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

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.