Synthesis of thermally stable polyureas and poly(urea-imide)s containing schiff base metal complexes

Abstract

Hexadentate Schiff base zinc and nickel complexes were synthesized and used for the synthesis of metal-containing polymers. Polyureas were synthesized by reacting MNapth2trien with diisocyanates, namely 4,4'-diphenylmethane diisocyanate (MDI) and isophorone diisocyanate (IPDI). Copolyureas and poly(urethane-urea)s were synthesized from MNapth2trien/diisocyanates/diamines and MNapth2trien/diisocyanates/dialcohols, respectively. The diamines and dialcohols employed were m-xylylenediamine, (m-XDA) and 1,6-hexamethylenediamine (HMDA), 2,2-bis(4-Hydroxyphenyl)propane (BPO) and 1,6-hexamethylenediol (HDO). Poly(urea-imide)s were obtained by synthesis of metal-containing isocyanate-terminated polyurea prepolymers from the reaction between MNapth2trien and excess diisocyanates, which could then undergo further reaction with different dianhydrides. The dianhydrides employed were pyromellitic dianhydride (PMDA) and benzophenone-3,3́,4,4́-tetracarboxylic dianhydride (BTDA). Metal-containing polymers were characterized by infrared spectroscopy (IR), proton nuclear magnetic resonance spectroscopy (1H NMR), elemental analysis, X-ray diffraction (XRD), solubility and viscosity. Thermal properties of the polymers were investigated by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). It was found that the metal-containing polymers showed good thermal stability and solubility.