Co-generation of cellulose framework and zinc ferrite: An innovative method for preparing a high-transparency, low-haze, highly efficient UV and high-energy blue-light dual-blocking flexible film.

This research employed a novel approach and ingenious experimental design, enabling the chlorides serving as the zinc source and iron source of zinc ferrite (ZnFe2O4) to dissolve together with cellulose in the ionic liquid. The precursor solution was placed in an alkaline regeneration-synthesis bath, the in-situ synthesis of ZnFe2O4 nanocrystals was achieved while the cellulose framework was regenerated. This method fully utilized the electrostatic adsorption effect of cellulose with metal ions and its ability to serve as a good framework. As a result, a cellulose-based composite film with high transparency (87.2%), low haze (2.87%), strong mechanical properties (48.8 MPa tensile strengthen and 9.1% elongation at break), ultraviolet full shielding and blue light adjustable shielding (71.87%-100%) was successfully prepared, and the prepared ZnFe2O4/cellulose composite film possessed the self-extinguishing property and motion monitoring capability. This method achieved the co-generation of ZnFe2O4 and regenerated cellulose framework as the "soul" and "meat" of this bio-based functional composite film - the light shield and the mechanical framework. It endowed the former with mechanical properties and a firmly anchored substrate, and endowed the latter with attractive light management functions, providing a new possibility for the high value utilization of bio-based materials. The obtained cellulose composite film also possesses the self-extinguishing property and can be utilized as a stable motion monitoring device.