Cholesteric liquid crystal elastomers (CLCEs) exhibit strain-induced structural color changes arising from deformation-driven modulation of their helical pitch, making them attractive mechanochromic optical materials for soft sensing and deformable photonics. However, the practical implementation of free-standing CLCE films is severely constrained by their poor mechanical robustness. Typical CLCEs possess ultralow elastic moduli in the kilopascal range and are fabricated as ultrathin films, rendering them highly susceptible to tearing and difficult to handle or integrate into functional systems. Moreover, chemistry-based attempts to enhance mechanical strength inherently involve a trade-off between robustness and stretchability, limiting the extent to which optical performance can be improved through molecular design alone. To address these intrinsic limitations, recent studies have adopted substrate-assisted fabrication and deformation strategies in which CLCE films are coupled with mechanically supportive substrates. This approach decouples optical functionality from mechanical load-bearing requirements, allowing CLCEs to maintain high mechanochromic sensitivity while gaining structural stability and design flexibility. In this Perspective, we highlight how substrate-assisted CLCE architectures expand mechanochromic behavior beyond the constraints of free-standing films, enabling broadband photonic band modulation, spatially resolved and directional optical responses, system-level optical sensing, and plasticity-mediated irreversible mechanochromic imprinting. Collectively, these advances establish substrate assistance as a unifying design-applicated framework for robust mechanochromic optical systems.
Lee et al. (Thu,) studied this question.