Synthesis of polyurethane-ureas containing nickel and zinc 4,4'-dihydroxysaltrien complexes

Abstract

4,4’-Dihydroxysaltrien zinc and nickel complexes (ML, where M = Zn and Ni) were synthesized from the reaction between 2,4-dihydroxybenzaldehyde, metal (II) acetate and triethylenetetramine at the mole ratio of 2:1:1. These metal complexes were characterized by IR, ¹H NMR, ¹³C NMR spectroscopy and elemental analysis. The metal complexes were used for the synthesis of polyurethane-ureas and copolyurethane-ureas. Polyurethane-ureas were synthesized from the polymerization reaction of ML with different diisocyanates, namely 4,4’-diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPD), poly(1,4-butanediol) toluene-2,4-diisocyanate terminated prepolymer (MW 900, PB900) and poly(propylene glycol) toluene-2,4-diisocyanate terminated prepolymer (MW 1000, PP1000). Copolyurethane-ureas were synthesized by polymerization reaction between ML, MDI and m-xylylenediamine. Metal-containing polymers were characterized by IR, NMR, elemental analysis, solubility and viscometry. Their thermal properties were studied by thermogravimetric analysis (TGA). Flammability of polymers was measured by limiting oxygen index (LOI). It was found that nickel-containing polymers show higher thermal stability than zinc-containing polymers. Thermal stability of copolyurethane-ureas was improved upon the addition of m-xylylenediamine in the polymerization.