Synthesis of epoxy polymer using Schiff's base metal complexes as crosslinking agents

Abstract

Nickel and zinc hexadentate Schiff's base metal complexes have been synthesized and used as crosslinking agents for the synthesis of metal-containing epoxy polymers. The metal complexes were obtained from metal acetates and ligand which was prepared from triethylenetetramine and salicylaldehyde. These metal complexes were characterized by elemental analysis, IR spectroscopy, 1H NMR, 13C NMR, mass spectrometry and X-ray crystallography. Crosslinking of diglycidyl ether of bisphenol-A (DGEBA) with the metal complexes and using tetrabutylammoniumhydroxide (Bu4NOH) as a catalyst gave the metal-containing epoxy polymers. The properties of metal-containing epoxy polymers were studied by using dynamic mechanical analysis (DMA), differential scaning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile testing. Ni-containing epoxy polymer obtained from the ratio of NiL:DGEBA:Bu4HOH = 1:10:0.2 showed good thermal stability with the 2.3% weight loss of upon heating at 250 ํC for 48 hours and tensile strength up to 45 N/mm2. In comparison to DGEBA-diethylenetriamine system, the metal-containing epoxy polymers showed higher thermal stability. In comparison to the crosslinking with maleic anhydride, the crosslinking with the metal complexes could proceed at lower temperature while the resulting polymers had comparable thermal stability.