Exploring green solvents for the sustainable fabrication of bio-based polylactic acid membranes using nonsolvent-induced phase separation

Green and sustainable membrane technology has recently gained attention from the membrane community to minimize the negative environmental impacts associated with conventional membrane production in industries, which rely on petrochemical engineering plastics and toxic organic solvents. While the fabrication of biobased and biodegradable polymeric membranes using common organic solvents has been reported, eco-friendly membrane-fabrication techniques using greener solvents are required to improve sustainability and reduce the negative environmental impact of the membrane industry. For the first time, this study comprehensively investigates the potential use of green solvents for preparing polylactic acid (PLA) membranes via the phase separation technique. PLA solubility and phase separation experiments, employing various green solvents were conducted to examine the potential applicability of these solvents for membrane fabrication. Porous PLA membranes exhibit different surface and pore structures depending on the thermodynamic and kinetic parameters of the green solvents. Based on the phase separation study, both fine PLA ultrafiltration membranes with controllable molecular weight cut-off and mechanically robust PLA microfiltration membranes with bi-continuous pore structure were successfully prepared using methyl lactate. The prepared green membranes showed a competitive filtration performance implying that the fully bio-based PLA membranes could substitute the conventional engineering plastic-based membranes in versatile membrane filtration and separation processes, especially single-use or consumable membrane products in environmental and healthcare industries.