Preparation of rigid polyurethane foams catalyzed by metal-valine and metal-arginine complexes

Abstract

This research studied new catalysts for rigid polyurethane foam (RPUR foam) preparation, namely metal-amino acid complexes, which are odorless and low toxicity. The metal-amino acid complexes synthesized were Cu(OAc)(Val), Cu(OAc)(Arg), Zn(OAc)(Val), Zn(OAc)(Arg), Zn(OAc)(Ser) and Zn(OAc)(Ile); where OAc = acetate, Val = valine, Arg = arginine, Ser = serine and Ile = isoleucine. The synthesis was done to obtain aqueous solution of metal-amino acid complexes in water. These metal-amino acid complexes were used as catalysts in the preparation of rigid polyurethane foams without purification. Characterization of zinc-amino acid complexes was done using mass spectrometry and FTIR spectroscopy. The catalytic activity of metal-amino acid complexes was studied by investigation of the reaction time of the foam formation. Physical and mechanical properties of RPUR foams were investigated. The results were compared with those catalyzed by dimethylcyclohexylamine (DMCHA), which is a commercial catalyst. The experimental results Zn(OAc)(Val) showed the best catalytic activity among all metal-amino acid complexes. Zn(OAc)(Val) gave polyurethane foam having density, physical and mechanical properties similar to that catalyzed by dimethylcyclohexylamine.