Cellulose Membranes from Cellulose CO₂‑Based Reversible Ionic Liquid Solutions

Regenerated cellulose membranes (RCMs) were prepared from cellulose sufficiently dissolved in [TMGH]₂⁺[OOCOCH₂CH₂OCOO]^2–/DMSO (X_ILS = 0.2, X_ILs is the mole fraction of reversible ionic liquids in the mixed solvents) mixed solution under mild conditions (50 °C, 3 h, P_CO2 = 0.2 MPa) using different coagulation baths of ethanol, methanol, NaOH, and H₂SO₄ aqueous solutions. The structure and properties of these membranes were characterized using various characteristic technologies. The membrane regenerated from ethanol exhibited good thermostability and mechanical, water vapor, and oxygen barrier properties with a tensile strength of 56.2 MPa, a tensile strain of 20.4%, an excellent water vapor permeability of 8.7 × 10^–3 g μm/m² day kPa, and an oxygen permeability (OP) of 4.087 cm³ μm/m² day atm. The membranes regenerated from aqueous solutions of alkali and acid have an OP that tends to zero. This study provides a novel dissolving strategy to prepare cellulose membranes that have potential applications in the packaging, food, and agricultural industries.