Environmentally Friendly Synthesis of Urea-Free Poly(carbonate-urethane) Elastomers

Abstract

This work presents an eco-friendly synthetic pathway toward non-isocyanate poly(carbonate-urethane)s (NIPCUs) obtained from carbon dioxide and its simple derivatives─organic carbonates. Bis(hydroxyalkyl carbamate)s synthesized from ethylene carbonate and appropriate α,ω-diamines were used as polyurethane hard segment precursors while oligocarbonate diols as soft segment ones. The structures and properties of the obtained NIPCUs were explored by means of 1H NMR, 13C NMR, and FT-IR spectroscopies, MALDI-ToF mass spectrometry, DSC, and mechanical testing. Based on spectroscopic data as well as model reactions, it was demonstrated that the formation of the urea bonds was suppressed due to the presence of carbonate moieties. The reaction of urea bonds with carbonate residues led to urethane group formation. In addition, the influence of the polyurethane structure on the mechanical and thermal properties of the obtained polymers was studied. The obtained NIPCUs exhibited mechanical properties comparable to conventional polyurethane elastomers (e.g., a tensile strength of 32 MPa and an elongation at break of 800%). The described synthetic route is an straightforward way toward the replacement of conventional polyurethanes with environmentally friendly ones.