A green "Sandwich" multilayer membrane for food preservation: Introducing a dense Interface between PBAT and paper for enhanced gas-barrier performance.

To overcome the poor gas barrier of PBAT in biodegradable food packaging, a green "sandwich" multilayer membrane (SMM) was fabricated by a conventional paper-coating and lamination process. The membrane consisted of a PBAT water-resistant layer, a ternary interfacial coating of cellulose microgels, cellulose nanofibers, and nanoclay, and a paper support layer. The optimized SMM121 (1:2:1) achieved an oxygen permeability of 0.6 cm3·cm/(cm2·d·0.1 MPa), a CO₂/O₂ selectivity of 10.3, and a water vapor permeability of 13.5 g·mm/m2·d, compared with 43.4 g·mm/m2·d for the corresponding ternary colloid membrane. Strong interfacial adhesion was obtained, with lap-shear strengths of 16.2 MPa on paper and 2.4 MPa on PBAT. In preservation tests, after 28 d, macadamia nuts packaged with SMM121 showed an acid value of 0.28 mg/g, lower than PBAT and PE controls. SMM121 also better preserved apple juice quality during 21 d of storage.