Programmable chiroptical multilayer films assembled from self-healing stretchable elastomers for information encryption

Abstract

Flexible chiroptical materials with strong and tunable optical activity are highly desirable for applications in optical encryption, quantum communication, and wearable photonic devices. Recently, various strategies have been developed for constructing flexible chiral plasmonic films. Among these, combining uniaxial alignment with twisted multilayer stacking offers an effective and scalable route to generate strong chiroptical signals using achiral building blocks. However, a key challenge remains in achieving highly ordered plasmonic nanostructures within deformable polymer matrices, which is essential for constructing tunable and robust chiral optical systems. Herein, we report a self-healing, ultra-stretchable hybrid elastomer composed of silver nanowires (AgNWs), waterborne polyurethane (WPU), and tempo-oxidized cellulose nanofibers (TOCNF), which enables the efficient formation of aligned anisotropic structures via uniaxial wet-stretching. The resulting AgNWs@WPU/TOCNF films exhibit ultrahigh stretchability (>1000%) and retain their orientation after drying. Importantly, the intrinsic self-healing capability enables seamless twist-stacking of pre-aligned films through water-assisted interfacial fusion, resulting in robust multilayer architectures with strong circular dichroism signals, characterized by a maximum ellipticity of 13.3° and an absorption dissymmetry factor exceeding 0.6. Further integration with a fluorescent layer yields circularly polarized emission films with a luminescence dissymmetry factor up to 0.5. Leveraging the programmable optical responses, a multilayer encryption device was fabricated for information encoding and decoding based on polarization states. This work provides a scalable and modular platform for developing self-healing chiroptical devices with tunable optical functionalities and high potential for photonic encryption and smart wearable technologies.