Utilization of carbon dioxide to build a basic block for polymeric materials: an isocyanate-free route to synthesize a soluble oligourea

Abstract

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.