Polymer electrolyte membrane modification mechanism

Motorola Company developed a multiphase gel electrolyte by physical modification. One phase is a polar polymer such as PVDF or PAN, which can absorb solvent and offer channels for ion conduction. The other phase is a nonpolar polymer such as PP or PTFE (15-25 wt%), which absorbs little or no solvent, provides mechanical support, and reduces the volume change during the gelling process. It can also form a multilayer polymer electrolyte similar to that formed with the porous PP membrane (see Section 12.5). 

Nafion-based hybrid membranes are traditionally used electrolytes for both PEM fuel cell and DMFCs. " Besides Nafion, many composite engineering thermoplastic polymers based on poly(etheretherketone) (PEEK), polyvinyl alcohol (PVA), polysulfone, " polybenzimidazole (PBI), polyimide, and other organic-inorganic composite membranes have been employed as alternative membranes for both PEM fuel cells and DMFCs due to their lower cost, comparable conductivity, high mechanical and thermal stabilities, and easy modification as well. 

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