Electrochemical energy conversion devices, based on polymer electrolytes have the potential for high system power densities, using relatively in-expensive components, at much higher efficiencies, than can be achieved with heat engines, at their relatively moderate temperature of operation.  Proton exchange membrane (PEM) based devices are mostly being considered for hydrogen applications due to their realized very high power densities.  Here the need is to develop PEMs that operate with less water and at elevated temperatures.  Anion exchange membrane (AEM) based devices have the potential for the use with multiple fuels as fuel cells, and to electrolyze not only water but also electrochemically reduce a range of substrates.  AEMs can be operated with a large variety of anions depending on the application.  Here the need is to use water efficiently for anion transport and as a reactant for hydrocarbons or for hydroxide conducting systems.  Next generation ionomers must be designed for water management and utilization and gas permeation or transport without compromising the mechanical properties of the material through excessive swelling or softening.  In this talk we will show multiple examples of how in-situ SAXS can be used to study the phase-separated morphology of state of the art ionomers. For most studies we use a simple environmental chamber where relative humidity and temperature can be controlled.   PEMs include hybrid polymers where the active group is an inorganic super acid, and hydrocarbon materials with novel backbones.  Water does not always simply swell the hydrophilic region, if the polymer is hydrophobic enough, the water can escape the fixed pores and swell the entire film.  AEMs will be presented with a range of polymer architectures and cations.  SAXS has been particularly useful here to help explain how water swells the large organic cations as well as how it facilitates ionic transport.

Using in situ SAXS to elucidate phase separated morphology and dynamics in next generation ionomers for polymer membrane based electrochemical energy conversion devices

248th National Meeting (2014)

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