Synthesis and characterization of novel optically active poly(imide-urethane)s derived from N,N′-(pyromellitoyl)-bis-(L-leucine) diisocyanate and aromatic diols

N,N'-(Pyromellitoyl)-bis-(L-leucine) diacid was reacted with ethyl chloroformate in the presence of triethylamine followed by reaction with activated sodium azide and gave N,N'-(pyromellitoyl)-bis-(L-leucine) diacylazide in high yield. This diacylazide was heated in dry benzene and gave the unstable N,N'-(pyromellitoyl)-bis-(L-leucine) diisocyanate (5) in quantitative yield. Thus, diisocyanate 5 was generated in situ and polycondensation reaction of this monomer with several aromatic diols, such as 4,4'-dihydroxybiphenyl, 1,4-hydroquinone, bisphenol A, phenolphthalein and 1,4-dihydroxyanthraquinone, was performed in dry toluene under refluxing in the presence of 1,4-diazabicyclo[2.2.2]octane (triethylenediamine) as a catalyst. The polymerization reactions proceeded within 48 h, producing a series of optically active poly(imide-urethane)s with good yield and moderate inherent viscosity in the range 0.18-0.28 dl g(-1). All of the above polymers were fully characterized by infrared spectra, elemental analyses and specific rotation. Some structural characterization and physical properties of these optically active poly(imide-urethane)s are reported (C) 2003 Society of Chemical Industry.