Synthesis and characterization of novel Schiff base polyurethanes

Eight different types of novel polyurethanes (PUs) were synthesized through the polyaddition reaction of 4,4′-(ethane-1,2-diylidenedinitrilo)diphenol and 4,4′-(pentane-1,5-diylidenedinitrilo)diphenol with four different diisocyanates: 4,4′-diphenylmethane diisocyanate, toluene 2,4-diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. The resulting PUs were soluble in polar, aprotic solvents. Structures of the diols and PUs were established with ultraviolet–visible, fluorescence, Fourier transform infrared (FTIR), 1H-NMR, and 13C-NMR spectroscopy data. FTIR and NMR spectral data indicated the disappearance of both hydroxyl and isocyanate groups in the PUs. The thermal properties were investigated with thermogravimetry and differential scanning calorimetry. The weight losses, glass transitions, onset temperatures, and crystalline melting temperatures were measured. All the PUs exhibited semicrystalline and amorphous morphologies, as indicated by X-ray diffraction. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009.