Conventional polyurethanes (PUs) involve the use of isocyanates, which require hazardous and toxic phosgene for their manufacture. To tackle environmental issues as well as to meet safety and health requirements for those in PU industry and for the consumers, various routes to more friendly “green” PUs are highly desirable. The cyclic carbonate/amine addition reaction resulting in urethane segments is the actual targeted chemistry towards Non-Isocyanate PolyUrethanes (NIPUs). In this context, we have been developing different isocyanate-free strategies towards the preparation of NIPUs, and more specifically towards PolyHydroxyUrethanes (PHUs).
The first approach involves the chemical modification of α,ω-dihydroxy telechelic polymers into the α,ω-di(glycerol carbonate) parent polymers. Accordingly, poly(trimethylene carbonate) (PTMC), poly(propylene glycol) (PPG), poly(ethylene glycol) (PEG), poly(ester ether) (PEE), and poly(butadiene) (PBD), end-capped by glycerol carbonate (GC) at each terminus, have been prepared. Subsequently, using PTMC-GC2 and PPG-GC2 to demonstrate the concept, the corresponding PHUs/NIPUs have been obtained following a non-isocyanate method, namely upon ring-opening catalyst-free polyaddition of the GC moieties with a diamine.
The second pathway we have been recently investigating involves the ring-opening metathesis polymerization (ROMP) of cyclooctene using Grubbs’ second generation ruthenium catalyst in the presence of GC derivatives as chain-transfer agents. α,ω-Di(glycerol carbonate) telechelic polyolefins have thus been synthesized in a one-step approach, as precursors to the corresponding PHUs.