Synthesis of poly(ether ketone amide)s containing 4-aryl-2,6-diphenylpyridine moieties by a heterogeneous palladium-catalyzed polycondensation of aromatic diiodides, aromatic diamines, and carbon monoxide

New aromatic poly(ether ketone amide)s containing 4-aryl-2,6-diphenylpyridine units were prepared by the heterogeneous palladium-catalyzed carbonylative polymerization of aromatic diiodides with ether ketone units, aromatic diamines bearing pyridine groups, and carbon monoxide. Polymerizations were performed in N,N-dimethyl- acetamide (DMAc) at 120 degrees C in the presence of a magnetic nanoparticles-supported bidentate phosphine palladium complex [Fe3O4@SiO2-2P-PdCl2] as catalyst with 1,8-diazabicycle[5,4,0]-7-undecene (DBU) as base and generated poly(ether ketone amide)s with inherent viscosities up to 0.79dL/g. All the polymers were soluble in many organic solvents. These polymers showed glass transition temperatures between 219 degrees C and 257 degrees C and 10% weight loss temperatures ranging from 467 degrees C to 508 degrees C in nitrogen. These polyamides could be cast into transparent, flexible, and strong films from DMAc solution with tensile strengths of 86.4 to 113.7MPa, tensile moduli of 2.34 to 3.19GPa, and elongations at break of 5.2% to 6.9%. These polymers also exhibited good optical transparency with an ultraviolet-visible absorption cut-off wavelength in the 371 to 384-nm range. Importantly, the new heterogeneous palladium catalyst can easily be recovered from the reaction mixture by simply applying an external magnet and recycled at least 8 times without significant loss of activity. Our catalytic system not only avoids the use of an excess of PPh3 and prevents the formation of palladium black, but also solves the basic problems of palladium catalyst recovery and reuse.