A robust and environmental-friendly strategy for preparation of PTFE membranes with high separation accuracy and sequential separation performance

Polytetrafluoroethylene (PTFE) is considered robust membrane material in membrane processes especially under harsh environment. It is vital to realize the regulation and control of the pore size during manufacture process of PTFE membrane, because it directly affects the separation accuracy and permeability. Herein, we feasibly enhanced the controllability of the pore structures by tailoring the electrospinning/electrospraying process and calendaring conditions to design PTFE membranes with high separation accuracy. This strategy avoided the use of organic solvents or lubricants during preparation process, thus showing environmental-friendly advantages. The results showed that the membrane pore structure could be evolved from interwoven fiber network to three-dimensional bicontinuous structure by increasing the amount of PTFE in spinning solution. Moreover, the pore size could be controlled by improving the fusion degree of PTFE nanostructures via adjusting calendaring pressure. Meanwhile, the PTFE membranes presented selective sequential separation property of silica nanoparticles with diameters from 12 nm to 1000 nm. The PTFE membranes manufactured with controllable pore size and structure by this strategy could provide a promising alternative for energy-efficient and high-accurate particle screening, solution recovery, and grading separation.