Synthesis and properties of novel H-bonded composite membranes from sulfonated poly(phthalazinone ether)s for PEMFC

SO42-/SnO2 Solid Superacid Granular Stacked One-Dimensional Hollow Nanofiber for a Highly Conductive Proton-Exchange Membrane

A novel sulfated tin oxide solid superacid granular stacked one-dimensional (1D) hollow nanofiber (SO₄^2-/FSnO₂) is proposed as a nanofiller in sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) to manipulate a highly conductive proton nanochannel. It has unique microstructures with an open-end hollow nanofibric morphology and grain-stacked single-layer mesoporous fiber wall, which greatly enlarge the specific surface area and aspect ratio. The diverse acid sites, that is, SO₄^2-, Sn-OH Brönsted, and Sn⁴⁺ Lewis superacids, provide a high concentration of strong acidic proton carriers on the nanofiber surface and dynamically abundant hydrogen bonds for rapid proton transfer and interfacial interactions with -SO₃H groups in the SPPESK along the 1D hollow nanofiber. As a result, long-range orientated ionic clusters are observed in the SO₄^2-/FSnO₂ incorporated membrane, leading to simultaneous enhancement of proton conductivity (226.7 mS/cm at 80 °C), mechanical stability (31.4 MPa for the hydrated membrane), fuel permeation resistance, and single-cell performance (936.5 and 147.3 mW/cm² for H₂/O₂ and direct methanol fuel cells, respectively). The superior performance, as compared with that of the zero-dimensional nanoparticle-incorporated membrane, Nafion 115, and previously reported SPPESK-based membranes, suggests a great potential of elaborating superstructural 1D hollow nanofillers for highly conductive proton-exchange membranes.

Synthesis and physicochemical properties of sulfonated poly(aryl ether) PEMs containing phthalazinone and oxadiazole moieties

In this work, 2,5-bis(4-fluorophenyl)-1,3,4-oxadiazole (2F-Oz) is synthesized and successfully polymerized with 4-(4-hydroxyaryl)-phthalazin-1-one (DHPZ) through polycondensation to produce poly(ether 1,3,4-oxidiazole) containing phthalazinone units (PPEO) with intrinsic viscosity 1.54 dL g−1. A series of sulfonated poly(ether-1,3,4-oxidiazole)s (SPPEOs) with different degrees of sulfonation are prepared via postsulfonation reaction. The chemical structure of PPEO and SPPEOs was characterized through FT-IR and proton nuclear magnetic resonance, respectively. SPPEOs have excellent film-forming properties and readily dissolve in polar aprotic solvents, such as dimethyl sulfoxide, N-methyl-2-pyrrolidone (NMP), and so on. The water uptake of these SPPEO membranes with measured ion-exchange capacity of 1.13–1.61 mmol g−1 was 15.7–34.1% at 25°C and 17.9–59.8% at 60°C, and swelling ratio was 5.9–14.2% at 25°C and 6.6–18.1% at 60°C, respectively. The proton conductivity of SPPEO-1.61 is 0.045 S cm−1 at 30°C and 0.065 S cm−1 at 80°C, and the tensile strength of the SPPEO-1.61 is 48 MPa, and its elongation at break was 21%. The thermal and chemical stability of the SPPEOs is also examined.

Novel side-chain-type sulfonated diphenyl-based poly(arylene ether sulfone)s with a hydrogen-bonded network as proton exchange membranes

Diphenyl-based poly(arylene ether sulfone) membranes with a side-chain-type architecture and a hydrogen-bonded network were prepared.