Design of high-performance bio-based polyurethane vitrimers with tunable mechanics, thermal stability, shape memory, and recyclability

The development of recyclable and sustainable polyurethanes is crucial to addressing the growing demand for high-performance materials with reduced environmental impact. Herein, we report the synthesis of castor oil-derived bio-based polyurethane (bPU) vitrimers incorporating dynamic covalent bonds through the introduction of imine and/or disulfide-containing crosslinkers. Four vitrimer formulations were systematically investigated to evaluate the role of dual dynamic bonds on thermal, mechanical, and reprocessing properties. The resulting networks exhibited high gel content and strong solvent resistance, with high tensile strengths. Dynamic mechanical analysis revealed that imine-containing samples showed superior stress relaxation, enabling efficient network rearrangement. In contrast, disulfide incorporation improved dimensional stability and thermal resistance, while dual-crosslinked bPU-T-V exhibited balanced performance. All vitrimers demonstrated excellent chemical degradability in acidic environments, enabling potential closed-loop recycling, and bPU-T-V displayed pronounced shape memory behavior. The resulting materials demonstrate a robust and versatile platform for renewable, reprocessable thermosets suitable for advanced coatings, adhesives, and composite applications, supporting the transition toward circular and environmentally responsible polymer systems.