Electrospun Naflon/PVDF Composite Membranes

摘要

In 2008, Pintauro and co-workers [1] showed how nanofiber electrospinning can be used to fabricate nanocomposite fuel cell membranes. The method and membrane morphology were alternatives to traditional membranes based on polymer blends and copolymers. These early membranes were fabricated by electrospinning an ionomer fiber mat followed by the impregnation of an uncharged, reinforcing polymer into the inter-fiber voids. The following post-electrospinning processing steps were required to convert an electrospun mat into a dense and defect-free fuel cell membrane: mat compression, fiber welding, ionomer annealing, and inert polymer impregnation. The resultant nanofiber composite membrane morphology decoupled the proton conduction function of the ionomeric nanofibers from the mechanical support and swelling control functions of the uncharged polymer. Dual-fiber electrospinning was introduced in 2011 as a means to eliminate a separate interfiber void-filling impregnation step during nanofiber composite membrane fabrication [2]. Now, the ionomer and the uncharged polymers are simultaneously electrospun as separate fibers that mix into a single mat. Subsequent processing, via hotpressing and either annealing or solvent vapor exposure, induces flow of one of the polymer components into the interfiber void space while retaining the nanofiber morphology of the second polymer.