Influence of chemical compositions on the properties of random and multiblock sulfonated poly(arylene ether sulfone)‐based proton‐exchange membranes

Abstract

The influence of chemical compositions on the properties of sulfonated poly(arylene ether sulfone)based proton-exchange membranes was studied. First, we synthesized three different series of random SPAES copolymers using three kinds of hydrophobic monomers, including 4,4 0 -dihydroxyldiphenylether, 2,6-dihydroxynaphthalene (DHN), and 4,4 0 -hexafluoroisopropylidenediphenol (6F-BPA) to investigate effects of hydrophobic components on the properties of SPAES membranes as proton-exchange membranes. Random SPAES copolymers with 6F-BPA showed the highest proton conductivity while random SPAES copolymers with DHN displayed the lowest methanol permeability among the three random copolymers. Subsequently, we synthesized multiblock SPAES using the DHN as a hydrophobic monomer and studied the effect of the length of hydrophilic segments in the multiblock SPAES copolymers on membrane performance. The results indicated that longer hydrophilic segments in the copolymers led to higher water uptake, proton conductivity, and proton/methanol selectivity of membranes even at low humidity. In addition, the morphology studies (AFM and SAXS measurements) of membranes suggested that multiblock copolymers with long hydrophilic segments resulted in developed phase separation in membranes, and ionic clusters formed more easily, thus improving the membrane performance. Therefore, both the kinds of hydrophobic monomers and the length of hydrophilic segments in SPAES copolymers would influence the membranes performance as proton-exchange membranes.

Fluorinated Poly(Arylene Ether)s

“…Research findings also showed that sulfonated PAEs containing -CF 3 moieties in the polymer backbone had higher proton conductivity compared with their non-fluorinated analogues [95]. Fluorinated PAEs have better phase-separated morphology and good proton conductivity.…”

Fully Aromatic Block Copolymers for Fuel Cell Membranes with Densely Sulfonated Nanophase Domains

“…[6] A great interest is currently focused on microphase separated block copolymers with highly sulfonated blocks to improve the proton conductivity at high temperatures and low relative humidity. [7][8][9][10][11][12][13] Two multiblock copoly(arylene ether sulfone)s with similar block lengths and ion exchange capacities (IECs) were prepared by a coupling reaction between a non-sulfonated precursor block and a highly sulfonated precursor block containing either fully disulfonated diarylsulfone or fully tetrasulfonated tetraaryldisulfone segments. The latter two precursor blocks were sulfonated via lithiation-sulfination reactions whereby the sulfonic acid groups were exclusively placed in ortho positions to the many sulfone bridges, giving these blocks IECs of 4. , prepared by using SDCDPS and hydroquinone.…”

Fabrication and characterization of electrospun sulfonated poly(phthalazinone ether ketone) mats as potential matrix of reinforced proton exchange membranes

“…To solve these problems, efforts have been made to develop alternative PEMs. One solution is to develop novel alternative PEMs based on the sulfonated aromatic hydrocarbon polymers, such as sulfonated poly(arylene ether sulfone)s, sulfonated poly(arylene ether ketone)s, sulfonated polyimides, and sulfonated organic–inorganic hybrids . The other is to modify Nafion membrane, including the reinforcement of Nafion membrane with a supporting porous substrate, the incorporation of inorganic fillers and the forming of methanol‐blocking layer …”