Highly Phase Separated Aromatic Ionomers Bearing Perfluorosulfonic Acids by Bottom-up Synthesis: Effect of Cation on Membrane Morphology and Functional Properties

Abstract

Proton-conducting aromatic-based ionomers bearing superacid side chains are usually synthesized by polymer postmodification, which does not allow controlling ion exchange capacity and ionic group distribution along the ionomer and, thus, its chemical structure and functional properties. Bottom-up approach overcomes this problem. Here, we report the preparation of a novel ionic monomer and its polycondensation with commercial monomers. The obtained random ionomers are the first to show high phase separated organization at macro-, micro-, and nanoscale, common to the reference protonconducting material Nafion. Additionally, membranes were cast from the solutions of ionomers in their Li + and K + forms in order to study the cation's influence on both morphology and performance of the materials. The difference in ionic domain organization, depending on the initial cationic form of the ionomers, was reported for the first time. The proposed materials show superior proton conductivity than Nafion, especially at low relative humidity, which makes them potential substitute of the benchmarked Nafion for fuel cell application.

Novel single-ion conducting electrolytes based on vinylidene fluoride copolymer for lithium metal batteries

“…The VEPFSIS introduces two anions, i.e., sulfonimide and sulfonate anions (VEPFSIS-Li), the last one being obtained by the hydrolysis of fluorosulfonic function in presence of LiOH [51,52]. In a typical synthesis, Li-PVDF was prepared in a 100 mL Hastelloy Parr autoclave equipped with a bourdon pressure gauge, a rupture disk and inlet and outlet valves.…”

Perfluorosulfonyl Imide versus Perfluorosulfonic Acid Ionomers in Proton‐Exchange Membrane Fuel Cells at Low Relative Humidity

“…Recently, increasing the acidity of the functional moiety has emerged as a plausible approach to favor proton transport, and significantly higher proton conductivities were reported as compared to those of directly sulfonated aromatic ionomers . The enhanced conductivity was attributed to (i) the higher acidity of the acidic side chains (p K a ≈−6 in perfluorosulfonic acid and p K a ≈−1 in aryl sulfonic acid) inducing higher ability to dissociate proton at low relative humidity (RH); and (ii) the presence of a flexible hydrophobic spacer between the backbone and the acidic function, favoring nano‐phase separated microstructures with well interconnected ionic clusters .…”

“…[7][8][9][10] Recently,i ncreasing the acidity of the functional moiety has emerged as ap lausible approach to favor proton transport, and significantly higher proton conductivities were reported as compared to those of directly sulfonated aromatic ionomers. [11][12][13][14][15][16] The enhanced conductivity was attributed to (i)the highera cidity of the acidic side chains (pK a %À6i np erfluorosulfonica cid and pK a %À1i na ryl sulfonica cid) [17] inducing higher ability to dissociate protona tl ow relative humidity (RH);a nd (ii)the presence of af lexible hydrophobic spacer between the backbonea nd the acidic function, favoring nanophase separated microstructures with well interconnected ionic clusters. [18,19] As ac onsequence, aromatici onomers obtained by combining multiblock structure with perfluorosulfonic acid sidechains with optimized chemical structurea nd membrane manufacturing condition showedi mproved fuel cell performance andd urability as compared to those of Nafion.…”

Synthesis of novel sulfonated poly(arylene ether)s containing a tetra-trifluoromethyl side chain and multi-phenyl for proton exchange membrane fuel cell application

“…Moreover, the worst disadvantage is high material costs due to expensive uorination and complex manufacturing processes. [5][6][7][8] In recent years, sulfonated hydrocarbon polymers have attracted signicant attention as alternative polymer electrolyte membranes to Naon. These sulfonated polymers, such as sulfonated poly (arylene ethers), sulfonated poly(arylene ether ketone)s, sulfonated polyimides, and sulfonated polybenzimidazoles, 9,10 have been extensively investigated owing to the easy adjustment of their molecule structure, high thermal stability, good chemical stabilities, appropriate mechanical properties, processability, and low production cost.…”

“…The presence of uorine substitution is expected to lead to good chemical stability and better hydrophilic/hydrophobic phase separation. 8,20,21 Furthermore, the uorine substituted group is a strongly electron-withdrawing group, which can deactivate the aromatic ring to prevent the attack of the sulfonating agent. 22,23 Herein, we report the synthesis of novel poly(arylene ether)s composed of triuoromethyl side chains on multi-phenylated bisuoro monomer with uorene-based and multi-phenylated bisphenol monomers.…”