Recyclable palladium-catalyzed synthesis of new cardo poly(amide-imide)s from diiodo imides, aromatic diamines containing cardo groups, and carbon monoxide

High molecular weight poly(amide-imide)s containing cardo structures were readily prepared by a supported palladium-catalyzed carbonylation polymerization of diiodo imide monomers, aromatic diamines containing cardo groups, and carbon monoxide. Polycondensation reaction proceeded effectively in N,N-dimethylacetamide (DMAc) at 100 degrees C in the presence of a bidentate phosphino-modified magnetic nanoparticles-anchored palladium complex [2P-Fe3O4@SiO2-PdCl2] as catalyst and 1,8-diazabicyclo[5,4,0]-7-undecene (DBU) as base under 1 atm of CO, yielding a series of new poly(amide-imide)s with inherent viscosities up to 0.95 dL/g. All the polymers obtained were easily soluble in some strong polar aprotic organic solvents and could be cast into transparent, flexible and tough films from their DMAc solutions. These cardo poly(amide-imide)s displayed high thermal stability with the glass transition temperatures ranging from 237 to 265 degrees C, the temperatures at 5% weight loss ranging from 433 to 475 degrees C in nitrogen. These PAI films also exhibited good mechanical behavior and high optical transparency. The present method provides the flexibility of incorporating different ratios of imide and amide groups in the polymer backbone in a controlled manner and eliminates the possibility of postpolymerization curing due to the imide moiety being preformed. Importantly, the supported palladium catalyst can be conveniently separated from the polymer by simply using an external magnetic field and recycled at least 8 times without apparent loss of catalytic efficiency.