Sulfonated poly (aryl ether sulfone) containing 1, 3, 4-oxadiazole as proton exchange membranes for medium-high temperature fuel cells

Polyoxadiazoles as proton exchange membranes for fuel cell application

The number of researches on the ion exchange membrane has increased considerably in recent years showing interest in fuel cell technology for the automobile and portable applications. The most promising fuel cell technology for low-temperature operation (80 °C < T < 150 °C) uses a polymer membrane separating the anode and cathode compartments in an electrochemical cell. Polyoxadiazoles (PODs) belong to a class of heterocyclic polymers, which possess a number of unique properties, such as thermal, mechanical, and chemical resistance. In the present review, numerous ways of POD synthesis are discussed in relation to their functional properties. In addition, different approaches to the elaboration of POD-based composite membranes are discussed in details in order to reveal the structure/properties relationship.

The preparation of novel sulfonated poly(aryl ether ketone sulfone)/TiO2 composite membranes with low methanol permeability for direct methanol fuel cells

A sulfonated poly(aryl ether ketone sulfone) (SPAEKS) with locally dense sulfonic acid groups is synthesized and different amounts of TiO2 is doped into SPAEKS matrix to prepare composite membranes (SPAEKS/TiO2-x). SEM shows that TiO2 in the composite membranes has good dispersibility when TiO2 content is not higher than 3%. The composite membranes show good mechanical properties, dimensional stability and oxidative stability. The proton conductivity of composite membranes is near to that of Nafion 117 membrane and methanol permeability of composite membranes is much lower than that of Nafion 117 membrane. Therefore, the proton selectivity of composite membranes is higher than that of Nafion 117 membrane. In particular, proton selectivity of SPAEKS/TiO2-3% (12.8 × 104 S s cm−3) is four times higher than that of Nafion 117 membrane (3.2 × 104 S s cm−3).

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.