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.