A Fully Bio-Based Elastomer with Ultrahigh Lignin Content and Performance Rivaling Nitrile Rubber

Achieving renewable, high-performance elastomers remains a key goal of green materials science. Here, we report a high-performance and recyclable elastomer produced directly from industrial Kraft lignin through a one-pot in situ graft copolymerization strategy. A deep eutectic solvent composed of oxalic acid and 1,6-hexanediol simultaneously dissolves lignin, provides flexible chains, and drives catalyst-free esterification at 110°C, constructing an interpenetrating rigid–flexible network that incorporates 50–75 wt.% lignin. The optimal elastomer delivers a tensile strength of 12.0 MPa, 878% elongation, and 85.1 MJ m − 3 fracture energy, rivaling or exceeding petroleum-derived nitrile butadiene rubber (3.1 MPa, 750% elongation and 11.0 MJ m − 3 ). It also offers a low dielectric constant, high electrical insulation, superior oil and abrasion resistance, efficient photothermal conversion, and infrared-induced self-healing. The material can be repeatedly reprocessed, enabling closed-loop recycling. Converting an abundant lignin by-product into a value-added elastomer thus provides a scalable route to eco-materials with broad application potential.