TECHNOLOGY FOR THE PREPARATION OF COPPER(II)-AMINE COMPLEXES FOR THEIR APPLICATION AS ANTI-FIRE CURRENT IN EPOXY COMPOSITIONS

Abstract

Introduction. In recent years, there has been a growing interest in metal-containing flame retardants, which are suggested to be used in reducing the fire hazard of polymers, particularly composite materials based on epoxy resins. Complex metal compounds are highly promising for creating epoxy compositions with reduced fire hazard and regulating their characteristics.
Such flame retardants can form stable metal oxides that become part of the carbonized residue during combustion, as well as catalyze polymer decomposition in the direction of increasing the yield of carbonized residue, which prevents further contact between the polymer material and the flame. Moreover, toxic intermediate aromatic compounds and benzene derivatives, which are the main components of smoke, can be converted into more stable hydrocarbon or polyaromatic compounds in the presence of metal-containing flame retardants, which leads to a decrease in smoke emission. A noticeable effect from the use of reactive metal-containing flame retardants is manifested even with a small content of them in the polymer.
Aim. To develop an effective technology for the preparation of chelated copper (II)-amine complexes, to establish
their structure, which will make it possible to predict the feasibility of their use as flame retardants for epoxy compositions.
Methods. The development of an effective technology for the synthesis of chelated copper (II)-amine complexes
included empirical selection of the ratio of the starting components, the method of their pretreatment, and the
determination of the optimal temperature and duration of the reaction. To establish the relationship between the spatial
structure of the synthesized copper (II)-amine complexes and their physicochemical properties, the crystal structure of
the chelated complexes was studied by X-ray crystallography.
Results. The copper (II)-amine complexes were synthesized by direct interaction of the corresponding Cu (II) salt with PEPA, a hardener of epoxy resins. The formation of high-quality crystals suitable for X-ray crystallographic analysis occurred after the mixture of salt and amine was kept at room temperature for several days. The chemical composition, structure, and crystallographic parameters of the synthesized chelated copper (II)-amine complexes were studied.
Conclusions. A series of chelated copper (II)-amine complexes have been synthesized using an efficient technology. It was found that in the molecules of the complexes, the Cu (II) atom forms strong coordination σ-bonds with the atoms of the N amine ligands. It has been found that copper (II)-amine complexes can simultaneously act as both epoxy resin hardeners and flame retardants. The strength of the amine retention in the complex is a crucial factor in the resistance to ignition and combustion of polymeric materials based on the epoxy amine compositions modified with copper (II)-amine complexes.