Catalyst-free reprocessable crosslinked biobased polybenzoxazine-polyurethane based on dynamic carbamate chemistry

The introduction of dynamic covalent chemistry into the field of polymer chemistry has resulted in a new class of network polymer materials named covalent adaptable networks (CANs). These new materials have effectively bridged two antagonistic materials, that is, conventional thermoplastic and thermoset polymers together, thanks to these dynamic exchangeable covalent bonds, making them recyclable. In this work, we report a catalyst-free reprocessable polybenzoxazine-polyurethane thermosetting system with activation of carbamate dynamic bond exchange. The curing characteristics and properties of this biobased polybenzoxazine-polyurethane network have been determined by Fourier transform infra-red (FTIR), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMA). Moreover, the tests of the recyclability of the material were successfully achieved under mild reprocess conditions (130°C, 10 min) thanks to the formation of abundant free phenolic hydroxyl groups. This work provides a promising potential for industrial applications as a new recyclable and reprocessable thermosetting polybenzoxazine material.