One pot approach for a recyclable, high-strength, wet-stable cellulose film

Cellulose has gained significant attention for its abundant sources, degradability, and biocompatibility in achieving the sustainable development goals. However, the mechanical and waterproof qualities of cellulose-based polymers are typically suboptimal, thereby constraining their potential for high-value applications. Moreover, the problematic recovery of cellulose solvents is challenging for resources and the environment. The aluminum chloride/ zinc chloride/ water (AlCl3/ZnCl2/H2O) system was utilized as the cellulose dissolving solvent and the chemical crosslinking catalyst in this investigation, enabling the production of high-performance cellulose films through a "one-pot" approach. By opening the ring in an acidic solution with epichlorohydrin (EPI), 1, 4-butanediol diglycidyl ether (BDDE), or polyethylene glycol diglycidyl ether (PEGDGE), efficient chemical crosslinking was achieved, reducing the number of reagents and optimizing the film performance in all aspects. The film tensile stress reached 197.37 MPa and elongation at break reached 33.13 %. Furthermore, after soaking in water for 180 days, the films exhibited good water stability without any evident swelling behavior. After being buried in the soil for 20 days, such films could be totally degraded. Moreover, the films could redissolve in the AlCl3/ZnCl2/H2O system without weakening mechanical properties. This safe cellulose film was a more environmentally friendly alternative to plastic packaging film. Furthermore, the AlCl3/ZnCl2/H2O system exhibited high recyclability, with salt recovery reaching 83% of the initial fresh solvent after five cycles. The excellent efficiency of the crosslinking approach and the overall greenness of the process present a novel notion for further research.