Mechanochemistry upcycling of thermoset polyurethane foams towards high-performance polyurethane-based ion-conductive...

Thermosetting polyurethane (PU) foam is indispensable in modern society, yet the recycling of post-consumer PU foam presents a growing environmental challenge. Recently, solid-state ion-conductive elastomers have attracted interest as potential materials for use in wearable sensors and energy harvesting systems. Herein, an efficient mechanochemical approach was developed for the upcycling of thermoset PU foam into high-value materials. We demonstrated that incorporating ionic liquid facilitated the thermally induced rearrangement of the PU network, leading to the formation of transparent and flexible PU-based ion-conductive elastomer. The obtained material exhibited a tensile strength of 10.6 MPa, an elongation at break of 297.3 %, and an ionic conductivity of 3.32 × 10^-5 mS/cm. Furthermore, it displayed elastic recovery, fatigue resistance, tear resistance, solvent resistance, and reprocessability. A resistive strain sensor fabricated from this PU-based ion-conductive elastomer exhibited high sensitivity (with a gauge factor of 1.43) within a strain range of 1-200 %, and proved capable of monitoring joint movements, such as those of the fingers, elbows, and knees. Furthermore, the diverse intermolecular interactions on the surface of the elastomer contributed to its good underwater adhesion capability. This study proposed a novel and cost-effective strategy for the end-of-life management of thermoset PU foam, offering promising potential for the development of next-generation solid-state ion-conductive elastomer materials.