High‐Strength, Fluorescent, Triboelectric Cellulose Hydrogel‐Derived Plastics Through Molecular Network Engineering for Energy Harvesting and Motion Sensing

Escalating electronic waste urgently requires the development of biodegradable smart electronic materials. Herein, a molecular network engineering‐based synergistic fabrication approach is pioneered to prepare cellulose‐based plastics (FCBPs) for triboelectric energy harvesting and sensing applications by integrating chemical cross‐linking, solvent exchange, and hot pressing. Using microcrystalline cellulose as the structural scaffold, a robust covalent network is built via epoxy cross‐linking, while dynamic hydrogen bonding and Eu ³⁺ coordination are simultaneously harnessed to achieve structural robustness and strong fluorescence properties in the FCBPs. The resultant plastics show a balance of superior properties, such as a tensile strength of 150.1 MPa, excellent solvent resistance, thermal stability up to 334 °C, promising hot‐processability, stable fluorescence with an intensity of 375 relative fluorescence units (RFU), complete biodegradability within 28 days, and favorable triboelectric performance. Notably, the FCBPs tailored for triboelectric nanogenerators (TENGs) deliver outstanding electrical performance with an open‐circuit voltage of 175 V, an operational durability exceeding 100 000 cycles, and a broad working temperature range (−20 to 100 °C). Using this tailored FCBP, a handwriting‐recognition sensor and a smart gait‐monitoring insole are further developed, enabling the precise and real‐time capture of handwriting traces and walking patterns. This work pioneers a molecular network engineering strategy for producing high‐performance, multifunctional cellulose‐based plastics, laying a solid foundation for eco‐friendly flexible electronics and sustainable human‐machine interaction platforms.