Synthesis and characterization of new optically active poly(amide-imide)s derived from N,N′-(pyromellitoyl) bis-L-tyrosine and various diamines

Five new optically active poly(amide-imide)s(PAIs) 5a–e were prepared by direct polycondensation reaction of N,N′- (pyromellitoyl) bis-L-tyrosine 3 as chiral dicarboxylic acid with various aromatic diamines 4a–e. Triphenylphosphite(TPP)/pyridine(py) in the presence of calcium chloride (CaCl2) and N-methyl-2-pyrrolidone (NMP) were successfully applied to direct polycondensation reaction. The resulting new polymers were obtained in good yields with inherent viscosities ranging between 0.48 dL/g and 0.6 dL/g. They were analyzed with a C.H.N. elemental analyzer, FTIR, 1H-NMR, UV-VIS spectroscopy and polarimeter (specific rotation measurement, [α]D25). Thermogravimetric analysis (TGA) indicated that the residual weight percentage of polymers at 600 °C were between 48.66 % and 64.21 %, which showed their thermal stability. These polymers are attractive to be used as packing materials in chromatography columns for separation of enantiomers.