The development of controllable complex curing agents for epoxy resins. I. Preparation, characterization, and storage behavior of transition metal-diamine complexes

A series of complexes incorporating diamine (o-phenylene diamine and 2-aminobcnzylaminc-OPD and 2-ABA respectively) ligands and containing the acetato and chloro transition metal salts of Ni and Cu has been prepared and characterized using elemental analysis and spectroscopic methods. Infrared data show that complexation of the amino nitrogen atoms occurs to a high degree. The same curing agents have been incorporated into two commercial epoxy resins recognized as "industry standards" (MY721 and MY750), and their cure properties and shelf life assessed alongside commercial curative systems. The current work demonstrates that while complexes based on copper(II) and nickel(II) and containing OPD ligands may be prepared and incorporated into commercial epoxy resins, there are some advantages associated with using 2-ABA (as the diamine ligand) due to the higher complex solubility and better processing characteristics that it imparts to the formulated system. In general, the 2-ABA based complexes disperse well within commercial epoxy systems and display good storage stability over prolonged periods of time (up to 67 days at ambient temperature). Work continues to examine the thermal and mechanical characteristics of commercial epoxy resins cured using these complexes. (C) 2001 John Wiley & Sons, Inc.