Scale-up fabrication of PVDF-HFP nanofibrous membrane with unique surface properties for efficient separation of oil from water

Herein, the unique wrinkled surface of polyvinylidene fluoride-hexafluoropropylene nanofibrous membrane was well developed by a one-step fabrication method just by adjusting the ratio of binary solvent and humidity. The well-tailored process was proposed complying with the evolutionary mechanism that a different volatilization temperature of binary solvent provides buffer time for the formation of a polymer/solvent-rich phase, subsequently water vapor solidifies the polymer jet, forming the unique surface on the resultant nanofiber. The intrinsic wrinkled surface structure enhances the roughness and endows the membrane with robust superhydrophobic characteristics. Meanwhile, the excellent mechanical property (stress at break 6.79 MPa, strain at break 136.8%) widens its applicability in industrial employment. Furthermore, the synthesized membrane exhibits stable results in oil–water separation in terms of good separation efficiency (>99.6%) and flux (>1100 l/m2h). This is a general approach for the synthesis of many other materials at lower cost and holds a great potential to be employed in practical engineering applications beyond the oil–water separation.