New optically active poly(amide-imide)s derived from N,N′-(4,4-diphthaloyl)-bis-l-leucine and hydantoin derivatives: Synthesis and properties

Six new optically active poly(amide-imide)s (5a-f) were synthesized through the direct polycondensation reaction of N,N′-(4,4′-diphthaloyl)-bis-l-leucine (3) with six hydantoin derivatives (4a-f). Triphenyl phosphite (TPP)/pyridine in the presence of calcium chloride (CaCl2) and N-methyl-2-pyrrolidone (NMP) were successfully applied for direct polycondensation. The polycondensation reactions produce a series of new poly(amide-imide)s (5a-f) in high yields, and inherent viscosity between 0.42 and 0.55 dL/g. The resulting poly(amide-imide)s (5a-f) were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis (TGA and DTG), solubility test and FT-IR spectroscopy.