Synthesis and Membrane Properties of Sulfonated Poly(arylene ether sulfone) Statistical Copolymers for Electrolysis of Water: Influence of Meta- and Para-Substituted Comonomers

Abstract

Two series of high molecular weight disulfonated poly(arylene ether sulfone) random copolymers were synthesized as proton exchange membranes for high-temperature water electrolyzers. These copolymers differ based on the position of the ether bonds on the aromatic rings. One series is comprised of fully para-substituted hydroquinone comonomer, and the other series incorporated 25 mol % of a meta-substituted comonomer resorcinol and 75 mol % hydroquinone. The influence of the substitution position on water uptake and electrochemical properties of the membranes were investigated and compared to that of the state-of-the-art membrane Nafion. The mechanical properties of the membranes were measured for the first time in fully hydrated conditions at ambient and elevated temperatures. Submerged in water, these hydrocarbon-based copolymers had moduli an order of magnitude higher than Nafion. Selected copolymers of each series showed dramatically increased proton conductivities at elevated temperature in fully hydrated conditions, while their H gas permeabilities were well controlled over a wide range of temperatures. These improved properties were attributed to the high glass transition temperatures of the disulfonated poly(arylene ether sulfone)s.

Essentials of High Performance Water Electrolyzers – From Catalyst Layer Materials to Electrode Engineering

“…Additionally, there are widespread works on novel membrane materials other than Nafion, for example, novel ionic conducting polymers such as sulfonated poly(arylene ether sulfone) or sulfonated poly(phenylene sulfone) with high ionic conductivity and low gas permeability have been developed and deployed for PEMWE. [151,152] This membrane class showed high conductivity and low gas crossover. However, the mechanical and chemical long term stability still needs to be improved.…”

Structures and properties of polymers in ion exchange membranes for hydrogen generation by water electrolysis

“…The effect of meta and para dispositions of ether linkage on aromatic rings in disulphonated PAES was studied by Daryaei et al, 84 by synthesizing two high molecular weight series of copolymers (Figure 10). The incorporation of meta (25 mol%) substituted monomer within para (75 mol%) substituted monomer led to reduction in chain stiffness as well as enhancement in water absorption and proton Use of poly(ether sulphone) (PES) was done in a blended combination with sulphonated poly(ether ether ketone) (SPEEK) for the preparation of PEMs for WE.…”

“…Synthesis of two high molecular weight random copolymers: a 100% para‐substituted phenolic hydroquinone‐based copolymer or a 75% para‐substituted and 25% meta‐substituted phenolic hydroquinone‐resorcinol copolymer. Redrawn and reproduced from Reference 84 …”

Effect of steric constraints on the physico‐electrochemical properties of sulfonated polyaromatic copolymers

“…There also exist growing concerns over the environmental implications regarding the synthesis, implementation and long-term degradation of perfluorinated chemicals. [14][15][16][17][18] These drawbacks have motivated significant research efforts directed towards alternative, fluorine-free PEM materials.…”

“…Despite its popularity, attributed to excellent durability and respectable electrochemical performance, 12,13 PFSA suffers from notable drawbacks including a high material cost and high reactant gas crossover. There also exist growing concerns over the environmental implications regarding the synthesis, implementation and long‐term degradation of perfluorinated chemicals 14–18 . These drawbacks have motivated significant research efforts directed towards alternative, fluorine‐free PEM materials.…”