In this work we report the synthesis and physical properties (thermal stability, diffraction patterns, and conductivity measurements) of a methacrylate-type polymer with zwitterionic pendant groups. The parent polymer, poly(sulfobutylbetaine of 12-ethyl-3,6,9-trioxa-12-azatetradec-1-yl 2-methylacrylate) (herein labeled PMBS-4) is used to prepare polymer/lithium salt complexes (PMBS-4/LiCl, PMBS-4/Li-triflate, and PMBS-4/LiClO 4 ). The resulting electrolyte polymers show mechanical properties akin to elastic solids. The glass transition temperature is close to 20 °C for all specimens, and PMBS-4/LiCl is thermally stable up to 187 °C. The conductivity of these materials varies with temperature, following an Arrhenius-like relationship. The conductivity of the solid polymer electrolytes, SPE, follows the order PMBS-4/LiClO 4 > PMBS-4/LiCl > PMBS-4/Li-triflate. The ionic conductivity of these materials is clearly affected by the anion of Li salt.

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This work summarizes the results obtained from the modification of perfluorinated sulfocationic MF-4SC membranes by in situ polymerization of aniline. The transport properties of polyaniline/MF-4SC composite membranes after different times of polymerization have been analyzed. It is observed that after 3 h of aniline polymerization, composite membranes exhibit higher protonic conductivity compared to the pristine sample. The performance of fuel cells containing membrane electrode assemblies (MEAs) from MF-4SC and polyaniline/MF-4SC has also been studied. The kinetic parameters governing the voltage dependence on current density have been estimated and the results have been fitted to a previously established one-dimensional isothermal model by Springer et al. [ J. Electrochem. Soc. 138 , 2334 (1991)] . Good agreement between experimental data and model has been found for low density currents. Some insights about the membrane proton conductivity mechanism are given.