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.

A high‐performance self‐healing polyurea material based on exchangeable aromatic disulfide

“…Meanwhile the spectra show new characteristic peaks at 3330, 1556, and 1637 cm −1 , which can be attributed to the stretching vibration and bending vibration of NH, and the stretching vibration of CO, respectively. The appearance of all these characteristic peaks proves the formation of urea bond and the successfully synthesis of SPU samples, identical to literature report 13,14 . In addition, the characteristic peaks at 2970 and 2870 cm −1 are attributed to the asymmetric and symmetric stretching vibrations of the methylene group, respectively, 6 and the strong stretching vibration peak at 1089 cm −1 could be assigned to the COC groups in PPG chains.…”

Isocyanate-Free Polyurea Synthesis via Ru-Catalyzed Carbene Insertion into the N–H Bonds of Urea

“…The most promising route currently utilizes amines and carbonates (Scheme 1d) as precursors with low toxicity. 12,13 Interestingly, the use of (transition-metal) catalysis to arrive at polyurea and polyurethane structures has not been developed as much. Transition-metal-catalyzed polymerizations using diazo compounds provide a powerful alternative synthetic tool to otherwise difficult to access structures.…”

“…The polycondensation route (Scheme b) releases side products during curing which limits industrial usage, which in the case of ring-opening is limited by the high temperatures required (Scheme c). The most promising route currently utilizes amines and carbonates (Scheme d) as precursors with low toxicity. , …”

Non-Isocyanate Aliphatic–Aromatic Poly(carbonate-urethane)s—An Insight into Transurethanization Reactions and Structure–Property Relationships

“…In contrast, the NIPUs’ precursors are not phosgene-based and are not moisture sensitive. Furthermore, they can be obtained from carbon dioxide—a greenhouse gas that is easily accessible [ 5 , 6 ].…”

“…Carbamates are commonly synthesized via the methoxycarbonylation of aliphatic/aromatic diamines with dimethyl carbonate [ 28 , 29 , 30 ] or aminolysis of ethylene carbonate using aliphatic diamines [ 6 , 22 , 31 , 32 ]. The products of these reactions are bis(methyl carbamate)s (BMC) or bis(2-hydroxyalkyl carbamate)s, respectively.…”