Dynamic Fe ³⁺ ‐Cellulose Coordination Enables Ambient‐Temperature Fabrication of Water‐Resistant, Weldable, and Moldable Bioplastics

ABSTRACT

The inherent trade‐offs among processability, wet stability, and environmental footprint of biomass‐derived materials hinder the development of sustainable alternatives to petroleum‐based plastics. Here, we report an ambient‐solvent‐regulated strategy that transforms native cellulose paper into a robust, weldable, and rapidly biodegradable plastic using a ternary iron(III) chloride/zinc chloride/water (FeCl ₃ /ZnCl ₂ /H ₂ O) molten salt hydrate system. Leveraging the small ionic radius and high charge density of Fe ³⁺ , this system achieves rapid, ambient‐temperature partial dissolution of cellulose rather than full homogeneous disassembly, preserving the native microfiber skeleton while Fe ³⁺ ions serve as permanent yet dynamic molecular rivets within the regenerated matrix during in situ reconstruction. The resulting Fe ³⁺ ‐enhanced multiscale cellulose paper delivers 41.6 MPa dry tensile strength and 11.2 MPa wet strength. Dynamic Fe ³⁺ –O coordination bonds enable vitrimer‐like water‐assisted welding and binder‐free straw fabrication. Notably, the solvent remains effective over ten reuse cycles, with 75% strength retention. Life cycle assessment reveals a global warming potential of 1.82 kg CO ₂ ‐eq/kg, 40% and 21% lower than polylactic acid and polyethylene, respectively. Furthermore, the integrated Fe ³⁺ centers trigger Fenton‐like self‐destruction in soil, achieving complete degradation within 35 days. This work establishes a coordination mechanochemistry strategy for designing high‐performance bioplastics with closed‐loop life cycles.