Molecular engineering of interactions between 1,4-butanediol diglycidyl ether and cellulose in hydrated ionic solvents for sustainable packaging materials.

The development of robust and wet-stable cellulose-based plastics is pivotal for replacing conventional plastics in packaging. This study addresses the critical challenge of balancing cellulose dissolution and crosslinking within a Lewis acid solvent system (AlCl3/ZnCl2/H2O). We introduce 1,4-butanediol diglycidyl ether (BDDE) as a crosslinker and systematically investigate its multifaceted role. Our findings reveal that BDDE, beyond its crosslinking function, significantly alters the solvent microstructure by strengthening water-water hydrogen bonds and reducing free water activity and polarity, thereby inhibiting cellulose dissolution at contents >1 wt%. At the optimal 1 wt% BDDE, a homogeneous crosslinked solution is achieved, leading to regenerated films with exceptional mechanical properties: a dry tensile strength of 84.3 MPa and a wet strength of 27.5 MPa, retaining 32.6% of its dry strength after 24-h water immersion. The film also demonstrates a low water vapor transmission rate, excellent biocompatibility (cell viability >90%), and complete disintegration within 30 days, indicative of its high biodegradation potential. This work provides profound mechanistic insights into the dissolution-crosslinking trade-off, establishing a strategic paradigm for designing high-performance cellulose bioplastics.