Résumé
Fuel cell can be regarded as potential future alternative source of green Energy. PEMFC is composed of an electrolyte (usually a membrane which must be an ionic conductor) located between with anode and the cathode. The membrane is a functional polymer which bears protonic, cationic or anionic groups depending on the choice of use and must fulfill drastic requirements: high ionic conductivity and stability to HO° radicals, and to withstand their properties at 120 °C for about 5000 h. Fluorinated polymers that possess protogen groups are suitable candidates from various strategies: -either by "direct " radical copolymerization of fluoroolefins bearing protogen groups, -or by chemical modifications fluoropolymers. The present objectives of this plenary lecture were to find out new fluorinated membranes bearing either nitrogenous heterocycles such as (benz)imidazoles. or phosphonic acids (though less acidic than sulfonic ones but more dependant of the relative humidity4). The key strategy to enable a suitable compromise for both a high amount fluoromonomers and of functions that insure the conductivity is to carry out an alternating copolymerization of chlorotrifluoroethylene and a monomer which bears such a function. Hence, the radical copolymerization du CTFE with 2-chloroethyl vinyl ether (CEVE) to obtain poly(CTFE-alt-CEVE) copolymers was first achieved for further chemical modifications to synthesize original copolymers that containing (benz)imidazole or phosphonic acid. Fluoropolymers bearing imidazole functions require the obtaining of blend membranes involving sulfonated PEEK (which brings the protonic conductivity at low temperature) and led to conductivities values (ca. 10 mS.cm-1) but stable up to 150 °C.