Electrochimica Acta, Vol.175, 80-86, 2015
Characterisation of ion transport in sulfonate based ionomer systems containing lithium and quaternary ammonium cations
Two sulfonated ionomers based on poly(triethylmethyl ammonium 2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS) and containing mixtures of Li+ and quaternary ammonium cations are characterised. The first system contains Li+ and the methyltriethyl ammonium cation (N-1222) in a 1:9 molar ratio, and the Li-7 NMR line widths showed that the Li+ ions are mobile in this system below the glass transition temperature (105 degrees C) and are therefore decoupled from the polymer segmental motion. The conductivity in this system was measured as 10(-5) 5 cm(-1) at 130 degrees C. A second PAMPS system containing Li+ and the dimethylbutylmethoxyethyl ammonium cation (N-114(201)) in a 2: 8 molar ratio showed much lower conductivities despite a significantly lower T-g (60 degrees C), possibly due to associations between the Li+ and the ether group on the ammonium cation, or between the latter cations and the sulfonate groups. (C) 2015 Elsevier Ltd. All rights reserved.