Depolymerizable Thermosetting Dielectric Elastomers Toughened by Sacrificial Hydrogen Bonds for Sustainable Capacitive Strain‐Sensor

Abstract The development of sustainable capacitive strain‐sensors necessitates dielectric elastomers that integrate mechanical robustness and closed‐loop recyclability. Herein, a self‐healing thermosetting elastomer (PIT) is designed that simultaneously achieves depolymerizability and high toughness through a dual‐crosslinking architecture combining triazine‐based dynamic covalent linkages and supramolecular hydrogen bonds. The dynamic nucleophilic aromatic substitution enables closed‐loop chemical recycling, while the sacrificial hydrogen bonding dissipates energy to enhance mechanical toughness. The electron‐deficient triazine structure confers enhanced dielectric properties (κ = 5.94 at 100 kHz), surpassing common silicone‐based counterparts (e.g., silicon rubber, κ<3). Capitalizing on these attributes, a recyclable capacitive strain sensor is pioneered by assembling PIT dielectric with liquid metal electrodes. The device demonstrates superior performance metrics, including broad detection range (1%‐250% strain) with high sensitivity (gauge factor = 0.98), mechanical reliability (>500 cycles), and full‐component recyclability. Real‐time human motion monitoring validates practical functionality, while controlled depolymerization regenerates pristine materials for sensor re‐fabrication. This work presents a material design paradigm and sustainable manufacturing strategy for eco‐conscious flexible electronics.