Preparation of rigid polyurethane foams catalyzed by copper-amine complexes prepared in water

Abstract

In this research, the catalysts for preparation of rigid polyurethane (RPUR) foams were developed in order to reduce odor as compared with dimethylcyclohexylamine (DMCHA), which has strong odor. These synthesized catalysts were copper-amine complexes, namely Cu(OAc)2(amine)2 and Cu(OAc)2(amine), where amine = ethylenediamine (en), triethylenetetramine (trien), tetraethylenepentamine (tetraen) and pantaethylenehexamine (pentane). The synthesis of copper-amine complexes was done using green chemistry approach, which used water as a solvent. The aqueous solutions of copper-amine complexes in water were obtained. These aqueous solutions could be further used in the preparation of RPUR forms without purification. Characterization of copper-amine complexes was done by using UV-visible spectroscopy, Fourier transform infrared spectroscopy and mass spectrometry. The catalytic activity was studied by investigation of the reaction times. Physical and mechanical properties of RPUR foams were studied. The data were compared with those obtained from DMCHA. The experimental results showed that the aqueous solutions of all copper-amine complexes could be easily dissolved in the starting materials of RPUR foam formulation. Cu(OAc)2(en)2 and Cu(OAc)2(trien) had high catalytic activity. Cu(OAc)2(en)2 and Cu(OAc)2(trien) gave the RPUR foams having appropiate density, good physical and mechanical properties. Therefore, Cu(OAc)2(en)2 and Cu(OAc)2(trien) were suitable catalysts for preparation of RPUR foams.