Deep Eutectic Solvent-Mediated Conductive Polyurethane Elastomers with Synergistic Self-Healing, Adhesion, and Wide-Temperature Sensing for Wearable Health Monitoring

Abstract

Conductive elastomers have attracted considerable interest for electronic skin and wearable health-monitoring devices. Although soft and self-healing polyurethane elastomers have been extensively developed, the simultaneous integration of mechanical robustness, stable ionic conductivity, recovery of both mechanical and electrical functions, interfacial adhesion, cyclic durability, and reliable sensing over a wide temperature range remains challenging. In particular, increasing polymer-chain mobility may promote ion transport and interfacial healing but can compromise mechanical strength and dimensional stability, whereas reinforcement of the polymer network may restrict molecular diffusion and ionic migration. To address these trade-offs, we introduce a ChCl/AA deep eutectic solvent (DES) into a dynamic polyurethane (PU) network through solvent exchange. The optimized PU-DES-4 exhibits a tensile strength of 2.71 MPa and an ionic conductivity of 3.81 × 10–2 S m–1 at 25 °C. Its self-healing behavior is strongly temperature dependent: mechanical recovery exceeds 90% after healing at 60 °C for 3 h but reaches approximately 50% and 65% after 12 h at 25 and 37 °C, respectively. The material also shows spontaneous room-temperature adhesion, with a metal lap-shear strength of approximately 138 kPa without thermal activation; this value increases to 2.67 MPa after thermal conditioning at 60 °C for 30 min. In addition, PU-DES-4 maintains stable sensing performance from −20 to 50 °C and supports wearable motion and physiological signal monitoring. These results demonstrate a DES-mediated strategy for balancing mechanical, ionic, interfacial, and sensing functions while also identifying mild-temperature healing and quantitative long-term retention as areas requiring further optimization.