Carbon Black-Containing Cholesteric Liquid Crystal Elastomers Enabling Multi-Level Information Encryption and Multimode Actuation

Cholesteric liquid crystal elastomers (CLCEs) with a unique periodic helical arrangement of mesogens enable light-selective reflection, allowing variable coloration for applications in static information encryption and dynamic biomimetic actuation. However, most of the CLCEs are transparent and require a black contrast substrate to fully display the vivid structural color; moreover, achieving dynamic information encryption and stimulation-induced complex actuations simultaneously on the same CLCE material remains challenging. Here, CLCEs with clear and bright structural colors are prepared with the addition of carbon black (CB) nanoparticles. More importantly, multi-level encrypted information can be stored in CLCEs by using photomasks to adjust the exposure area and time, giving rise to encrypted patterns upon uniaxial extension or heating, and the CLCEs are also endowed with photothermal actuation capability attributing to the photothermal effect of CB. Under the stimulation of near-infrared (NIR) light or heat, the CLCE actuators can exhibit complex shape morphing and even multimode 3D actuation behaviors. This work provides a new solution for the design of advanced optical materials and devices, and may further expand the application of CLCEs in optical display and soft robotics.