Reinforcement of Highly Proton Conducting Multi‐Block Copolymers by Online Crosslinking

Abstract

Multi‐block copolymers with sulfonated polysulfones as hydrophilic blocks and polyethersulfones as hydrophobic blocks have been modified by two methods: covalent and ionic crosslinking. Both methods can easily be integrated into a membrane casting process and improve the membrane properties considerably: water uptake or swelling is decreased and the mechanical stability of the membranes is strongly increased, not only in terms of higher moduli but especially with respect to much higher fracture toughness. The phase‐separated morphology is not severely affected by crosslinking so that the advantageous properties of such membranes are retained. Covalent crosslinking is preferred since it does not sacrifice proton conductivity at all.

Nanometer‐Scale Water‐ and Proton‐Diffusion Heterogeneities across Water Channels in Polymer Electrolyte Membranes

“…However, reducing the number of sulfonic acid groups that retard the water diffusion can also decrease the water and proton uptake, by reducing the hydrophilic region and electro-osmotic drag, which in turn may affect the membrane stability, as well as decrease proton conductivity. [37] Crucially, this study reveals why the specific surface chemistry of Nafion membranes should be a key design element, besides channel structure, for optimizing water and proton transport. Furthermore, the experimental access to local and surface water diffusivity with site, domain and phase selectivity will serve as an important toolbox in the study of a large array of heterogeneous materials, where adsorption and transport to and out of active sites are critical to their function, with heterogeneous catalysts and fuel cell PEM being prominent materials of upmost significance.…”

H+-Conducting Aromatic Multiblock Copolymer and Blend Membranes and Their Application in PEM Electrolysis

“…As the second basic component of the acid-base blend membranes, the partially fluorinated polybenzimidazole F 6 -PBI was applied. The advantage of using a polybenzimidazole as a base in the acid-base blend is the resulting improved chemical and mechanical stability of the blend caused by the formation of ionic cross-link sites with the sulfonic acid groups of the sulfonated polymer [42]. The advantage of the PSU-Py is its extremely low basicity (the pK a of the protonated pyridine-N calculated by ACD is 2.7+/−0.1), which leads to very "loose" ionic cross-links.…”

Improving the Overall Characteristics of Proton Exchange Membranes via Nanophase Separation Technologies: A Progress Review

“…Titvinidze modified multiblock copolymers with sulfonated polysulfone as hydrophilic blocks and poly(ether sulfone) as hydrophobic blocks via either covalent or ionic crosslinking. The mechanical stability was strongly increased by the covalent crosslinking without severely sacrifice of nanophase separation and proton conductivity [73].…”