Synthesis and characterization of new rigid‐rod and organosoluble poly(amide–imide)s based on 1,4‐bis(trimellitimido)‐2,3,5,6‐tetramethylbenzene

A series of new aromatic poly(amide-imide)s (PAIs) was synthesized by triphenyl phosphite-activated polycondensation of the diimide- diacid, 1,4-bis(trimel- litimido)-2,3,5,6-tetramethylbenzene (I), with various aromatic diamines in a medium consisting of N-methyl-2-pyrrolidone (NMP), pyridine, and calcium chloride. The PAIs had inherent viscosities of 0.82-2.43 dL/g. The diimide- diacid monomer (I) was pre- pared from 2,3,5,6-tetramethyl-p-phenylenediamine with trimellitic anhydride (TMA). Most of the resulting polymers showed an amorphous nature and were readily soluble in a variety of organic solvents including NMP, N,N-dimethylacetamide (DMAc), and N,N-dimethylformamide (DMF). Transparent, flexible, and tough films of these poly- mers could be cast from DMAc solutions. Their cast films had tensile strengths ranging from 80 to 95 MPa, elongation at break from 10 to 45%, and initial modulus from 2.01 to 2.50 GPa. The 10% weight loss temperatures of these polymers were above 510°C in nitrogen. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1162-1170, 2000