Microporous CA/PVDF membranes based on electrospun nanofibers with controlled crosslinking induced by solvent vapor

In this study, a small amount of polyvinylidenefluoride (PVDF) was incorporated into cellulose acetate (CA) to electrospin CA/PVDF composite nanofiber membranes, followed by exposure to solvent vapor for crosslinking. Under controlled solvent vapor environment, the surfaces of the nanofibers were partially “melt,” and the contact points among the nanofibers formed physical crosslinks. It was demonstrated that the solvent vapor induced crosslinking was simple yet effective to enhance the mechanical strength of the resulting membranes. The degree of crosslinking could be controlled by adjusting the solvent vapor composition and the exposure time of the membrane in solvent vapor. To further reinforce the membrane, the CA/PVDF composite nanofiber membrane were electrospun onto a nonwoven substrate layer. The resulting membranes had pore sizes in the range of nm to µm. The membranes with a mean pore size of 0.75 µm and 0.59 µm exhibited a high pure water flux and good rejection to emulsion lattices when tested for emulsion separations. These results have revealed the potential of the membranes for separation and filtration applications.