Preparation of rigid polyurethane foams catalyzed by metal-glycine and metal-alanine complexes

Abstract

In this study, rigid polyurethane foams were synthesized by using the metal-amino acid complexes as catalysts. The amino acids used were glycine and alanine, which are water soluble amino acid. Therefore, they can form complexes with metal acetate in water to give aqueous solution of metal-amino acid complexes. The advantages of this catalysts are the aqueous solution of metal-amino acid complexes do not have odor and the amino acids are non-toxic. The chemical structure of metal-amino acid complexes were characterized by using UV-visible spectroscopy, FTIR spectroscopy and mass spectrometry. Rigid polyurethane (RPUR) foams were prepared by the reaction between polymeric methanediphenyl diisocyanate and polyol at the isocyanate index of 100. The reaction times of foam formation, physical properties and mechanical properties of RPUR foams were investigated and compared with those obtained from a commercial catalyst. The results revealed copper-alanine complex was the best catalyst. Rigid polyurethane foam prepared from copper-alanine complex had comparable physical and mechanical properties to that prepared from dimethylcyclohexylamine.