Eco-friendly fabrication of bacterial cellulose nanopaper with enhanced strength and toughness from a powder suspension.

The growing demand for sustainable alternatives to petroleum-derived materials in packaging, electronics, and filtration highlights the need for robust and eco-friendly fabrication methods for cellulose-based films. However, cellulose nanopapers with improved mechanical performance are commonly produced using chemical modification or energy-intensive processing, which may limit their scalability and environmental sustainability. In this study, bacterial cellulose (BC) nanopapers with enhanced strength and toughness were fabricated from a non-oxidized BC powder suspension using ultrasonication followed by boiling-water (BW) treatment. BC powder was prepared from wet BC pellicles hydrated in distilled water, sonicated, boiled at 100 °C for 2, 4, and 5 h, and oven-dried. Nanopapers were then fabricated by resuspending the treated BC powder in water followed by casting. The results showed that BW treatment simultaneously improved tensile strength and toughness. The 5-h boiling treatment results in increased tensile strength, tensile modulus, elongation at break, and toughness by 89% (81.9 MPa), 261% (1,383.5 MPa), 26% (14.8%), and 148% (6.7 MJ/m3), respectively, compared with the non-boiled nanopaper. The BW-treated nanopaper also exhibited a broader plastic deformation region and fewer pores. These findings demonstrate that boiling-water treatment of an ultrasonicated, non-oxidized BC powder suspension provides a simple, chemical-free, and pressure-free route for producing BC nanopapers with enhanced mechanical performance.