Abstract: Nanofiber electrospinning has numerous advantages in the fabrication of composite materials. The process, which allows for the formation of polymer nanofibers with submicron diameters, is highly tunable and can accommodate various polymer chemistries and nanoparticle additives. A dual-fiber electrospun mat, which consists of dissimilar fibers that are simultaneously electrospun onto a common target, allows for a forced assembly of materials that may be otherwise immiscible. Thus, the resultant structure can have a combination of advantageous properties for various applications due to the controlled ratio and chemistry of the fibers.
The advantages of dual fiber electrospinning can be used in the fabrication of membranes for H2/air fuel cells and water electrolysis, which often require conflicting properties to achieve high performance. Proton-exchange membranes, for example, should be highly conductive (which is associated with degrees of hydrophilicity) while maintaining low-dimensional changes upon hydration. Alternatively, bipolar membranes require a high interfacial area to achieve a low trans-membrane voltage drop, especially at high current densities.
In this talk, I will describe the dual-fiber electrospinning process and how the continuous network and interpenetration of the two components are beneficial for membrane applications. First, the structure of a composite proton-exchange membrane is varied through the electrospinning process, leading to a multilayer membrane structure. Second, the conductivity of a composite membrane is increased by incorporation of a highly charged sulfonated silica network. Finally, bipolar membranes with a 3-D junction are fabricated to reduce their trans-membrane voltage drop.