Step‐wise non‐solvent induced phase separation of polyacrylonitrile/thermoplastic polyurethane self‐supportive filtration membranes

Abstract This study investigated the fabrication of polyacrylonitrile (PAN) membranes using non‐solvent induced phase separation methods, with the addition of thermoplastic polyurethane (TPU) as an additive. The incorporation of TPU and the utilization of stepwise induced phase separation techniques resulted in notable improvements in membrane structure and water filtration performance. Scanning electron microscopy revealed that membranes with TPU exhibited a denser pore network and finer primary channels, leading to enhanced water flux and protein rejection rates. Mechanical testing indicated that TPU addition improved the membrane's mechanical properties, particularly its elongation at break and tensile strength, especially under wet conditions. Additionally, optimization of the coagulation bath involved methanol spraying followed by water immersion, resulting in membranes with further enhanced flux and rejection properties. Compared with neat PAN membranes, the membranes with TPU exhibited increased water flux from 405 to 539 L/m 2 h, as well as improved elongation at break and tensile strength in both dry and wet conditions. Furthermore, the combination of stepwise induced phase separation significantly enhanced the water flux from 342.7 to 483.0 L/m 2 h, while also improving the retention rate of ovalbumin from 25.7% to 31.5%.