Synthesis of metal-containing polyurethanes from aromatic diisocyanate prepolymers

Abstract

Polyurethane-ureas and copolyurethane-ureas elastomers containing hexadentate Schiff base zinc and nickel complex in the polymer chains have been synthesized. The hexadentate Schiff base metal complexes were obtained from metal acetates and ligand which was prepared from triethylenetetramine and salicylaldehyde. Then, the polyurethane-ureas were synthesized by polymerization of hexadentate Schiff base metal complexes with aromatic diisocyanate perpolymers at different molecular weights. The progress of polymerization reaction was monitored by using infrared spectroscopy. The disappearance of isocyanate peak at 2359 cm•1 was observed when the polymerization was completed. The copolyurethane-ureas were synthesized by the reaction of metal complexes and aromatic diisocyanate prepolymers in the presence of 4, 4'-methylenebis (phenyl isocyanate) (MDI). Characterization of polyurethane-ureas and copolyurethane-ureas was carried out using IR and 1H NMR spectroscopy, elemental analysis and viscosity. The thermal properties of obtained polymers were studied by thermogravimetric analysis (TGA) and limiting oxygen index (LOI). It was found that the obtained polymers did not show liquid crystalline property, but they showed good thermal stability.