Synthesis and characterization of new optically active segmented poly(amide imide urethane)s based on different diacids via an isocyanate route

A new class of optically active poly(amide imide urethane)s (PAIUs) was synthesized via a two‐step diisocyanate route. In the first step, 4,4′‐methylenebis(phenyl isocyanate) (MDI) was reacted with different diacids to produce an isocyanate‐terminated oligo(amide imide). The chain extension of the previous hard segment with poly (ethylene glycol) diols with a molecular weight of 400 was the second step for furnishing a series of new PAIUs. N ‐Trimellitylimido‐ L ‐leucine was used as a diacid monomer for polycondensation reactions. Polymerization reactions were performed without any catalysts or with pyridine or dibutyltin dilaurate as a catalyst. The optimized reaction conditions were used for the reaction of N ‐trimellitylimido‐ L ‐isoleucine, N ‐trimellitylimido‐ L ‐methionine, N ‐trimellitylimido‐ S ‐valine, and N ‐trimellitylimido‐ L ‐phenylalanine as diacid monomers with MDI. The resulting multiblock copolymers had inherent viscosities of 0.25–0.78 dL/g. These multiblock copolymers were optically active, thermally stable, and soluble in amide‐type solvents. All these polymers were fully characterized with Fourier transform infrared spectroscopy, 1 H‐NMR and ultraviolet–visible spectroscopy, specific rotation measurements, and thermal analyses. Some structural characteristics and physical properties of these new optically active PAIUs were examined. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008