Synthesis and characterization of new aromatic poly(amide-imide-urea)s derived from bis(4-trimellitimidophenyl) urea and various aromatic diamines

New aromatic poly(amide-imide-urea)s with enhanced thermal stability and high inherent viscosities were synthesized from a new bis(4-trimellitimidophenyl) urea (I) and aromatic diamines. The bis(4-trimellitimidophenyl) urea (1) was readily obtained by the condensation reaction of bis(4-aminophenyl) urea with trimellitic anhydride. Polymers were prepared by direct polycondensation reaction using triphenyl phosphite in N-methyl-2-pyrrolidone (NMP)/pyridine solution containing dissolved CaCl2. The obtained poly(amide-imide-urea)s showed high thermostability. Their decomposition temperatures at 10% weight loss in nitrogen atmosphere were above 515degreesC and the anaerobic char yield at 800degreesC ranged from 45 to 65%. Almost all the poly(amide-imide-urea)s showed high glass transition temperature above 205degreesC by differential scanning calorimetry (DSC) measurements. These polymers were readily soluble in various organic solvents and could be cast into transparent, tough, and flexible films.