Highly Strong and Flexible Multiscale Nano Film Assembled by the CNC‐Nanohydrogel Ionic Liquids and Bacterial Cellulose for Optical Management Devices

ABSTRACT Biomass‐derived materials have garnered considerable interest due to their biocompatible performance and diverse sources. Optical management devices using biobased nanocellulose are essential in human‐machine interface interaction films, bionic skin, soft displays, and solar energy batteries. Herein, leveraging the synergistic effect of swelling and heterogeneous sulfation, the nanorod‐shaped hydrogel ionic liquids, the cellulose nanocrystals nanohydrogel ionic liquids (CNC‐nanogel‐IL), were efficiently prepared through a one‐step process using a novel reactive ionic liquid (RIL). The CNC‐nanogel‐IL nanorods could self‐assemble into free‐standing films with translucent appearances and layered nanostructures. Surprisingly, owing to the imidazole cations on the surface of nanorods, CNC‐nanogel‐IL films possessed outstanding flexibility and toughness based on multiple H‐bonds, which was nearly 6 times of conventional CNC films. The co‐assembly of the nanorod‐shaped hydrogel ionic liquid with bacterial cellulose can form multi‐nanoscale bio‐based films. The films demonstrated excellent transparency and haze performance, which was attributed to appropriate light scattering caused by the fine interspersion and integration of the 3D network‐structured BCNF and rod‐structured CNC‐nanogel‐IL. This innovative RIL method provided a new platform to prepare the nanorod‐shaped hydrogel ionic liquid. The multiscale nano‐layered structural films have shown potential applications in flexible displays, electronics, and wearable sensors.