Dynamic Covalent Network Epoxy for Skin-Like Strain Sensors: High Resilience, Self-Adhesion, Self-Healing, and Degradability

Abstract

Epoxy vitrimers exhibit excellent self-healing and reprocessing capabilities. However, they cannot be used as flexible strain sensors to obtain stable and reliable signals due to their high modulus, poor resilience, and lack of self-adhesion. Here, a functionalized epoxy elastomer was synthesized for flexible strain sensors. Incorporating flexible long-chain structures (PMPA and PEGDGE) and moderate cross-linking densities, the elastomer achieved excellent resilience (∼100% strain recovery within 0.5 s) and skin-like softness (Young’s modulus: 16.8–96.15 kPa). Additionally, the epoxy elastomer exhibited strong adhesion to skin and various substrates. The dynamic covalent network formed via β-hydroxy ester moiety endowed the elastomer with excellent high-temperature self-healing and reprocessability. The CNT-based strain sensor presented high sensitivity (GF = 78.75), a wide sensing range (0–200% strain), and excellent cycling stability over 500 cycles. Notably, the epoxy elastomer was alcohol-degradable, ensuring environmental sustainability. A high-performance, eco-friendly flexible sensor based on epoxy vitrimers was prepared and is promising for applications in next-generation wearable electronics, robotic perception systems, and virtual reality interfaces.