organic solvents. Spectra measurement demonstrated the trimerization reaction of terminal cyano groups to form triazine rings. The resulting cured samples had higher glass transition temperatures, better thermal, and thermo-oxidative stability with high char yield than the uncured ones. Gel content measurements demonstrated that the cured polymers had high crosslinking density with significantly high gel content over 96.0%. Thermal mechanical analysis indicated that the cured phthalonitrile resins possessed excellent thermal mechanical properties and dimensional stability at increased temperatures. The tensile modulus and strength of the cured m-PAEK-CN increased up to 2101-2104 MPa and 96-100 MPa, respectively, which were about 21-23% and 32-56% higher than the uncured ones'. This kind of phthalonitrile resins may be used as a candidate for high-performance polymeric film materials. (C) 2015 Society of Plastics Engineers