Microwave-assisted and classical heating polycondensation reaction of bis(p-amido benzoic acid)-N-trimellitylimido-L-leucine with diisocyanates as a new method for preparation of optically active poly(amide imide)s

A new class of optically active poly(amide imide)s were synthesized via direct polycondensation reaction of diisocyanates with a chiral diacid monomer. The step-growth polymerization reactions of monomer bis(p-amido benzoic acid)-N-trimellitylimido-L-leucine (BPABTL) (5) as a diacid monomer with 4,4'-methylene bis(4-phenylisocyanate) (MDI) (6) was performed under microwave irradiation, solution polymerization under gradual heating and reflux condition in the presence of pyridine (Py), dibuthyltin dilurate (DBTDL), and triethylamine (TEA) as a catalyst and without a catalyst, respectively. The optimized polymerization conditions according to solvent and catalyst for each method were performed with tolylene-2,4-diisocyanate (TDI) (7), hexamethylene diisocyanate (HDI) (8), and isophorone diisocyanate (IPDI) (9) to produce optically active poly-(amide imide)s by the diisocyanate route. The resulting polymers have inherent viscosities in the range of 0.09-1.10 dL/g. These polymers are optically active, thermally stable, and soluble in amide type solvents. All of the above polymers were fully characterized by IR spectroscopy, H-1 NMR spectroscopy, elemental analyses, specific rotation, and thermal analyses methods. Some structural characterization and physical properties of this new optically active poly(amide imide)s are reported. (C) 2004 Wiley Periodicals, Inc.