Synthesis of polyurea from 1,6-hexanediamine with CO2 through a two-step polymerization

摘要

Activation and transformation of CO2 is one of the important issues in the field of green and sustainable chemistry. Herein, CO2 as a carbonoxygen resource was converted to CO2-polyurea with 1,6-hexanediamine through a two-step polymerization. The reaction parameters such as temperature, pressure and reaction time were examined; and several kinds of catalysts were screened in the absence and presence of NMP solvent. The formed oligomer and the final polyurea were characterized by FT-IR, VT-DRIFTS, NMR, XRD, AFM and their thermal properties were examined by TGA and DSC. It was confirmed that the final polyurea has a high thermal stability; the melting temperature is 269℃ and the decomposition temperature is above 300℃. It is a brittle polymer with a tensile strength of 18.35 MPa at break length of 1.64%. The polyurea has a stronger solvent resistance due to the ordered hydrogen bond in structure. The average molecular weight should be enhanced in the postpolymerization as the appearance, hydrogen bond intensity, crystallinity, melting point and the thermal stability changed largely compared to the oligomer. The present work provides a new kind of polyurea, it is expected to have a wide application in the field of polymer materials.