Mehdi Hatami

N,N′-Pyromellitoyl-bis-L-(3,4-dihydroxyphenyl)alanine was synthesized, as a new diacid monomer, from condensation reaction of l-dopa and pyromellitic anhydride. Polycondensation of this chiral monomer with the commercially available 4,4′-diaminodiphenylsulfone was achieved by using triphenylphosphite, as coupling agent, and calcium chloride, as dehydrating agent, in a mixture of N-methyl-2-pyrolidone and pyridine, giving a fairly high yield of a novel optically active poly(amide-imide) (PAI). This catechol containing PAI shows excellent adhesion to carboxylated carbon nanotubes, as forcing it to adopt a semi-crystalline structure in the interface with the nanotubes and thereby results in formation of a thermally stable and nearly homogeneous nanocomposite. FT-IR study revealed that much of this adhesion arises from H-bonding of the carboxylated nanotubes with the carbonyl groups of the PAI. The uniform distribution of the nanotubes in the PAI matrix was confirmed by FE-SEM and TEM micrographs of their nanocomposite. Thermogravimetric analysis of the PAI and its nanocomposites with 5, 10, and 15 wt% of carboxylated carbon nanotubes indicates that their decomposition occur in the temperature range of 347–365 °C. The limiting oxygen indices for the PAI and its nanocomposites were found to be in the range of 37.9–43.1. The polymer and its nanocomposites were characterized by additional techniques.