A research team led by Professor Li Bin from the Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, in collaboration with Professor Shen Jing from Northeast Forestry University and Assistant Professor Du Haishun from Michigan State University (USA), has proposed a “2‑second surface‑confined reconstruction” strategy adopting recyclable molten‑salt hydrate lithium bromide trihydrate (LiBr·3H₂O, LBTH). Without introducing polymeric additives, cross‑linkers or organic solvents, ordinary cellulose paper can be converted into cellulose‑based bioplastic with high strength, water resistance, thermal stability and full degradability only through ultra‑short‑duration solvent treatment followed by hot pressing.

The related work, entitled Two‑second surface‑confined reconstruction of cellulose paper via a recyclable molten salt hydrate for water‑resistant bioplastics, has been published in Green Chemistry, a journal of the Royal Society of Chemistry, and selected as the cover article.

The research reveals that treating cellulose paper in LBTH at 120 °C for merely two‑second enables controlled, partial dissolution only on the fibre surface, while the original micron‑scale fibrous skeleton inside the paper remains intact. During treatment, lithium and bromide ions jointly weaken intermolecular hydrogen bonds of cellulose, triggering surface fibrillation and chain rearrangement of fibres. After washing and hot‑pressing, in‑situ‑formed nanofibrils fill inter‑fibre voids and interpenetrate with micron‑sized fibres, constructing a dense nanofibril‑micron‑fibre interpenetrating network free of foreign polymer additives and chemical derivatization.

Structural characterizations confirm that the process relies mainly on physical reconstruction rather than chemical derivatization or crystal‑form transformation of cellulose; the material retains the native cellulose Iβ crystal phase. After optimized treatment, bulk density rises from 0.48 g·cm⁻³ to 0.71 g·cm⁻³ with greatly enhanced interfacial hydrogen‑bond interaction. Nanofibrils act as bridges and fillers between adjacent micron fibres, expanding fibre‑to‑fibre contact area and restraining fibre slippage as well as interfacial debonding under wet conditions, which simultaneously improves mechanical performance and water resistance.

For optimized samples, dry tensile strength reaches 69.9 MPa — 3.3 times that of untreated cellulose paper; wet tensile strength hits 27.1 MPa, representing an approximately 22.2‑fold improvement. The material maintains structural integrity under a 10 kg load even after one‑week water immersion, demonstrating outstanding wet‑state mechanical stability. Its 7‑day water‑absorption rate drops from 135 % for conventional paper to 82 %. Moreover, it stays structurally intact after 7‑day immersion in various organic solvents including ethanol, isopropanol, acetone, tetrahydrofuran and dimethylformamide.

This cellulose‑based bioplastic also delivers excellent thermal dimensional stability. Within 0‑120 °C, its coefficient of thermal expansion is −69.89 μm·m⁻¹·°C⁻¹, and the material retains its shape upon heating at 120 °C. Its maximum thermal‑degradation temperature reaches 348 °C, largely preserving the intrinsic thermal stability of cellulose.

Biodegradation tests show the material achieves complete degradation within roughly 20 days under simulated composting conditions and about 60 days under simulated landfill conditions, whereas polyethylene films of identical dimensions barely degrade under the same environment. The team further fabricated paper straws directly from wet reconstructed materials without extra adhesives. Conventional paper straws delaminate and soften within around 30 seconds in water. By contrast, reconstructed straws show no obvious delamination after 4‑hour water immersion and keep tubular geometry even after two‑day soaking.

This study offers a rapid, additive‑free, solvent‑efficient and scalable technical route for high‑performance modification of conventional cellulose paper. It holds promising application prospects for single‑use straws, food packaging and other short‑lived plastic‑replacement products, providing new insights for high‑value utilization of biomass materials and green manufacturing.