Novel optically active poly(amide-imide)s from N-trimellitylimido-S-valine and aromatic diamines by direct polycondensation reaction

N-Trimellitylimido-S-valine 3 was prepared from the reaction of trimellitic anhydride with (S)-(+)-valine(2-amino-3-methylbutyric acid) 2 in acetic acid solution at refluxing temperature. The direct polycondensation reaction of the monomer imide-diacid 3 with 1,4-phenylenediamine 4a, diaminodiphenylmethane 4b, 4,4'-diaminediphenylsulphone 4c, diaminodiphenylether 4d, 1,5-naphthalenediamine 4e, 2,4-diaminotoluene 4f and 1,3-phenylenediamine 4g, was carried out in a medium consisting of triphenyl phosphite, N-methyl-2-pyrolidone (NMP), pyridine, and calcium chloride. The polycondensation was performed under two different conditions. In one method the reaction mixture was stirred at room temperature in NMP solution and then it was heated at 60degreesC, 90degreesC, and finally at 130degreesC for different periods of time and the other method the reaction mixture was refluxed only for 1 min in the same solvent. The resulting poly(amide-imide)s PAIs having inherent viscosities 0.15-0.73 dL/g were obtained in high yield. All of the above compounds were fully characterized by IR, elemental analyses, and specific rotation. Some structural characterizations and physical properties of this new optically active PAIs are reported.