Synthesis and properties of novel optically active poly(amide imide urethane) thermoplastic elastomers by the reaction of a L-leucine based diacid chain extender and PEG-terminated MDI

Abstract

A new class of optically active poly(amide imide urethane) (PAIU) thermoplastic elastomers was synthesized via the reaction of NCO-terminated polyether polyols with an imide containing optically active amino acid-based dicarboxylic acid chain extender via two-step diisocyanate route. In the first step 4,4′-methylene-bis-(4-phenylisocyanate) (MDI) (6) was reacted with polyethyleneglycol-diols (PEG)s such as PEG-400, PEG-600, PEG-1000, and PEG-2000 to produce the NCO-terminated polyether soft segment. The chain extension of the above soft segment with bis(p-amido benzoic acid)-N-trimellitylimido-L- leucine (BPABTL) (5) was the second step to furnish a series of new optically active PAIUs. The PAIUs were characterized by conventional methods, and their physical properties such as solution viscosity, solubility, and thermal behaviour were studied. The copolymerization reactions were performed in the presence of triethylamine (TEA), pyridine (Py), dibutyltin dilurate (DBTDL), and no catalyst, respectively. The resulting multiblock copolymers had inherent viscosities in the range of 0.12-0.55 dL/g. These copolymers are optically active, thermally stable and soluble in amide-type solvents. Some structural characterization and physical properties of these new optically active PAIU thermoplastic elastomers are reported.