Chemically Recyclable, High Molar Mass Polyoxazolidinones via Ring Opening Metathesis Polymerization

The development of robust methods for the synthesis of chemically recyclable polymers with tunable properties is necessary for the design of next-generation materials. Polyoxazolidinones (POxa) – polymers with five-membered urethanes in their backbones – are an attractive target because they are strongly polar and have high thermal stability, but existing step-growth syntheses limit molar masses and chemical recyclability to monomer is rare. Herein, we report the synthesis of high molar mass POxa via ring opening metathesis polymerization of oxazolidinone-fused cyclooctenes. These novel polymers show <5% mass loss up to 382–411 °C and have tunable glass transition temperatures (14–56 °C) controlled by side chain structure. We demonstrate facile chemical recycling to monomer and re-polymerization despite moderately high monomer ring strain energies, which we hypothesize is facilitated by the conformational restriction introduced by the fused oxazoli-dinone ring. This method represents the first chain growth synthesis of POxa and provides a versatile platform for the study and application of this emerging subclass of polyurethanes.