Abstract
      
      The present work describes the synthesis and characterization of a series of 
hybrid organo-inorganic ion exchange membranes for its use in fuel cells. Membranes 
were cast from dispersions of inorganic fillers in sulfonated polystyrene-block-
poly(ethylene-ran-butylene)-block-polystyrene solutions and Nafion solutions.  Silica 
gel, SBA-15 and sepiolite, all of them functionalized with phenylsulfonic acid groups, 
were used as fillers.
      
      Sepiolite and silica gel were functionalized by grafting of the phenyl ring to the 
solid. SBA-15 was prepared by sol-gel reaction. Functionalization was done by two 
methods. First one consisted in incorporation of phenyl at the synthesis wile the second 
one consisted on grafting of the phenyl ring to the prepared solid. Fillers were 
sulfonated under an SO3 atmosphere.
      
      SEBS was sulfonated using acetyl sulphate as sulfonation agent. After 
sulfonation, SEBS was dissolved in a THF/Ethanol mixture. To prepare Nafion 
membranes, a commercial 5% in low molecular weight alcohols solution was employed.
       
Fillers were characterized first by ionic exchange capacity and elementary analysis. By 
this way, appropriate fillers were chosen. Adsorption analysis and thermogravimetric 
analysis were done to the selected fillers. Particle size was obtained using SEM. 
      
      Membranes were characterized by water uptake, ion exchange capacity, SEM, 
TGA, DSC, DMA, FTIR and proton conductivity measurement using impedance 
spectroscopy. 
      
      From microstructural analysis was determined that sepiolite gives better 
reinforcement properties to the polymeric matrix. This behaviour is due to its lower 
particle size that allows better filler-matrix interaction. 
      
      The conductivity measurements showed that fillers incorporation doesn’t affect 
the conductivity compared to the pristine polymer. This is due to fillers sulfonation. 
Sulfonated SEBS has better conductivity than Nafion.
      
      In the last chapter, single cell test of the membranes is described. Run test were 
performed under O2/H2 atmosphere varying temperature and pressure.