Synthesis of Polyurea via the Addition of Carbon Dioxide to a Diamine Catalyzed by Organic and Inorganic Bases

The synthesis of polyurea via the addition of carbon dioxide (CO2) to a diamine of 4,7,10-trioxa-1,13-tridecanediamine (TOTDDA) was investigated by using organic and inorganic base catalysts. It was found that 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was the most active among the catalysts examined. The influence of CO2 pressure, temperature, and reaction time was examined for the DBU-catalyzed polyurea synthesis. The reaction mixture was analyzed by in situ high-pressure attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) under reaction conditions, and possible reaction mechanisms, in which DBU can activate both CO2 and TOTDDA, were proposed. Physicochemical properties of polyurea materials synthesized were examined by several techniques. In addition, the catalytic performance of DBU was further examined for the addition of CO2 to other different diamine compounds.