One-step ionic liquid-mediated dissolution-acetylation for high-performance regenerated cellulose ultrafiltration...

Cellulose-based ultrafiltration (UF) membranes often suffer from limited solubility and poor processability, which hinder the precise control of membrane morphology and performance. Herein, a single-step dissolution-acetylation protocol employing the ionic liquid [BMIM]Cl is introduced to fabricate regenerated cellulose (RC) ultrafiltration membranes with tunable degrees of substitution and optimized microstructure. By systematically varying the acetylation time and acetic anhydride concentration, a series of membranes with substitution degrees from 12.4% to 30.3% were obtained. The RC 20-36 h membrane (30.3% substitution) demonstrated a pure water flux of 293.81 L·m^-2·h^-1, bovine serum albumin (BSA) rejection of 83.44%, and flux recovery ratio of 89.59%. Surface hydrophilicity was enhanced (contact angle 17.79°), and tensile stress reached 1059 kPa owing to acetylation-induced disruption of intermolecular hydrogen bonding and increased chain rigidity. Uniform acetyl group distribution minimized structural defects and established a finely porous network that balances high permeability with selectivity and fouling resistance. This one-step approach integrates cellulose dissolution and functional modification in a single solvent, offering a sustainable and efficient route to high-performance UF membranes.