A novel sPEEK nanocomposite membrane with well-controlled sPOSS aggregation in tunable nanochannels for fast proton conduction

Abstract

To greatly increase the proton conductivity of a sPEEK nanocomposite membrane without water swelling problems, sulfonated PEEK (sPEEK) nanocomposite membranes were prepared by regulating the nanocomposite concentration of sulfonated POSS (sPOSS). Incorporation of sPOSS into sPEEK afforded a 39% increase in proton conductivity at 80 °C/100% RH and a 70% increase in cell performance at 1.5 wt% sPOSS concentration. In particular, water swelling problems were not observed even with the attained proton conductivity, as with Nafion. The water swelling of the pristine sPEEK membrane was 18.8%; it increased to 24.4% at 5.0 wt% of sPOSS loading, which was 11.1% lower than that of Nafion. The high modulus of sPOSS and the good distribution of sPOSS also enhanced the tensile strength by 40.5% and the strain by 65.8% compared with the pristine sPEEK membrane. At more than 1.5 wt% sPOSS concentration, the conductivity and power output of the nanocomposite membranes decreased despite the increased IEC, which is highly related to aggregation of sPOSS nanoparticles in the proton conducting nanochannels and changes in the nanochannel size. The sizes of the nanochannels were measured by SAXS, and it was found that expansion of the nanochannels was enhanced at 1.5 wt% by the best distribution of sPOSS and absorption of water. The increased IEC, expanded nanochannels and distribution of sPOSS without aggregation promoted proton conduction through the nanochannels.

Versatility of sulfonated poly (vinylidene fluoride‐co‐hexafluoropropylene) membranes incorporated with sulfonated octaphenyl polyhedral oligomeric silsesquioxane for vanadium redox flow battery applications

“…Figure 2a depicts the TEM image of SOPS (500 nm width) and it obviously shows the spherical‐like morphology and the particles size of 200 nm which is measured by image j analysis software using histogram plot. Figure 2b depicts a TEM image of SOPS (10 nm width) and it evidently shows the separate black spots and uniform distribution of nanoparticles 33–36 …”

“…A chemical stability test is conducted by immersing the membrane into a mixture of V 2 O 5 (0.1 mol L −1 ) and sulfuric acid (3 mol L −1 ) at 40°C for 15 days. After that, the sample weight is noted to measure the weight retention percentage 33 …”

“…After that, the sample weight is noted to measure the weight retention percentage. 33 3 | RESULTS AND DISCUSSION…”

“…Figure 2b depicts a TEM image of SOPS (10 nm width) and it evidently shows the separate black spots and uniform distribution of nanoparticles. [33][34][35][36] 3.2 | Membrane characterization…”

Sulfonated poly(ether sulfone) based sulfonated molybdenum sulfide composite membranes: proton transport properties and direct methanol fuel cell performance

“…Hence, the development of alternative PEM is important to address the above issues associated with Nafion. Recently, alternative composite membranes based on sulfonated poly(vinylidene fluoride-co-hexafluoropropylene), 12 sulfonated poly(ether ether ketone), 13,14 sulfonated polybenzimidazole, 15 sulfonated poly(ether sulfone), 16 and sulfonated polysulfone 17 have been extensively investigated as an alternative to Nafion. The above composites are formed by incorporating nanomaterials which will eventually offer high methanol crossover resistance and high proton conductivity.…”