Supramolecular Integration Promotes Sustainable Elastomers with Enhanced Toughness and Fluorescence

ABSTRACT Fluorescent elastomers that integrate high toughness, sustainability, and strong emission are highly sought after but remain difficult to achieve due to competing molecular design constraints. Here, we report a supramolecular integration (SMI) strategy that co‐grafts 1,3‐diaminopropane (DAP) and fluorescent 5‐amino‐2‐(4‐aminophenyl)benzimidazole (PABZ) fragments onto polyurethane chains. The resulting elastomer achieves an outstanding tensile toughness of 650 MJ m −3 and exhibits uniform blue fluorescence, along with self‐healing, recyclability, and degradability. Experimental results and density functional theory calculations reveal that mismatched supramolecular interactions between DAP and PABZ enhance energy dissipation and suppress chromophore aggregation, enabling simultaneous improvements in mechanical and optical performance. Notably, the spent elastomers can be upcycled into ionic skins by incorporating ionic liquids. The upcycled materials exhibit a favorable balance of mechanical resilience and ionic conductivity, making them ideal for wearable strain sensing, with rapid response (0.20 s) and excellent durability over 5000 cycles. In addition, strong dielectric loss enables efficient electromagnetic wave absorption, with reflection loss values below –10 dB in the 10.5–12.0 GHz range, corresponding to over 99% attenuation. This work establishes a versatile approach for constructing multifunctional elastomers with integrated mechanical, optical, and electronic performance, while offering sustainable end‐of‐life utility through upcycling.