Decoding Dual-Ion Synergy in AlCl3/ZnCl2 Hydrates: An Atomic "Interaction-Penetration-Dispersion" Mechanism for Ambient Cellulose Valorization.

Abstract

While the inorganic salt systems have demonstrated ambient cellulose dissolution, the atomic-scale mechanisms governing their unparalleled efficiency and sustainability remain unresolved. Here, we advance the typical inorganic salt solvent of the AlCl3/ZnCl2/H2O system by unraveling the hierarchical "interaction-penetration-dispersion" mechanism through multidimensional characterization and simulations. High-charge-density Al3+ ions initiate hydrogen bond disruption via strong electrostatic interactions (interaction), while their small hydrated radius enables ultrafast fibril infiltration (penetration). Concurrently, Zn2+ ions stabilize dissolved chains through solvation shielding (dispersion), achieving complete dissolution of cellulose within 10 min, 4-fold faster than single-ion ZnCl2 systems. Density functional theory confirms thermodynamic spontaneity (ΔG = -0.59 eV), and life cycle assessment demonstrates an 85% lower carbon footprint of 2.94 kg CO2-eq/kg of bioplastics compared to polyvinyl fluoride plastics. The regenerated cellulose films exhibit exceptional mechanical strength (94.9 MPa) and rapid biodegradability (100% degradation in soil within 20 days), addressing both performance and environmental demands. We establish universal design principles for green solvent engineering by correlating hydration-regulated ionic ratios with dissolution kinetics. This work bridges the gap between fundamental ion-cellulose dynamics and scalable production of multifunctional materials, including conductive hydrogels (41.72 mS/cm), ultralight aerogels (829.4 kPa), and flexible fibers, propelling sustainable applications in flexible electronics, eco-packaging, and eco-textiles.