PREPARATION AND PROPERTIES OF POLY(AMIDE-IMIDE)S DERIVED FROM TRIMELLITIC ANHYDRIDE, ALPHA-AMINO-ACIDS, AND AROMATIC DIAMINES

Four dicarboxylic acids containing one preformed imide ring were prepared by condensation of trimellitic anhydride with alpha-amino acids such as glycine, DL-alanine, DL-valine, and DL-leucine. These diacids were subsequently directly polycondensated with various aromatic diamines using triphenyl phosphite (TPP) and pyridine as condensing agents in N-methyl-2-pyrrolidone (NMP) containing calcium chloride, producing various aliphatic-aromatic poly(amide-imide)s with pendant alkyl groups. The resultant polymers have inherent viscosities in the range of 0,5 8 - 2,15 dL/g and were amorphous, as revealed by wide-angle X-ray diffractograms. All polymers were readily soluble in a variety of solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and NMP, and could be cast from their DMAc solutions into transparent, flexible, and tough films. All poly(amide-imide)s showed clear glass transition temperatures in the range of 181 - 313-degrees-C on the heating traces of differential scanning calorimetry (DSC). Almost all the poly(amide-imide)s exhibited no appreciable decomposition below 370-degrees-C, with 100% weight loss being recorded above 400-degrees-C in nitrogen and air. The polymers with larger side chain attached exhibited higher solubility, but lower glass transition temperature and initial decomposition temperature.