Utilization of carbon dioxide to build a basic block for polymeric materials: an isocyanate-free route to synthesize a soluble oligourea†
A water soluble oligourea was synthesized by an isocyanate-free route from carbon dioxide and diamine in the absence of any organic solvents or additives. The chemical structure of the product was confirmed by FTIR and 13C NMR analysis, and the average molecular weight was estimated with MALDI-TOF MS. The weight average molecular weight of the obtained oligourea is about 2210 Da reacting under 180 °C and 11 MPa for 12 h. Moreover, the prepared oligourea has a moderate thermo-stability, it has an initial decomposition temperature at ∼220 °C and a melting temperature of 110 °C, as confirmed by TGA and DSC. As a soluble oligomer, it could be used as a building block to synthesize CO2-based polymeric materials due to it possessing a chemically active amino end group. For example, foaming plastics, greases, spun fibers and high strength polymer materials may be fabricated by reaction of the oligomer with a chain extender like a diisocyanate, diester or diacid.