Preparation, characterization, and applications of electrospun ultrafine fibrous PTFE porous membranes

Ultrafine fibrous poly(tetrafluoroethylene) (PTFE) porous membranes (UFPPMs) were prepared by sintering electrospun PTFE/poly(vinylalcohol) (PVA) composite membranes. Meanwhile, poly(acrylonitrile) (PAN) nanofibers were co-electrospun to reinforcing the material. The effects of changing the PTFE/PVA mass ratio, the sintering temperature and the heating rate on the structure and properties of the resulting membranes were investigated. To observe the structure evolution of the ultrafine fibers during the sintering process, the prepared UFPPMs were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and static water contact angles (WCA). A unique interconnected fibrous network structure was formed. The spinning and sintering conditions were optimized. Moreover, the UFPPMs exhibited a super-hydrophobicity and an excellent lipophilicity. They also performed well in harsh water (saline feed solution 3.5 wt% NaCl and 10 wt% NaOH) membrane distillation experiments. The permeate flux stabilized at 14.53 L m(-2) h(-1) and the salt rejection remained above 99.8% after operating for 35 h.