Résumé
Fluorinated functional polymers (1) exhibit remarkable properties (thermal and oxidative stabilities, chemical inertness, low refractive index, good surface properties, etc) that enable them to find numerous applications in high tech fields: aerospace, energy, automotive industries, optics, microelectronics, and engineering. Fluoropolymers for energy are nowadays seeing an enormous growth in both their number and variety. Although most membranes for fuel cells are made from perfluorosulfonic acid polymers such as Nafionâ, Flemionâ, Hyflonâ, Fumionâ, 3MâMembranes, or Aciplexâ, produced from the radical copolymerization of tetrafluoroethylene with aliphatic perfluorinated vinyl ethers, few have been achieved from aromatic functional fluoropolymers. The objective of this presentation deals with the syntheses of new generations of original membranes prepared from aromatic and aliphatic fluorinated copolymers incorporating fluoromonomers such as vinylidene fluoride (VDF, F2C=CH2), hexafluoropropene (HFP, F2C=CFCF3), and an aromatic fluorinated monomer functionalized by a sulfonic acid, or -trifluoromethacrylic acid (MAF). However, membranes from perfluorosulfonic acids suffer from high cost, methanol crossover and they usually show a high drying when the membrane is used at temperatures higher than 80 °C, hence undergoing severe damages. It is urgent to find out other systems which do not require any water and imidazole ring can play a suitable role thanks to potential jumps of proton from donor to acceptor nitrogenated sites. A further strategy deals with the synthesis of original alternated poly(CTFE-alt-VE) copolymers2 (where CTFE and VE stand for chlorotrifluoroethylene and vinyl ether, respectively). After reporting the synthesis of the monomer (A) and the copolymer (B), the molecular weights and the thermal properties (Tg and Tdec) of which are listed, various membranes prepared by casting will be characterized. First, the thermal properties followed by the electrochemical properties: the conductivity values reached up to 14 mS.cm-1 according to the temperature and the relative humidity. 1. B. Améduri B. Boutevin, Well Architectured Fluoropolymers: Synthesis, Properties and Applications, Elsevier, Amsterdam, 2004 2. L. Delon, B. Améduri, B. Boutevin, D. Jones, J. Rozière, G. Frutsaert, X. Glipa World Patent WO2007/141441 2007-12-13 (assigned to Peugeot Citroën/CNRS).