Lignin-based polyurethane elastomers combining excellent mechanical properties and self-healing behavior for flexible sensing and biomedicine applications

A polyurethane elastomer is prepared via boronate–lignin nanoparticle synergy. • Lignin incorporation boosts tensile strength of polyurethane elastomer by over 500%. • It exhibits effective self-healing ability and ideal reprocessability. • It shows good biocompatibility and can serve as a flexible sensor. Conventional polyurethane elastomers face challenges in balancing mechanical properties, self-healing ability, and biosafety, along with heavy reliance on petrochemical resources. Here, we propose a strategy combining dynamic covalent crosslinking with nano-interfacial toughening to construct a lignin-based self-healing polyurethane (TPU-LNP). A dithiol-bis(boronic ester) chain extender (BDB) was synthesized to introduce reversible crosslinks into the polyurethane backbone, while nanoscale lignin particles serve as a green reinforcing phase, forming multiple hydrogen bonds and enabling stress transfer. The dynamic network and physical interfacial interactions synergistically overcome the typical trade-off between strength and self-healing efficiency. Compared with single dynamic network polyurethane (P-TPU), TPU-LNP shows > 500% increase in tensile strength while retaining 1000% elongation at break. Efficient self-healing of TPU-LNP is achieved under ambient conditions, and the tensile strength of the healed specimen is still 3.9 times that of P-TPU. Sensors fabricated with this elastomer as the flexible substrate exhibit sensitive strain-sensing capacity and can capture diverse human movements, demonstrating great application potential in wearable monitoring. In vitro and in vivo biocompatibility evaluations verify that the material possesses extremely low cytotoxicity and triggers negligible tissue inflammatory responses, indicating its adequate biosafety. This work offers a route to high-performance self-healing elastomers for biomedical and smart flexible applications. Download: Download high-res image (214KB) Download: Download full-size image