Multi-component polymeric membranes based on acrylamide monomers for fuel cells

The preparation, characterization, and evaluation of properties of proton exchange membranes (PEMs) for application in fuel cells (FCs) based on non-fluorinated hydrocarbons are described in this paper. A new class of membranes was synthesized by radical copolymerization, in aqueous medium, using low-cost monomers. The copolymers were constituted of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) as proton-conducting groups, hydroxyl ethylacrylamide (HEA) as crosslinking sites and styrene and N-isopropyl-acrylamide (NIPAM) as hydrophobic domains. The membranes were obtained by crosslinking the copolymers with glutaraldehyde in acidic medium under different conditions. The copolymers were characterized by infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (1H NMR), size exclusion chromatography (SEC) and thermogravimetric analysis (TGA). The membranes were also characterized by FTIR, which pointed out the changes resulting from the reaction with glutaraldehyde. TGA analyzes allowed to evaluate the thermal stability of the membranes in temperature ranges consistent with the use in FCs. The water uptake tests showed greater water absorption for samples without or with a low percentage of hydrophobic component. In addition, higher crosslinking agent content, acidification and higher curing temperatures led to a reduction in the degree of swelling. For the conductivity measurements, only the samples with NIPAM showed adequate stability to be submitted to the previous hydration treatment. As a result, these membranes presented higher conductivity values, close to those of commercial membranes. In general, membranes with more conductive groups in the composition, higher hydration and less crosslinks showed better conductivities. Finally, the set of samples with the best results was evaluated in oxidative degradation tests. In summary, the results presented allowed an evaluation of the adjustment of the properties of PEMs through the control of crosslinking and the formulation of the membranes. [Display omitted] •Novel non-fluorinated proton exchange membranes (PEMs) crosslinked by glutaraldehyde.•2-acrylamido-2-methyl-1-propanesulfonic (AMPS) acid monomers provided conductivity.•2-hydroxyethylacrylamide (HEA) content and cure conditions influenced crosslinking.•Styrene and N-isopropylacrylamide (NIPAM) monomers were used to reduce swelling.•The most conductive PEMs showed ionic conductivity close to Nafion in impedance tests.