Mixed conductive blends of SPEEK/PANI

Membranes were obtained by solvent evaporation from 70% sulfonated poly(ether ether ketone) and polyaniline in N-methyl-2-pyrrolidone [NMP] or N,N-dimethyl formamide [DMF]. SPEEK/PANI membranes were studied by UV-Vis spectroscopy, ion-exchange capacity, ionic and electronic conductivity and thermal properties, in order to observe the SPEEK doping effect and the solvent influence on the system. The protonation degree obtained, by elemental analysis and ion-exchange capacity, showed that almost 85 wt.% (in DMF) and 95 wt.% (in NMP) of SPEEK is required in order to obtain a 56% PANI protonation degree. The UV-Vis spectroscopy of the system in solution gave similar results. Electronic conductivity is in the order of 10^{- 6} S cm^{- 1} and the protonic conductivity values were high, in the order of magnitude useful for electrochemical devices, like fuel cells. All the SPEEK/PANI sample blends were stable up to 230°C and the char residue at 700°C is proportional to the component quantities. The temperatures up to which the blends were stable were up to 20°C higher than those for SPEEK.