Heat Resistant Poly(amide-imide)s Derived from N,N′-(4,4′-Pyromellitoyl)-bis-L-phenyl Acetic Acid and Aromatic Diamines: Synthesis and Properties

Six new heat resistant and optically active poly(amide-imide)s 5a–f were prepared by the direct polycondensation reaction of N,N′-(4,4′-pyromellitoyl)-bis-L-phenyl acetic acid 3 with various different diamines 4a–f in a medium consisting of triphenyl phosphite, N-methyl-2-pyrrolidone, pyridine and calcium chloride. These polymers were obtained in high yields and had inherent viscosities between 0.35–0.50 dL/g. The resulting polymers were characterized by viscosity measurements, thermal gravimetric analysis (TGA and DTG), differential scanning calorimeter (DSC), solubility test, specific rotation, FT-IR and 1H NMR spectroscopy. N,N′-(4,4′-pyromellitoyl)-bis-L-phenyl acetic acid 3 was prepared by an one-stop reaction of pyromellitic anhydride 1 with L-phenyl acetic acid 3 in acetic acid solution in quantitative yield.