Eco-Friendly PLA/PBAT Janus Nanofibers Featuring Tensile-Induced Flux Enhancement for Selective Oil–Water Separation

Membrane-based oil–water separation has attracted extensive attention as an efficient and energy-saving strategy for oily wastewater treatment; however, most conventional separation membranes are fabricated from petroleum-based polymers, which are difficult to degrade after disposal and may cause secondary environmental pollution. Therefore, developing high-performance oil–water separation membranes with environmental sustainability remains a critical challenge. In this work, a biodegradable PLA/PBAT Janus nanofibrous membrane is fabricated via dual-channel side-by-side electrospinning using polylactic acid (PLA) and poly(butylene adipate- co -terephthalate) (PBAT) as the polymer matrix. Hydrophilic and underwater oleophobic modification of the membrane is achieved through a mild interfacial microswelling process, which introduces hydrophilic functional groups and enhances surface roughness. As a result, the modified membrane exhibits significantly improved wettability, with the water contact angle reduced to approximately 20° and the underwater–oil contact angle exceeding 130°. Benefiting from the aligned nanofiber arrangement, interconnected porous structure, and the stretchability of PBAT, the hydrophilic PLA/PBAT Janus membrane demonstrates excellent separation performance toward oil-in-water emulsions under gravity-driven conditions, achieving a high permeation flux of up to 2985 L·m –2 ·h –1 under tensile deformation and maintaining a stable flux of approximately 1000 L·m –2 ·h –1 after 120 separation cycles, while oil rejection efficiencies remain around 98% for different oil phases. This study demonstrates that biodegradable Janus nanofibrous membranes based on PLA and PBAT can simultaneously achieve high separation efficiency, mechanical robustness, and environmental sustainability, providing a promising green membrane material for efficient oil–water separation applications.