Early Damage Detection in Cinnamoyl‐Functionalized Shape Memory Epoxy Through Mechanochemical Activation

Abstract

ABSTRACT Shape memory epoxy (SMP) networks combine high mechanical robustness with thermally triggered shape recovery; however, integrating mechanochemical sensing while preserving shape memory performance remains challenging due to limited force transfer within highly crosslinked networks. Here, a mechanophore‐functionalized SMP is developed to enable self‐sensing through fluorescence activation under deformation. A cinnamoyl‐based mechanophore containing primary amine groups is synthesized, photodimerized under UV irradiation, and covalently integrated into the epoxy network as an additional reactive crosslinker. This strategy incorporates mechanochemically active linkages directly into the crosslinked epoxy network. Mechanical characterization shows that mechanophore incorporation increases the storage modulus from 2.48 to 3.39 GPa, the crosslink density from 0.61 × 10 −3 to 0.97 × 10 −3 mol cm −3 , and the glass transition temperature from 52.7°C to 62.5°C, while maintaining the overall thermomechanical behavior of the epoxy network. In situ fluorescence tensile testing demonstrates fluorescence activation prior to macroscopic failure, whereas the neat SMP exhibits only minimal baseline fluorescence. These results demonstrate that mechanochemical sensing can be integrated into SMP networks through covalent mechanophore incorporation without compromising shape memory performance, providing a foundation for future structural health monitoring applications.