From High Strength to High Sensitivity: Engineering Dynamic Polyurethane Elastomers with Mechanochromism and Bimodal Sensing Functions

Polyurethane elastomers are attractive for flexible protection, wearable devices, and intelligent sensing because they combine good mechanical performance, structural tunability, and processability. A persistent difficulty, however, is how to obtain high strength and toughness without sacrificing resilience. Here, we construct a dynamic polyurethane elastomer (SPU-ID) by introducing disulfide bonds and hydrogen-bond interactions into a multilevel amide network. By varying the disulfide bond content, we identify a threshold-like effect on microphase structure and strain-induced crystallization. Among the compositions studied, SPU-I 0.75 D 0.25 shows the most balanced performance, with a tensile strength of 46.5 MPa, an elongation at break of 1800%, and excellent resilience. The elastomer also exhibits a visible and reversible blue color change under large deformation, together with good healability and recyclability after repeated thermal pressing. These features make SPU-ID a suitable elastomer platform for further sensing applications. After the ionic liquid is introduced, the material retains its strain-responsive color change and simultaneously gains electrical signal output, enabling a polyurethane-based color–electrical bimodal sensing platform that demonstrates the feasibility of combined electrical and color outputs at low temperature.