Switchable Chiroptical Flexible Films Based on Chiral Helical Superstructure: Handedness Inversion and Dissymmetric Adjustability by Stretching

Intelligent and controllable circularly polarized absorption and emission switching with high dissymmetric factors have attracted great attention due to the significant potential applications in chiral chemistry, chiral photonics, and electronics. However, the lack of examples to achieve freely switchable and adjustable chiroptical properties within a single material, especially in the deformable solid materials, limits the further continuous progress. Herein, an unprecedented, simple, and scalable way to achieve the above goal is presented. A stretchable spin-coated thin film is fabricated from chiral helical substituted polyacetylene and thermoplastic polyurethane. Macromolecular chains self-organize into hierarchically chiral superstructures under stretching, facilitating the film to absorb/emit circularly polarized light with opposite handedness from the two faces of the film. The dissymmetry intensity can be adjusted flexibly by controlling the elongation and recovery of the film. The nonreciprocity and chirality adjustability behaviors in stretchable solid materials represent a fundamental advancement and provide new opportunities for the design, preparation, and applications of chiroptical materials.